Training System for Telephone Switchboard Operators Using Computer Central Processing Unit

1. Field of the Invention

The invention relates to subject matter classified in Class 35, Sub-class 8.

2. Description of Prior Art

As the result of the increased use of telephone communication facilities and services by the public, it has been necessary for the telephone industry to develop and provide call handling equipment which is capable of extending more and more calls which do not require assistance from the operator. While the provision of such equipment and corresponding rate reduction to the calling subscribers who make such types of calls has significantly increased, there are still a large number of calls, such as person-to-person calls, collect calls, credit card calls and coin distance dialing which require operator participation.

Since the complete elimination of the operator from all calls was not immediately practical, and the demands for such type service continued to increase, the telephone industry next sought to provide a more efficient arrangement for processing calls in which the operator is involved. To such end, the industry has provided so-called toll service position desks which in particular seek to minimize the participation time of the operator in making calls requiring operator assistance. In so limiting the operator participation time per call, it is apparent that each operator will be able to handle a correspondingly larger number of calls, and a more efficient system is obtained.

The toll service position desks which have been developed herebefore have, in each case, been somewhat complex. In one typical toll service position desk, the operator is required to learn the purpose and function of approximately 100 keys, and in addition the particular sequences and patterns in which different ones of the keys must be operated to process the correspondingly large number of different call types. It was quickly apparent that the training equipment previously utilized in the training of operator personnel to handle the conventional cords of a telephone switchboard were outmoded and inadequate. New types of training equipment were therefore necessarily developed for use in the training of operator personnel for the toll service position desk.

One such training unit comprises a simulator which uses a tape stored program to produce simulated training calls. The unit is equipped with a training position which has substantially the same key and lamp layout as the toll service position desk which is provided for use in the field. The training program is stored on a punched paper tape which is operative to control associated circuits to provide visual displays and audible signals at the training position to simulate different calls which the student then handles in the same manner as the operator in the field. The unit also includes a magnetic tape of the two-channel type which carries the simulated speech of customers and distant operators on one channel, and control pulses on the second channel for stepping the tape at the end of each voice message. The control pulses are also used to synchronize the two tapes at the end of each program.

In a typical training problem, the two tapes are synchronized, and the paper tape is operated to provide signals which light training position lamps. The paper tape source also sets a matching and advance circuit for the anticipated trainer response. Further codes are then transmitted to present the call condition to the trainee and the paper tape then stops. The magnetic tape may also be started by the program tape, and if so, is stopped with the program tape. If the trainee responds properly (i.e., by operating the correct key and/or providing a valid response) within a predetermined time period, the paper tape is advanced to the next training call.

While such training arrangement has facilitated the training of operator personnel in the field, the unit as manufactured has certain basic shortcomings. The use, for example, of two separate tapes for the coded voice information requires that the two tapes be in proper synchronization at all times. Obviously with the occurrence of an out of sync condition, it is necessary to have competent personnel available for the purpose of checking the system and placing the tapes back in synchronization. Of perhaps more significance is the fact that it is difficult, if not impossible, to use each training program in a given time period to provide the same to more than one training position. As a result, each training position requires a separate paper tape source and a separate magnetic tape, and even further, separate control equipment for each individual training position. Such system arrangement is of course quite costly and therefore of limited efficiency. Further since the program is stored on the paper tape, the unit has limited flexibility. That is, in the event that certain steps are to be performed in different sequences, the paper tape must be changed before such change in the mode of operation can be provided. Other shortcomings in flexibility in such type arrangement as compared with the system of the present disclosure will become apparent hereinafter.

A further training arrangement which is available in the field is disclosed in another Patent which uses a single magnetic tape for both programs and materially simplifies the operation while further avoiding the need for synchronizing the equipment, such system requires a separate program source and a separate set of controls for each training desk.

A further basic shortcoming existent in certain prior art devices lies in the inability of the units to provide simultaneous operation in the training sequences. Failing such capability the system fails to provide one of the more desirable objectives of the training system, that is, to build up operator speed in the handling of calls. By way of example, if the operator in a given response is to provide a verbal answer and simultaneously key in a response, the known systems which depend upon sequential responses will not enable the operator to practice simultaneous responses, and the training of the operator to handle the calls more quickly, cannot be achieved in such type system. In those prior art units in which an attempt has been made to provide such capability, a complex synchronization problem has resulted.

It is an object of the present invention therefore to provide a novel training system which utilizes a computer controlled central processor unit for controlling a plurality of traffic service training desks independently or simultaneously, and particularly to provide a training service desk of such type in which different, or the same functions, can be performed by the operators at each of the plurality of training units.

It is a specific object of the present invention to provide a system of such type which performs the desirable functions presently available in known systems, and additionally wherein stop or repeat can be automatically required on key pulse errors, and which includes the capability of advance or go back in training sequence upon request. The novel system also has the capability of providing printed records and accumulated statistics.

A further feature of the invention is the manner in which a simplified program permits ready change in the programming to include further lessons without hardware modification.

Yet another feature of the arrangement is the manner in which the computer compares each and every trainee response with the action which should have been accomplished and provides (a) a go-ahead (correct operation instruction), (b) a repeat instruction (incorrect operation), or (c) notifies the supervisor in the event of the occurrence of a number of errors in excess of a predetermined norm for the particular lesson being used by the trainee.

A further feature of the invention is the manner in which the computer controlled unit makes possible branching during the instruction of the trainee. That is, in many types of training it is desirable as the student progresses to a certain degree of efficiency, to request the student to bypass certain portions of the lessons and advance to a further area of training. The novel circuit arrangement of the present disclosure provides for such mode of use.

The present invention comprises a digital computer with memory having access to a tape cassette which has a plurality of different lessons stored therein. A data bus connected to the digital computer carries multiple bit address words output from the computer over a plurality of 12-bit channels to a plurality of remote operator training positions. Each of the training positions includes a toll service position training board (OTM) which is similar in format to a corresponding real world toll service position board. In addition, a control panel associated with and connected to the board is used by the trainee in selecting a desired one of the lessons for training purposes.

A lesson selection key also is operable by the trainee to start a training lesson to control word formation circuitry at the OTM to format and transmit a word to the computer which indicates the one of the OTM's which is requesting service. The computer in its routine detects the input of a "request for service" word from the calling OTM and transmits a further word over the common data bus to the OTM's which word includes the address of the particular OTM which has requested the service. Decoder means at each of the OTM's determine which OTM will accept the 12 bit word, and the decoder circuit of such OTM responsively controls the circuitry associated with the control panel to output signals to the word formatting circuit thereat to control same to generate a word which indicates the particular lesson which has been registered on the control panel equipment by the trainee.

Assuming that the requested lesson is in core, the computer then outputs a series of words over the data bus which represent the information to be displayed on the display board, each of which words includes the address of the particular OTM which has requested such lesson. The decoder means at such OTM responsively causes the identified lamps on the board to be illuminated and, (if the call and step involved so requires) causes the audio circuit at the OTM to provide audio signals to be transmitted to the headset of the trainee. The system thus provides visual and/or audio information to the trainee which is the same information as an operator in the real world will experience for the same type of call.

The trainee is now expected to respond to the audio and/or visual information by operating a certain set of keys in a given sequence as determined by the identity of the call being processed. As the trainee operates such keys, the word formatting circuitry in the OTM will form and output 12 bit words which identify to the computer the keys which were operated by the trainee. The computer compares the keys represented by the received words with the keys which are properly operated for such step. If the words compare, the lesson is advanced one step. If the words do not compare, the computer backs the lesson up one step, and retransmits the words representing the step to which the improper response was received. Additionally a record is automatically made by the computer for analysis at a later time.

The computer facility is extremely flexible and has the ability to selectively provide the information relating to a lesson and further which comprises a plurality of calls, and further to selectively provide the steps of each call in a lesson. In addition, the novel facility includes circuitry which permits "branching," i.e., as a particular trainee has advanced to a certain point, the supervisor may decide that such trainee can bypass certain of the lessons, and such bypass can be simply achieved by dialing in a new lesson number on the control panel.

The system also includes a priority tape circuit which controls the pattern and time of input to the computer of the signal output of the different OTM's, whereby each OTM is reliably serviced even though a plurality of OTM's is connected to a single CPU.

Audio circuitry coupled to the novel system provides audio signals to the trainee which are similar to those experienced in the real world. Such circuitry in addition to displaying the type of message which would normally be received from a calling subscriber or distant operator also is operative to detect audio responses made by the trainee, and if such audio response is required the training program will inhibit system operation until an audio response is provided by the operator.

The word format circuitry in the OTM's, (which is a circuit common to the control panel, the board key panel, and the individual response keys on the board) is also operative to provide multiple bit words which identify the audio responses provided by the trainee. In instances in which audio and key responses are required, the system is capable of accepting both responses simultaneously, whereby the ability to increase the operator's efficiency in handling calls is inherently provided in the system.

FIG. 1 is a block diagram of the control circuitry of the novel trainer system;

FIG. 2 is a block diagram of the toll service desk training keyboard which is used to train operators in the use of commercially available toll service desk positions of such structure;

FIG. 2A discloses the control panel which is used with such keyboard to select the different lessons (or parts of a lesson) and to provide the trainee with an indication of the results of the trainee responses;

FIG. 3 is an illustration of the word format used in the system;

FIG. 4 sets forth steps of an illustrative training lesson;

FIGS. 5-8 are detailed circuit diagrams of the OTM equipment for generating words to the computer;

FIGS. 9-12 are circuit diagrams of the decoder and storage circuits at each OTM;

FIGS. 13-14 are circuit diagrams of the audio tape control circuit; and

FIGS. 15A, B, C are diagrams of the manner in which the circuits of FIGS. 5-8, 9-12 and 13-14 are arranged.

For purposes of understanding the invention, reference is initially made to FIG. 2 which sets forth the disclosure of one commercially available type of toll service desk which is currently available from North Electric Company, Galion, Ohio, and which is described in detail in U.S. Pat. No. 3,702,381.

The general layout of the toll service desk keyboard and lamp displays are described in detail in such patent, and such disclosure is incorporated herein for reference purposes. Briefly stated, the board includes a plurality of Nixie lamps which provide digital displays of call information including charge, number, rate and time. The board further includes a plurality of illuminated keys and non-illuminated keys for use by the operator in performing varius indicated functions, and lamp indicators for visually providing information concerning the call. Reference is made to such patent for detailed explanation of the various functions which may be provided thereby. However, by way of specific example, reference is made to the steps which are performed by the operator in the establishment of a hotel 1+ paid call which requires the hotel guest to audibly provide the extension number of the hotel room to the operator, and in which the operator uses the board keyset to key such information into the system memory. More specifically, in such type of call, the subscriber initiates the call by dialing the operator digit 0. The automatic switching equipment responsively obtains and stores the subscriber directory number, and visually informs the operator by means of the lamp display that the call is a hotel 1+ station paid call with subscriber time and charge, and that a four digit room or guest number is required to complete the call.

Such information is specifically presented to the operator on the toll service position board by illuminating the calling area call lamp 18, the hotel station lamp 19, the KPGST lamp 20, the station paid lamp 21, release forward lamp 22 (red) the T and C lamp 23, the CLD lamp 24 and ACS lamp 25 in call group 1 and time ST lamp 26 (red). As the operator visually examines the board, the illuminated lamps identify the call as a hotel 1+ paid call, and the release forward lamp 22 now goes dark and zip tone will be heard on her head set.

The operator in response to such call is required to depress the KPGST key 20 and simultaneously ask the calling subscriber for the name and room number identification. At this point, the KP lamp 27 lights red and then changes to green. As the calling subscriber provides the room number and his name, the operator depresses the appropriate keys in keyset 28 to key the four digit number into the system for storage purposes. Assuming that the guest room number is identified as 0026, as the operator keys the digits into the system via keyset 28, the Nixie tube set 29 displays the digit number 0026. After a brief interval, the digit display disappears from display set 29 and the KP key 27 and KPGST key 20 go dark. The extinguishing of KP and KPGST lamps 27, 20 indicates to the operator that the equipment has obtained the necessary time and charge information, and automatically recorded such information in the toll ticketing equipment for the system. The call is now ready to be extended.

Thereupon the operator depresses the time start key 26, which changes from red to green and listens on her head set for the first ring, which is sent over the established connection to the called subscriber and to the operator headset by the automatic switching equipment. As the first ring is head the operator depresses the POS RLS (position release) key 30. At this time the lamps which were lit during the call, including the calling area code lamp 18, hotel station lamp 19, station paid lamp 21, TNC lamp 23, the called and ACS lamps 24 and 25 in loop 1 and the time start lamp 26 go dark, and the operator is ready to process another call.

The training toll service desk will, of course, have substantially the same physical layout as the toll service desk which is used in the field. Thus, if a trainer desk is to be built to train an operator to handle the toll service position desk shown in FIG. 2, the trainer desk will have the same general layout, and the signal input to the trainer desk will cause the trainer desk to provide the same visual and audio signals as are experienced in the toll service position desk and used in the field.

Assuming that the training set according to the present disclosure is to be used to train personnel for the toll service desk shown in FIG. 2, the trainer unit will include a board, such as shown in FIG. 2, and additionally will include a control panel 17, such as shown in FIG. 2A, which is used by the trainee to select the desired lesson (or part of a lesson) and to provide a display to the trainee of the correct or incorrect nature of the trainee response to the particular call condition which has been displayed on the board. For such purpose, the control panel 17 includes a three digit lesson indicator display 31 which provides a decimal readout to identify the particular lesson which is provided by the system at any given time. Different lessons may be selected by operating the digit, tens and hundreds keys 32, 34 and 36 respectively to advance the display readout to the ones of the digits which correspond to the lesson desired. Thus, assuming the hotel 1+ paid call described above is lesson 13, units key 32 is depressed until digit 3 appears in the units position, key 34 is depressed until digit 1 appears in the tens position, and key 36 is depressed until digit 0 appears in the hundreds position. The start/go switch 38 which generates an interrupt request to the computer processor unit CPU (to be described) to begin the lesson (sequence routine) first causes the CPU to examine the control panel 17 to ascertain the particular lesson which had been selected by the operator. When the CPU has ascertained the identity of the lesson selected and has selected the program for use, a signal back to control pane 17 causes the green lamp on the start/go switch 38 to light up. The CPU next conditions the training board (FIG. 2) by lighting the appropriate ones of the lamps to simulate the conditions which occur in the real world when a call of the type selected by the trainee is input to a toll service position board.

The trainee must now process the call according to the established procedure and further must process the call within a predetermined period of time alloted for the completion of such call and must complete each step of such call in the time allotted for each such step. If the training sequence is properly conducted, the system automatically provides the next step in the lesson to the trainee. However, if the trainee has made an incorrect response, the incorrect lamp 46 on control panel 17 is illuminated, and such step of the training sequence is automatically repeated. At this point, it should be noted that each lesson is comprised of a number of different calls and each call is comprised of a number of different steps. That is, when the operator sets the lesson selector 31 to 013 to select the lesson for hotel 1+ paid calls, the system will provide a series of such type calls in sequence which vary in content sufficiently to provide the operator with different information inputs for the same type of call. Each such call in a lesson is in turn divided into steps. With reference once more to the exemplary call (hotel +1 paid) the first step would begin at the time the lamps are lit on the toll service board, and is terminated with the receipt of the zip tone. The second step starts with the receipt of the reply from the customer, and the third step starts with the receipt of the ring tone from the system.

The last step or conclusion of the lesson occurs with the operation of the illuminated ones of the lamps to the dark condition.

Control panel 17 (FIG. 2A) further includes a set of keys 40, 42, 44, respectively which permit the automatic repeat of a step, a call or a lesson to thereby provide significant flexibility in the training program and pattern provided by the system. A power on-off switch 48 on control panel 17 is used to connect and disconnect power to and from the training system.

As seen from the foregoing, the control panel 17 is a quite simple and informal operation, while yet providing exceptional flexibility in its control of the training sequences.

With reference to FIG. 1, the decision making circuitry for one embodiment of the novel training system is shown to comprise a digital computer (CPU) 50, which may be of the type which is commercially available from Digital Equipment Company as a DPD-8/M unit. The CPU unit as purchased comprises a basic processor including a single address fixed word length, parallel transfer computer which uses 12 bit, two's complement arithmetic. The DPD-8/M unit further includes a core member 52 which has 8,192 word capacity and operates at a 1.4 .mu.s cycle time. Computer 50 is connected over a first set of I/O ports to an interface 56 commercially available from Digital Equipment Company as an M 1709) which provides connections to a plurality of operator training modules (OTM(1)-OTM)n) in the system in a manner to be described.

Interface 56 bascially comprises two 12-bit registers 55, 59, one of which is used as an input buffer 55 for the words provided from the OTM's and the other of which is used as an output buffer 59 for outputting words to the OTM's. The word input from the buffer 55 in interface 56 is fed over path 57 to CPU 50. Interface 56 via gate 53 signals the program interrupt terminal PI in digital computer 50 whenever the interface 56 has data to input thereat. When the computer 50 recognizes an input on terminal PI, the computer 50 interrupts its normal program operation and transfers control to an interrupt service routing in a manner to be descried. The service routine records the contents of the input buffer 55 in the core memory 52 and transfers control back to the original program.

The word output from the digital computer 50 is fed over path 58 to the second register 59 in the M1709 interface by a data transfer operation without the interrupt facility. When the program of computer 50 is ready to output data via the interface unit 56, the program loads the accumulator (not shown) in the computer 50, and issues an output command to transfer the data from the accumulator to the output buffer 59 in the interface unit 56. In order to synchronize the word output transfers, the program provides a wait period of 10 microseconds between output commands.

The digital computer 50 has access to, and is accessed by, keyboard/printer 60 which in one embodiment comprised an ASR-33 unit commercially available from Teletype Corporation, Skokie, Illinois, which includes a paper tape reader and punch which is operable at 10 characters per second. As will be shown, the keyboard/printer 60 at times may be used by attendant in the outside the world to request, via path 61, certain information relating to the process of the trainee on a printout basis. In like manner, the software in the computer 50 may be programmed to output trainee progress information over path 61 to the keyboard printer 60 at period intervals for printout process.

A digital tape cassette 62, which may be of the type commercially available from Sycor, Annarbor, Michigan, houses the computer lesson library, and is selectively connected by tape control unit 64 over a second M1709 interface 66 and path 67 to the computer 50. It is initially noted that the core member 52 has a certain section of the core set aside for temporary write in of lessons from the tape cassette 62.

As will be shown, the selection of a lesson from the lesson library stored in cassette 62 by the tape control unit 64 is effected by selective operation of the kyes 32, 34, 36 on control panel 17. With operation of such keys to select lesson 013, for example, cassette tape 62 is operated to the point on the tape which includes the selected lesson, and such lesson is transferred by tape control unit 64 over path 65 and M1709, interface 66 and path 67 to computer 50 which stores same in the temporary write in section of core memory 52. The core memory 52 in the disclosed embodiment is connected to operate with eight OTM's and accordingly will always have eight lessons stored in the core. In the event that the lesson selected by a trainee of one of the OTM's is not in core, the tape control unit 64 automatically controls the tape 62 to advance to a section of the tape which includes the requested lesson and causes the same to be placed in core along with the seven other lessons stored in core for the other seven OMT' s.

A separate time loop 68 provides timing interrupt signals over a path 69 to the digital computer 50 for the purpose of updating the internal clocks in digital computer 50.

The computer program which is more specifically described hereinafter generally comprises (a) an executive program which sequentially surveys the various equipments and upon receipt of an external interrupt relinquishes control to the interrupting routine; (b) general routines which basically actuate lamps, digital displays and examine pushkey actuation, and (c) lesson routines which generate the varying training program sequences.

Each lesson routine, as stored in core memory 52, is independently accessed by each of the OTM's as required to thereby permit each trainee to progress at the trainee's own rate. The main function of the software system in the digital computer is to control the execution of a selected set of lessons for each of the operator training units (OTM's) in the system. In general, each such lesson consists of the computer 50 executing a predetermined set of commands to the OMT's which are related to the particular lessons selected by such OMT's, and then waiting for a response from the remote as generated by the trainee. When the response arrives, the program in the computer 50 checks to see if the response is correct. If the response is correct, the program automatically advances to the next step in the selected lesson for such OTM. However, if the response is incorrect, the program lights the incorrect light 46, updates the error count with the identity of the specific OTM on which the error occurred, and automatically backs up to the previous step in the lesson.

The software system consists of the following major routines:

1. Executive Routines which control the overall flow of the system.

2. Lesson routines which contain the instructions to control the execution of each lesson. This group of instructions is unique for each lesson.

3. Common routines which contain the instructions to execute the functions which are common to all routines.

A typical control table which was utilized with the computer 50 in one commercial embodiment comprised a

1. Remote control table (RCT) which is used to store the current status of each remote in the system. There is one RCT for each OTM in the system and the first word in each RCT is pointed to the next RCT in the system, and the pointer is used to connect all of the RCTs together in a circular queue. The circular queue is used such that each remote is given equal chance to use the CPU. As the current remote relinquishes control because it is waiting for a response, the next RCT in the chain is checked to see if it is ready to use the CPU. If it is, the remote is given control. If not the next remote on the chain is checked and so on in circular fashion.

2. Output command table (OCT) which is used to store the complete set of output commands and can be transferred through the OTMs.

3. Input command table (ICT) which is used to store the complete set of input commands that can be transferred from the OTMs.

4. Lesson address table (LAT) which contains the address of the first instruction of each lesson.

5. Active remote pointer (ACT) which contains the address of the RCT that is active.

As previously indicated the computer circuitry 52 and associated tape cassette 62 has the capability of operating with a plurality of training devices OTM1-OTMn (FIG. 1). In one commercial embodiment, the system is capable of handling 32 training positions. However, the embodiment disclosed herein used only eight such positions.

Each OTM in such embodiment had the capability of interfacing with up to 128 lamps, 16 Nixie lamps and 128 pushkey switches. The OTM circuitry as shown in block from in FIG. 1 is perhaps best understood by considering the circuits in their sequence of use in a selected lesson, such as lesson 013 (a hotel +1 paid call).

To select such call, the trainee operates keys 32, 34, 36 (FIG. 2a) on control panel 17 (FIG. 2) until such digits appear on the lesson readout display 31. As the trainee then operates the start/go switch 38, signals output from control panel 17 (FIG. 1) over path 85 and OTM output circuit 124, path 70 to switch contact logic control circuit 72 results in the format of a word which is output over path 74, priority logic circuit 76 and path 78 to gate 53 on interface 56 to indicate to the digital computer 50 in word format that the digital computer 50 should pick up further information from the control panel 17 associated with OTM1.

The digital computer 50 interrupts its executive routine and via path 58 and output buffer 59 outputs a parallel word over twelve conductor bus 80 to lamp decode circuit 82 which decodes the word (sequence request) and over path 84 causes a set of gates on control panel 17 to read out the lesson selected by the keys 32, 34, 36.

Control panel 17 transmits signal information indicating the lessons selected over path 70 to switch contact logic control circuit 72 which formats a 12 bit word and outputs the same over path 70, priority logic circuit 76, and path 78 to gate 53 in the interface unit 56 which word identifies to the computer the particular lesson to be provided from OTM1. If the requested lesson is in core memory 52, the computer 50 sequentially outputs a first set of words over path 58, and interface 56 to data bus 80 and the lamp decode circuit 82 in each of the OTMs. In the present example such set of words effects lighting of the ones of the lamps on the display board which are considerably lit when a hotel 1+ station paid call is received at a toll service position board. As will be shown, such OTM has a discrete address, and accordingly, only the OTM addressed by the word (OTM1 in the present example) will respond to the word instruction.

If the lesson selected by the trainee was not in core memory 52, the computer 50 via path 67, interface 66, and path 65 identifies the number of the lesson indicated to tape control unit 64 and tape control unit 64 causes cassette 62 via path 63 to output the desired lesson back over path 65, interface 66, path 67 to computer 50 for temporary storage in core member 52.

Digressing briefly at this time, as shown in FIG. 1, clock 86 in the interface 66 outputs a clock pulse whenever a word is input to the output buffer 59 which pulse is fed over path 88 to time select clock 90 in each of the OTM's. The timer select clock circuit 90 in each OTM is operative in response to the receipt of an input clock signal to output a fifty nanosecond clocking signal over path 92 to the Nixie storage circuit 138 and lamp storage circuit 96 for the purpose of insuring that the storage circuits 96 and 138 examine the information input from the computer for only the exceedingly brief period of 50 nanoseconds. In practice, it has been found that the utilization of such momentary examination of the information significantly minimizes noise problems in the system, and makes possible a more reliable presentation of the information on the toll service board. In particular such arrangement was found to eliminate the problem of double readings which occur when longer readouts (such as for example, two microsecond readouts) were attempted.

Returning now to the description of the block diagram of FIG. 1, at this time (as shown in FIG. 4) a given set of lamps is lit to simulate the receipt of such call on the toll service trainer board. The computer 50 therefore now outputs a series of words each of which includes the address of OTM1 (the OTM which requested the call). The remaining bits of the different code words effect lighting of the lamps 18-27, which as shown in FIG. 4, include calling area code lamp 18, hotel station lamp 19, KPGST lamp 20, Sta. Paid 21, Release Fwd. 22, T & C lamps 23, Cld, ACS lamps 24, 25, and Time St. lamp 26. Such words as output by computer 50 are transmitted over path 58 to output buffer 59 in interface 59 and over data bus 80 to the lamp decode circuit 82 in each of the OTM's 1-n. The lamp decode circuit 82 in each of the OTM's is connected to data bus 80. However since the words in the present lessons have the OTM1 address only lamp decode circuit 82 in the OTM1 decodes the input words received over data bus 80 from the computer 50. Lamp decode circuit 82 provides a signal over path 98 to lamp storage circuit 96 to effect energization by lamp storage circuit 96 of the ones of the board lamps which were identified by the code words. Since each such word is applied by computer 50 to the data bus for only a 10 .mu.s period, storage circuits 96, 138 are used to store the indicated lamp operation.

As a further assist to an understanding of the operation of the system, a brief description of the word format used in the system is briefly described hereat. As shown in FIG. 3, the word format utilized in the described embodiment (i.e., only eight OTM's) comprises a 12 bit word in which the first three bits 0-2 are used as the OTM address code. In larger systems which include a larger number of training devices, the word length may be increased.

The third bit of each word in the present 12 bit word format is a dual function word. That is, if the third bit is a logic 1, an incandescent lamp is to be controlled, and if the third bit is a 0, the word indicates that a Nixie lamp in group 29 is to be controlled.

The fourth bit is also a dual function bit and the information conveyed by the fourth bit is determined by the value of the third bit. That is, if the third bit is a one (i.e., an incandescent lamp is to be lit) the fourth bit is used as an on-off bit in the word. However, if the third bit is a zero (i.e., a Nixie lamp is to be lit) the fourth bit is then used as a part of the Nixie tube address.

Assuming bit 3 is a logic 1 (an incandescent lamp is to be controlled), bits 5-11 of each word identify the address of the incandescent lamp to be controlled. Alternatively if bit three was a logic 0 (i.e., Nixie tube is to be controlled) bits 5-7 are used as the remainder of the address of the Nixie tube to be operated. In the latter event, bits 8-11 are also used as a variable Nixie BCD value.

The foregoing word format is used throughout the system in each of the circuit operations to be now described.

Continuing now with the description of the exemplary call, it is first recalled that the computer at this stage in the call has answered the OTM request for a hotel +1 paid call lesson by sending words over data bus 80 to illuminate lamps 18-26 on the board (FIG. 2) to identify the call incoming to the board as a hotel 1+ station paid call. After one second of delay time, a further word output from the digital computer 50 over data bus 80 causes the lamp decode circuit 82 in OTM1 to provide a signal over path 98 to cause the lamp storage circuit 96 to output signals over path 100 to extinguish the release forward lamp 22 (see line 2--FIG. 4).

A signal output from lamp storage circuit 96 over path 102 also causes the audio tape control unit 104 to operate tape unit 105 which responsively advances to provide zip tone over path 112 to the headset 114 of the trainee (line 3--FIG. 4). As the audio tape has progressed to the point that the recorded zip tone has been output to the trainee, an automatic stop signal on the audio tape output over path 167 is detected by audio tape control circuit 103 which outputs a signal over path 109 to interface 108 which signals the digital computer 50 to indicate that the tape at this time is in a position to stop or continue depending upon the information in the computer program. In the present example, the program will indicate that the audio tape is to be stopped, and accordingly computer 50 outputs a word over the data bus 80 to the lamp decode circuit 82, which via path 102 controls the audio tape circuit 103 to terminate advance of the audio tape by unit 103. It is noted that since only three word signals are requested from each OTM to the computer 50, a separate commercially available interface is used to provide such words to the digital computer 50. Such arrangement is also used to minimize the possibility of the occurrence of an out of sync condition for the audio tape relative to the computer program.

Continuing with the present call, as the zip tone ends, the trainee is to request the customer name and room number for keying into the system, and to simultaneously or thereafter depress the KPGST key 20 on the toll service trainer board (line 4--FIG. 4; also see key group 129 on OTM1--FIG. 1).

With the depression of the KPGST key 20 by the trainee, signals over path 122 to the OTM output circuit 124 control the word formatting circuit thereon to generate a word which identifies the key operated by the trainee and to transmit the same over path 126, input gate 128 and path 130 to gate 53 for the interface unit 56. Computer 50 in its routine picks up such word for processing purposes.

At the same time as the trainee operated the KPGST key 20 (or prior to or within a predetermined time thereafter) the trainee is required to request the guest name and room number (line 4--FIG. 4). Assuming the trainee makes such request within the allotted time period, the speech input by the trainee over microphone 87 and path 116 to the audio tape circuit 104 controls such circuit to provide a signal output over path 118 to the word formatting circuitry in the OTM output circuit 124 which responsively generates a word which indicates that a verbal response has been provided by the operator. Such word is again output over path 126, input gate 128 and path 130 to gate 55 in the interface 56 for pickup by the computer 50.

The program format in computer 50 effects a comparison of the response indicated by words input from the OTM1 with the response required by the program, and in the event the two words compare the computer outputs a word over the interface 56 and data bus 80 to the lamp decode circuit 82 in OTM1 which as decoded results in a signal over path 98 to lamp storage 96 and path 100 to effect illumination of the red portion of KP lamp 27.

A second word output by the computer one half second later in the same manner effects the illumination of the green indicator on KP lamp 27, and the extinguishment of the red portion of such lamp.

The program on computer 50 now enables the output of a word over the interface 56 and data but 80 to lamp decode circuit 82 which as decoded results in the outputting of a signal over path 102 to the audio tape circuit 103 which in turn via path 104 controls the tape unit 105 to advance and provide the guest response including the guest name and the room number (line 5--FIG. 4) over path 112 to the head set 114 of the trainee.

The audio tape circuit 103 also outputs a signal over path 109 to interface 108 which via path 110 provides a word signal to the computer 50 which indictes that the tape is in a position to be stopped or not stopped. Assuming the program instructions indicate that the tape is to be stopped, the computer 50 outputs the appropriate word for effecting such operation.

With reference to line 6--FIG. 4, it is seen that the trainee is now required to key pulse the room number (0026 in the present application) which is received from the calling subscriber into the system, and such action is effected by operating the keyset 28 (FIGS. 1, 2) in known manner. As the successive digits are keyed, the signals output over path 132 to the OTM output circuit 124 results in the generation by the word formatting circuit thereat of a discrete word for each of the digits which is input thereto. Such words as generated are output to interface 56 and computer 50 over the path previously described.

Computer 50 compares the received words with the words indicated by the program as the proper response, and in the event that the trainee has keyed the value of the word digits, the computer 50 outputs four successive words over interface 56 and data bus 80 to the OTM's which are decoded by the Nixie decode circuit 134 in OTM1. Nixie storage circuit 138 controls the operation of the four Nixie tubes in the display 29 (FIG. 2) to indicate the value of the digits dialled by the trainee (i.e., 0026 in the present example).

After a momentary delay, the computer 50 outputs further words over interface 56 and data bus 80 to the lamp decode circuit 82 to effect extinguishment of KP lamp 27 and KPGST lamp 20. Computer 50 thereafter further outputs four separate words over the same path to the Nixie decode circuit 134 to effect extinguishment of the Nixie lamps which have been illuminated.

With reference once more to FIG. 4, line 7, it will be apparent that the trainee at this time is required to depress the time start key 26 (FIG. 2) in keyset 28. With operation of key 26, a code signal over path 122 to the OTM output circuit 124 results in the generation and transmission of a word to computer 50 as described before which indicates that the time start key 26 has been depressed. Computer 50 examines the received word and compares the same with the word in program and in the event the proper key has been depressed outputs a word over interface 56 and data bus 80 to the lamp decode circuit 82 which enables lamp storage 96 to change the time start lamp 25 to green.

Immediately thereafter the computer 50 outputs a further word over interface 56 and data bus 80 which as decoded by the lamp decode circuit 82 in OTM results in a signal over path 102 to the audio tape circuit 104 for the purpose of operating the tape to output one ring over the path 112 to the headset 114 of the trainee (FIG. 4--line 8).

As the tape provides the necessary ring signal, a signal over path 107 to the audio tape circuit 103 as before results in the output of a signal over 109 to indicate to the computer that the tape unit 105 has advanced the tape to a position where a further decision is required by the program. In the present example, the program includes the tape is to be stopped, and accordingly computer 50 outputs a word back over the path described to OTM1 which responsively controls the audio tape circuit 103 to cause the audio tape unit 105 to stop the tape advance.

With reference to FIG. 4, line 9, the trainee is now required to depress the position release key 30 in keyset 129. The OTM output circuit 124 in response to the receipt of a signal over path 122 generates a word indicating that the position release key 130 has been depressed, which word is output as described above to the computer 50.

As the computer 50 receives such word, it outputs successive words over the interface 56 and data bus 80, and the lamp decode circuit 82 and lamp storage circuit 96 in OTM1 responsively effect the extinguishment of lamps 18, 19, 21, 23, 24, 25 and 26 of the lamp group 120. The system is now ready for the next lesson or call.

It is noted at this time that the computer program in addition to checking for the accuracy of the responses made by the trainee also indicates to an associated internal register the time of outputting certain keywords which require response by the trainee. At the time the required response is received, the computer checks to ascertain that such response was received within the required period. If so, the clock is reset. In the event that the trainee does not provide the response with the required period, the internal register outputs so indicate, and a word is output by the computer over data bus 80 to so indicate. The lamp decode circuit 82 and lamp storage circuit 96 in OTM1 responsively enable the incandescent lamp on control panel 17.

It will be recalled that in initiating a training operation, the trainee sets the lesson selection keys 32, 34, 36 on control panel 17 (FIGS. 1 and 2) to the number which identifies the desired lesson. In the hotel call briefly described above, the trainee set the switches 36, 34, 32 to provide digit readout 013 on the control panel 17.

With reference now to FIG. 5, the panel keys 32, 34, 36 which are so operated are shown thereat. As the trainee operates switch 32, for example, ground is connected over switch 32 to inverter 140 which puts a high level signal to a first input of AND gate 142. The second input of AND gate 142 is connected to the output of a one pulse per second generator 144, whereby pulses appear at the output of AND gate 142 for the period that key 32 is depressed. The one pps output of AND gate 142 is fed over path 147 to amplifier 146 to digit units counter 148. Units counter 148 advances as each pulse is input from generator 144, and at its outputs 150, 152 and 154 provides a binary coded signal indicating the value of the accumulated count to a seven segment driver 156, which is commercially available from Texas Instruments as a 7446 unit. The decimal output of the seven segment driver 156 is connected over conductor 149 to a seven segment LED display which provides a display of the units digit (3) on the units display U of lesson indicator 31 on control panel 17. That is, as shown in FIGS. 2A and 3, lesson indicator 31 is comprised of three LED display units, which are commercially available from Schelly as No. 3015F-CN one of which, U, is connected to display the selected units digit, the second of which, T, is connected to display the selected tens digit, and the third of which, H1, is connected to display the selected hundreds digit.

The trainee having advanced the units count to digit 3, now operates the tens switch 34 to provide a low level signal to inverter 160 which in turn provides a high level to one input of AND gate 162 to cause one pulse per second to be gated from generator 144 to one input on OR gate 164 and over amplifier 166 to the tens counter 168. In the present example, the trainee holds switch 34 closed until counter 168 advances to count 1.

The binary output of counter 168 is fed to LED seven segment driver 180 which provides a digital output over conductors 169 to the second seven segment LED display T to effect the display of the digit 1 thereon for the operator. The trainee operates the hundreds switch 36 in like manner to provide a hundreds digit "0" on the lesson indicator 31. As switch 36 is closed a high level pulse output from inverter 170 causes AND gate 172 to gate one pulse per second over OR gate 174 to hundreds counter 178. It is noted that counter 178 is wired to provide a maximum count of three in the present embodiment. The binary count output of counter 178 is fed to seven segment driver 182 and the decimal output of driver circuit 182 is fed to the seven segment LED display H in the lesson indicator 31. The display to the operator on control panel 17 at this time (FIG. 2) will therefore read 013, which is the number assigned to the lesson involving the hotel 1+ call.

Digressing briefly, it will be apparent that the highest order output of counter 148 is connected via differentiator circuit 184 to a second input on OR gate 164 and over amplifier 166 to the input of tens counter 168. In like manner, the highest order output of tens counter 168 is fed over differentiating circuit 186 to the second input on OR gate 174 and over amplifier 176 to the input of hundreds counter 178. Thus if the trainee prefers, the units switch 32 can be held down to effect advancement of the lesson number to any desired value requiring the selective operation of switches 34 and 36. The lesson count 013 placed on the three counters 148, 168 and 178 is held in the counters until the trainee once more operates the switches 32, 34, 36 to select a different lesson. Such count is marked over three separate paths 115, 165, 175 to a group of lesson counter readout gates 341-348, which as will be later described, are used to form words for gating to the computer 50 to indicate the particular lesson selected by the trainee.

The trainee having selected a lesson 013 on control panel 17 now operates the start/go switch 38 to cause the system to start the lesson. With reference to FIGS. 5 and 6, switch 38 as closed applies ground over path 190, and is fed as an input to word format circuit 191 for OTM1 which comprises seven bit generating gates 192-198 for providing bits 5-11 respectively of each word output by the operator trainer module OTM-1 to the computer 50. In the present example (as shown in the code table hereinafter) the Start word (in code) is 1000111, and accordingly the path 190 is connected to control the gates for bits 5, 9, 10, 11 respectively (192, 196, 197, 198) to generate a logic 1 for such word. Gates 193, 194, 195 being unconnected will output logic 0 when the bits for the Start word are readout.

With logic 1 output from bit gates 5, 9, 10, 11, the corresponding AND gates of the group 206A-206G connected to the outputs of gates 192-198 respectively output a low level signal (absent an inhibit signal over inhibit lead 210) and the AND gates of group 206A-206G connected to the output of bit gates 6, 7, 8 will output a high level signal. As seen in FIG. 6, the outputs of AND gates 206A-206G are connected over path 70 to the switch contact logic control circuit 72 (FIG. 7) and the input of an OR gate 208 to initiate a word readout cycle.

More specifically, with the energization of any one of the bit gates 192-198 by a low level signal, a corresponding one of the outputs of gates 206A-206G over path 70 will be marked to indicate to gate 208 in the key channel 207 that a word must be generated for the computer (CPU) 50. The signal output from OR gate 208 is fed over amplifier 210, and differentiated by differentiator circuit 212, amplified by circuit 214 and fed to one input of AND gate 216.

The output of AND gate 216 is fed to 10 millisecond multivibrator 218 which outputs a 10 microsecond negative going pulse to the input of a 50 millisecond multivibrator 220 which, in turn, at its output provides a signal to the second input of AND gate 216 to inhibit any further pulse input over the key channel 207. The positive-going pulse output from the multivibrator 218 is fed to a further 10 millisecond multivibrator 222, which generates and transmits a 10 microsecond output pulse over inverting amplifier 224 to one input of OR gate 226. The output of OR gate 226, in effect, comprises a clocking pulse which is used to clock the data bits which are output from the bit gates 192-198 (FIG. 6) to input gate circuit 128.

More specifically, the word information (Start word in the present example) which is marked on the inputs of bit gates 192-198 and gated over gates 206A-206G to each of the corresponding OR gates 228A-228G are fed to the J inputs of flip-flops 230A-230G respectively.

Recalling that the input of the word to the bit gates 192-198 also resulted in a signal over path 70 to key channel 207 (FIG. 7) which in turn resulted in a 10 .mu. second clock pulse over path 227 to the clock input of flip-flops 230A-230G, it will be apparent that the bit markings on the J inputs of the flip-flops 230A-230G which represent the code for the Start signal (1000111) are output by the flip-flops over paths 230A-230G as a parallel word readout on conductors 236A-236G to the input gate circuit 128 (FIG. 8).

With reference once more to FIG. 7, and the output of key channel circuit 207, it will be seen that the clock pulse output therefrom is also fed over a first and a second series connected amplifier 238 and 240 for the purpose of effecting a slight delay in the generation of the clock pulse signal which is fed to the clock input of a JK flip-flop 242. The Q output of the JK flip-flop 242 is fed over amplifier 244 to mark output lead OTM1 in the priority logic circuit 76, (FIG. 8) and thereby provides a signal request for a computer interrupt at the appropriate time and the pickup of such word by the computer.

The priority logic circuit 76 basically comprises a 100 microsecond oscillator 246 which provides output pulses over amplifier 248 and AND gate 250 to the input of an eight-bit ring counter 252. As will be apparent from FIG. 8, the gate outputs of ring counter 252 are connected to gating circuits for the OTM1-OTM8 request leads output from the different OTM training module OTM1-OTMn (n=8 in the disclosed embodiment). Thus, as shown, the lowest significant bit output of ring counter 252 is fed over an amplifier 254 as one input to AND gate 256A. The second input of AND gate 256 comprises the request lead output OTM1. It will be apparent that as the ring counter advances over the successive output leads, the request leads of the successive OTM training units are connected over path 77 to input gate 128. The outputs of gates 256A-256G are thus successively connected to the one microsecond multivibrators 258A-258G respectively. As such scan occurs, those OTM's (such as OTM1 in the present example) which have a mark on the request lead, obtain a 1 millisecond pulse on the output leads, such as RR1, in path 77. The request signals which appear on conductors RR1-RR8 in sequence (if any) in each scan are fed successively to the RR1-RR8 inputs of 56 gate circuits, such as the eight gates 260A-260G (FIG. 8) for bit 5 in the input gate circuit 128. As will be shown, the number of gate circuits, such as 260A, is determined by the number of bits in each word and the number of OTM's in the system.

With specific reference to input gate circuit 128, it will be apparent that there is a set of eight gates for each of the bits 5-11 (i.e., a total of 56 gates). The first gate for each bit, such as gate 260A for bit 5, has one input connected to the bit 5 output of training position OTM1, and each of the successive gates 260B-260G has one input connected to the bit 5 output of training positions OTM2-OTM8. In like manner, the first gate of each of the eight gates for bit 6 has one input connected to the bit 6 output of OTM1 and the successive seven gates for bit 7 have one input connected to the bit 7 output of OTM2-OTM8 respectively.

The second input of each of the gates, such as 260A-260G for bit 5 of OTM1-OTM8, are connected respectively to the RR1-RR8 outputs of the priority logic circuit 76. The second input of each of the eight gates of bits 6-11 are connected in like manner. It will be seen therefore that if the RR1 conductor output from priority logic circuit 76 is marked (and such conductor as described earlier is marked only if there is a word in OTM1 to be input to the computer 50), the first gate, such as gate 260A, for each of the bits 5-11 will be enabled to extend said bits over OR gates 262A-262G as the signal is input over conductor RR1. As the ring counter 252 advances one step (and assuming that the OTM2 also has a word to be input to the computer), the RR2 signal will cause the 7 bits of the word output from OTM2 to be applied to gates 262A-262G. Thus in each scan ring counter 252 will cause the word output of the OTM's which have requested service to be output successively over gates 262A-262G.

The OTM words as output over the OR circuits 262A-262G, are extended over individual inverter amplifiers 264A-264G and over path 130 to input buffer circuit 55 (FIG. 1) in interface 55 for input to the computer 50 as the computer proceeds to such point in its routine.

With reference once more to priority logic circuit 76, (FIG. 8), it will be seen that the signal output from each of the request circuits RR1-RR8 are also connected as inputs to an OR gate 270 which is connected over path 78 (FIG. 1) to gate 53 which has its output connected over path 51 to the priority interrupt (P1) for the computer 50. This it is apparent that as the bit ring counter 252 advances in its scan to provide a request signal over a conductor, such as RR1, the same signal is also fed over a path such as 259 to gate 270 and path 78 to the interface to mark the priority interrupt terminal (P1) of computer 50 with a program interrupt signal.

The signal output from OR gate 270 is also fed over path 272 to inverter amplifier 274 and a second input on AND gate 250 to inhibit the output of the oscillator 246 to the ring counter 252, and thereby terminate advance of the ring counter 252 until such time as the request signal, such as RR1, is removed from the particular request lead which has causes the program interrupt terminal P1 to be marked on the computer 50. As noted above, the request signal from an OTM position, such as the signal on lead OTM1 (FIGS. 7, 8) is a 1 ms. signal.

Briefly summarized, the signal generated for the purpose of determining computer service for an OTM in addition to marking the computer program interrupt terminal P1 over path 78, also inhibits further advance of the ring counter 252 via lead 272 to provide a one millisecond interval in which computer 50 may determine the nature of the request and process the same.

Whenever the ring counter 252 (FIG. 8) generates a signal over an RR lead, such as RR1, for use in the priority gating of a word over gate circuit 128 to the computer, the same signal over the RR lead, such as RR1, is also fed over reset conductor 259 (FIGS. 7, 8) to the reset input of the flip-flop 242 (FIG. 8). The same signal over differentiating circuit 582, inverting amplifier 584 and conductor 586 provides a reset signal to the flip-flops 230A-230G (FIG. 6) which were enabled to gate the word from the bit gates 192-198 to the input gate circuit 128. Thus, if computer 50 has not picked up the information during the 1 ms. period, the information will no longer be available during such cycle.

As the interrupt service signal output by the priority logic circuit 76 over conductor 76 is applied by gate 53 to the computer terminal P1, computer 50, as shown in the program description hereinafter, interrupts its routine, and examines the Start signal input from OTM1 over path 130 (FIG. 8, 1) and buffer 55.

As the digital computer 50 determines that the signal from OTM1 is a start word, the program in the computer 50 outputs the sequence counter code word (000111100001) over path 58 (FIG. 1) to output buffer 59 (which is a 12 bit register used for buffering purposes). Buffer 59 is connected over data bus 80 which comprises twelve parallel leads, which are connected to the inputs of the lamp decoder circuit 82, Nixie decode circuit 134, and timer select clock circuit 90 in each of the training modules OTM1-OTMn in the system. In addition, the clock output of a separate clock 86 is fed over clock conductor path 88 to the timer select clock 90 for purposes to be described. Digressing briefly, it is noted that logic 1 in the words output from the computer are low level signals. With reference to FIG. 9, the manner of connection of data bus 80 to an OTM (such as OTM1, for example) is shown to comprise twelve parallel input paths (bit 0-bit 11) and a thirteenth input path which is connected to the clock path 88. The bit input paths 0-11 are each connected over a separate amplifier, such as 280A-280L, to the decoder circuitry for the OTM. As was indicated earlier, the first three bits of each word provide the OTM address code (three bits are used in the present embodiment which has a total of eight OTM devices). In the binary code, the first OTM1 is identified by bits 000, and accordingly such markings on the first three conductors of the data bus 80 result in high level signals output over amplifiers 280A-280C to OTM selector circuit 281, which as input to AND gate 282 along with the clock pulse fed over amplifier 284 and differentiating circuit 286, results in a low level output signal to amplifier 290, which in turn outputs a high level signal to one input of each of the lamp selection gates 292 and 294.

Digressing briefly, it is noted that the particular connections shown for the OTM selection circuit 281 in FIG. 9 are such that AND gate 282 will output a signal only if the three bits input over bit conductors 0, 1, 2 of data path are low (if any one of the three bits is high, AND gate 282 will not output a marking signal.) It should be understood that the OTM selection circuit 281 in each of the other OTM selection circuits (for units OTM2-OTMN) will each be connected in a different configuration. Thus, the address code in the word address to OTM2 would be 100, and accordingly the output circuit of amplifier 280 would be extended over an inverter in the selection circuit for OTM2 to the second input of its AND gate 282, and all of the inputs for the AND gate 282 in OTM2 would appear high only when the code input on bit inputs 0-2 are 100. The manner in which the other six OTM selection devices are implemented to provide such manner of response only when its particular code is included in the code will be apparent therefrom. Summarized, the first three bits of a word in data bus 80 comprise a discrete address for only one of the OTM's, and the selector circuit 281 at each OTM is implemented to output a circuit only when its assigned address appears as bits 0-2 of the word of data bus 80.

As an OTM selection circuit 281 (FIG. 9) provides an output signal over conductor 282A as the result of detection of its address in a word on data bus 80, the lamp selection gates, such as 294, 292 in only the OTM addressed by the first three bits will be prepared for operation. In the present example, lamp select gates 292, 294 in OTM1 have been so prepared by the marking of one input thereto.

The particular one of the lamp select gates 292 and 294 which is enabled in the OTM1 is determined by the value of bit 3 in the word on data bus 80. That is, as indicated earlier, and shown in FIG. 3, if bit 3 is a logic 1, an incandescent lamp is to be controlled, and if the bit 3 is a logic 0, a Nixie lamp is to be controlled.

In the present example (sequence counter word 000111100001) bit 3 is a logic 1, and accordingly the output signal of amplifier 280D over path 304 to the second input on gate 292 will be a high level signal, and the signal output of amplifier 280D as fed over inverter 306 is a low signal over path 308 to the second input on gate 294. As a result, only AND gate 292 will be enabled, and gate 294 will be inhibited. The output of AND gate 292 therefore at its output marks the Select Clock Lamp conductor 302 which provides a marking signal for one input of AND gate 310 in lamp storage circuit 96 (FIG. 11). With Nixie select gate 294 (FIG. 10) inhibited the Nixie storage circuits (FIG. 12) will not be prepared for operation.

It will be recalled that bit 4 in each word on data bus 80 is used as an on/off bit whenever an incandescent lamp is to be controlled (i.e., whenever bit 3 is a logic 1). In the present example, bit 4 is a 1, and as a result a high level output is fed by amplifier 280E (FIG. 9) over path 312 (FIGS. 9, 10, 11) to the D input of the eight bit decoder-latch circuit 313, which circuit is commercially available from Fairchild as D9334. When the input of decode-latch circuit 313 is marked by a low level signal, and input D is marked by a high level signal, the decode-latch circuit 313 will provide a decimal output over conductors 4-12 which is determined by the value of the binary markings on the inputs A-C.

It will be recalled that in words in which the control of an incandescent lamp is indicated (bit 3=logic 1) bits 5-11 are used for address purposes. In the present word, bits 5-8 are 1100 and the inputs to amplifiers 280F-280I (FIG. 9) will be low, low, high, high respectively (i.e., logic 1 signals from computer 50 are low).

The outputs of the amplifiers 280F-280I are fed over conductors 283-285 to the inputs for Nixie Decode Circuits 134 and over conductors 286-289 as inputs to Lamp Decode Circuit 82 as high, high, low, low signals respectively. The Nixie Decode Circuit 134 and the Lamp Decode Circuit 82 are decoders available commercially from Texas Instruments as 74154 devices. In effect, decoders 134, 82 provide binary to hexa-decimal decoding at the output, whereby only one of sixteen output conductors is marked to indicate the value of the signals marked on the four input conductors (bits 5-8). While both decoder circuits 134 and 82 are operated, since bit 3 was a zero in the exemplary word, the circuit is interested only in the output of the Lamp Decode Circuit 82.

The four signals (low, low, high, high respectively) input to Lamp Decode Circuit 82 as a result of word bits 5-8 (1100) will output a low level signal to amplifier 322M and a high level signal over conductor FDC to one input of gate 310. Since the first input of amplifier 310 was marked with a high level signal by reason of bit 3 being a logic 1, gate 310 provides a low level enabling signal to input E of the eight bit decode-latch circuit 313. The decode-latch circuit 313 responsively decodes the bit inputs on bit conductors 9, 10 and 11 (FIG. 9) which have been inverted by amplifier inverters 280I-280L, and fed over contacts 317, 319, 321 (FIGS. 9, 10) to the ABC inputs of decode circuit 313 (FIG. 11). Bits 9-11 of the exemplary word on 001 and the inputs to the ABC terminals are therefore low, low, high respectively. With such input to terminals ABC, the decode-latch circuit 313 outputs a high level signal on conductor 1, which as applied over amplifier 326B, 328B to the base element of transistor 330B, results in a high level signal on output conductor C1 which is connected as a control conductor 332 for the read sequence counter (FIG. 7).

With a high level input signal over conductor 332 to AND gate 334 (FIG. 7), a low level signal is output over conductor 336, and amplifier inverter outputs a high level signal over conductor 340 to mark one input to each of the lesson counter readout gates 341-348 with a high level signal (FIG. 5). In the present example, it will be recalled that the trainee via switches 32, 34, 36 on control panel 17 selected lesson 013. As a result counter 178 marks the second input of gates 341, 342 with logic 0, counter 168 marks the second inputs of gates 343-345 with 001 respectively, and counter 148 marks the second input of gates 346-348 with 011 respectively. The bit output from lesson counter readout gate 341-348 is therefore 00001011 which is the code word of lesson 013.

The outputs of the lesson counter readout gates 341-348 are connected over path 85 to the second input on OR gates 228A-228G (FIG. 6) which were utilized in the previous example to provide thw word for interrupt service to the computer 50.

At this time, reference is once more made to the signal input on the read sequence counter (conductor 332--FIG. 7), and the resultant signal over AND gate 334 and conductor 336 to the 10 millisecond multivibrator 350, the output of which is connected to a 10 microsecond multivibrator 352 and also over path 354 to an inhibit switch conductor which is connected to the second inputs of AND gates 206A-206G (FIG. 6) to prevent the inputting of information from the trainee keys during the period that the read sequence counter is outputting information to the computer 50.

The output of the ten microsecond multivibrator 352 is fed over path 356 to a second input of gate 226 to provide a clock signal over path 227, in the manner heretofore described, to the flip-flop circuit 230A-G in the OTM1, whereby the word representing the selected lesson as input to the flip-flops 230A-230G by the OR gates 228A-228G is clocked via input gate circuit 128 and path 130 to the gate 55 for pickup by the computer 50.

As the computer 50 detects that the word input from the sequence counter word indicates that lesson 013 has been selected, the computer 50 outputs a word which terminates the readout of the sequence counter in the OTM1. Such word is identical to the read word previously transmitted with the exception that bit 4 is now a logic zero rather than bit 1 (i.e., the logic 0 terminates the operation to prevent switching by logic bit 1). The OTM1 circuitry responds to such word in the manner previously described, and bit 4 as inverted by amplifier inverter 280E is fed over conductor 312 (FIGS. 9 and 10) to the decoder 313 (FIG. 11) to disable decoder 313 and terminate the signals previously output therefrom over read sequence counter conductor 332 (FIG. 7) to terminate readout of the lesson word.

The program in the computer 50 now controls the output of successive words over data bus 80 which includes the address for OTM1 and the code respectively for the calling area code lamp 18, the hotel station lamp 19, the KPGS lamp 20, the station paid lamp 21, the release forward lamp 22, T and C lamp 23, called lamp 24 and ACS lamp 25 in loop 1, and time start lamp 26. As the different words are successively applied to the data bus, lamp decode circuit 82 (FIG. 10) in OTM1 operates in the manner previously described to cause control lamp storage 96 to provide enabling signals over the appropriate ones of the lamp control conductors (not specifically shown, but similar to control conductors CO-C7, etc), for the identified ones of the lamps.

Table II which appears hereinafter indicates the codes which were transmitted over the system in one embodiment and which resulted in the enablement of those lamps which are identified on such table.

One-half second later the program in pulse computer 50 transmits the code word which is detected by lamp decode circuit 82, and causes lamp storage circuit 96 to extinguish the release forward lamp. Step 1 of lesson 013 (see FIG. 4) is now complete.

The next step in the call (FIG. 4, line 3) requires the provision of a zip tone to the operator headset. The computer program 50 now therefore sends out code word 000111100101 which is a Start Audio code. The Start Audio word as applied over the data bus 80 in the manner of the previous words is detected by the lamp decode circuit 82 at OTM1 only, and the lamp storage circuit 96 (FIG. 11) is enabled to mark the Start Audio conductor 340 in the same manner that read sequence counter 332 was enabled.

The Start Audio marking signal applied over conductor 340 is fed to the audio tape control circuit 103 (FIG. 14) and over OR gate 342 and over amplifier 344 to OR gate 346 and an amplifier transistor 348. The resultant control signal output in the collector circuit of transistor circuit 348 enables the drive unit of the audio tape cassette unit which in one embodiment comprised a tape cassette, which is commercially available from Panasonic as a 272S.

The start audio signal output from OR gate 342 is also applied to the two second multivibrator 350 and one input to AND gate 352 which is inhibited by the signal on its second input at this time.

The audio cassette unit 105 operates, and as the cassette tape in the unit which carries the audio cues for the lesson (Hotel 1+ Call Station Paid) advances, a 270 hertz signal recorded on one of the tape channels is applied to the write channel of the audio tape head and fed over path 112 to the head set 114 of the operator.

The 270 herts signal on the write channel is also fed over path 107 to high tone and low tone filters 354 and 356 (FIG. 13) in the audio tape control circuit. Low tone filter 356 is designed to pass 270 hertz signals, and the signal output from filter 356 is applied over conductor 360 to one input of amplifier 362. The amplified signal output of amplifier 362 after rectification by rectifier 364 is further amplified over a transistor 366 and fed to the latch reset flip-flop 368. Such circuit is commercially available as a 7400 from Fairchild.

As the latch reset 368 operates, a signal output over step tone conductor 370 and inverter 371 (FIG. 14) is fed to one input on step tone gate 372, and to one input on lesson tone gate 374. Since the repeat lesson and repeat calls signals are not present on conductors 485, 486 at this time, AND gate 372 outputs a low level signal which is fed over amplifier 378 as a high level signal to one input of AND gate 380.

At this time, the second input of the gate 380, which is connected over conductor 382 to the tone reset lead (FIG. 7) also has a high level signal, and accordingly gate 380 outputs a signal over power inverter 386 to provide a signal over the Stop on Step Tone conductor path 109 to interface 108 which provides a hardwired code word output to the computer over path 110 to indicate that zip has been transmitted. As digital computer 50 detects such word, bit 4 in the Start Audio word is changed from a 1 to a 0.

The Start Audio word, as thus modified, is transmitted over data bus 80 in the manner of previous words, and lamp decode circuit 82 and lamp storage circuit 96 (FIG. 11) in response to the Start word with bit 4 a logic 0 causes the Start Audio signal to be removed from conductor 340 and the enabling circuit for the audio control circuit in turn removes the "run" signal from conductor 349 to stop the tape advance.

As was noted above, the audio tone output by the tape unit 105 was applied to the headset 114 of the trainee. In the real world when the operator receives the zip tone and the board is illuminated as shown in FIG. 4, line 1, the operator will simultaneously, or sequentially, request the name and room number of the calling subscriber and key such information into the system (FIG. 4--line 4).

Digressing briefly, each of the TSD keys, such as KPG57 key 27, on the trainee board (FIGS. 2 and 6) as operated, completes a discrete circuit which enables the word format circuitry 191 (FIG. 6) to generate its own preassigned code word for transfer to the computer 50. Code table II represents the codes provided by the TSD keys, only a few of which are specifically shown in FIG. 6.

In implementing such table each key, such as KP GST 27, has its operating circuit connected to those bit gates in the word format circuit 191 (FIG. 6) which are to generate a logic 1. Thus in the case of the KP GST key 27, the key 27 and conductor 392 are connected to the fifth and the tenth bit gates 192 and 197 respectively. The other board keys are connected in like manner to provide the codes shown in Table II hereinafter.

Returning now to the call, as the trainee presses the KPGST key 27 (FIG. 6), a ground signal over conductor 392 to bit gates 192 and 197 (the gates for bits 5 and 10) enables only gates 192 and 197 to output a logic 1. The other gates 193, 194, 195, 196 and 198 not being so marked will output logic 0, whereby the KP GST code 1000010 is output by the bit gates 192-204. With such marking of the bit gates 192-198, the signals over gates 206A-206G and path 70 to the switch contact logic control circuit 72 (FIG. 7) will enable the key channel 207, as before described, to generate a clock output over path 277 to the clock inputs on the flip-flops 230A-230G (FIG. 6) to effect parallel gating of the KPGST coded word 1000010 over input gate circuit 128 and path 130 to the computer interface as the priority logic circuit 76 reaches such OTM in its scan.

It will be recalled that the same pulse output from the key channel 207 provided a signal over the RR1 lead to identify the OTM1 unit as the unit which is requesting computer service. That is, the RR1-RR8 signals are applied to the input gate circuits 128 (FIG. 8) in a given sequence, whereby the word output of the OTM circuit 124 is always gated to the computer at a given position in the sequence of words which is fed over path 130 to the gate 55 in interface 56 for detection by the digital computer 50 in its routine as the computer detects an interrupt request.

The computer program in the present call recognizes the need for a voice check, and accordingly outputs the word 000111100111 over interface 56 and data bus 80 (FIG. 1). The lamp decode circuit 82 (FIG. 9 and 10) operates to provide a signal to the lamp storage circuit 96 (FIG. 11) which in turn provides a voice check signal over conductor 398 in path 102 to the audio tape control circuit 103 (FIG. 13) and to one input on AND gate 400. The second input to AND gate 400 comprises a No Keys signal which is input from key channel 207 (FIG. 7) via conductor 401. Gate 400 will thus be enabled whenever there are no TSD keys operated, and a computer has forwarded a word requesting a voice check. Gate 400 responsively outputs a low level signal to inverter amplifier 402 to one input of audio detect gate 404. The second input of AND gate 404 awaits the signal which indicates that the trainee has responded with a voice answer.

Assuming the trainee now makes the desired response, i.e., "Your name and room number please," (see FIG. 4--line 4) into the microphone 87 (FIGS. 1, 13) the voice signals of the trainee are fed over conductor path 116 to a low pass filter 406 in audio tape control circuit 103. The voice signals output by filter 406 are rectified by rectifier 408 and fed to a transistor amplifier 410 which provides a signal over "voice present" conductor 412 and inverter amplifier 414 to the second input of the audio detect gate 404.

With the conditions described above (Voice check signal received from the computer on one input and No Keys operated on the TST board), and the detection of the voice as spoken by the trainee, an audio detect gate 404 will output a low level signal to the multivibrator 416 to cause same to provide a 30 millisecond spike over Sound Present conductor 118 to input 45 for the word format circuit 191 (FIG. 6) which is connected to the bit gates 192, 195, 196, 197 (bits 5, 8, 9 and 10) respectively. As in the previous word formatting cases, the marking of the code word Sound Present 1001110 on the bit gates 192-198 enable the OTM output circuit 124 (FIG. 6) to output the Sound Present signal over input gate circuit 128 (FIG. 8) and path 130 to the interface 56 (FIG. 1) and computer 50.

When the computer 50 receives both the indication that the word which indicates the KPGST key 27 has been depressed, and that the operator has given a voice response, the computer program outputs a Stop Audio word in the manner described above (code 000111100101), which is fed over interface 56 and data bus 80. Lamp decode circuit 82 and lamp storage circuit 96 in OTM1 (FIGS. 9-11) responsively output a signal over Start Audio path 340 (FIG. 11) to the audio tape control circuit 103 (FIG. 14) and over OR gate 342, inverter amplifier 344, OR gate 346, and amplifier 348 to the Run conductor in path 104 to start advance of the audio tape cassette 105. As the cassette advances, voice signals recorded on one tape channel is output over path 112 to the head set of the trainee ("26, please" in the present call as shown in FIG. 4--line 5) and the 270 Hz signals recorded on the second channel are output over path 107 to the filters 354, 356 in the audio tape control circuit 103 (FIG. 13). The 270 Hz input signal from the tape over filter 356 results in the enablement of such circuit, as described heretofore, and results in the generation of a step tone signal output overconductor 370 to inverter amplifier 371 and Step Tone gate 372, amplifier 378, AND gate 380 and inverter amplifier 386, which signal operates as a Stop On Step Tone 420 over path 109 to the interface 108 which responsively outputs a corresponding word (hardwired on the interface) to the computer 50. With the receipt of such word, computer 50 changes the fourth bit of the Start Audio word from a logic 1 to logic 0. With the outputting of such word by the computer over the data bus 80, the lamp decode circuit 82 and lamp storage circuit 96 (FIGS. 9-11) remove the signal from Start Audio conductor 342, and the audio control tape circuit 103 (FIGS. 13, 14) responsively removes the enabling signal from the Run lead to the audio tape cassette 105, whereby the tape cassette stops.

At this time, the trainee is expected to key pulse the room number 26 into the system. In that the particular system used in the field requires the input of a four digit number for each room number, the trainee now uses the key pad 28 (FIGS. 1,2,6) to key pulse the digit 0026 into the system. With reference to FIG. 6 the key pad 28 is seen to comprise seven switches which are operated in various combinations by the ten keys 28 on the board. More specifically, the contacts A-G associated with the ten keys are operated in various combinations to provide signal outputs over conductors according to the path shown in the key code table below.

By way of brief explanation of key pad 28, as the operator depresses key zero to enter the first digit of the guest room number, the A key closes to provide a ground signal over conductor 422 to decoder 436. The decoder 436 comprises a series of AND gates connected in the manner indicated by the truth table above to provide a signal output over Key Zero lead 456 which has been assigned the code 0001010 and which is therefore connected to bit gates 195 and 197 (FIG. 6). As the bit gates 192-198 are thus loaded, the OTM output circuit 124 and input gate circuit 128 operate in the manner previously described to output the Key Zero word (0001010) over path 130 to gate 55 on interface 56 for pickup by the digital computer 50.

With reference to FIG. 4, line 6, it will be seen that the Nixie lamps 29 (FIG. 2) will momentarily display the digits which are being keyed by the trainee for the purpose of reporting the room number of the guest (0026 in the present example). As the computer 50 receives the word from the OTM1 module indicating that the trainee has keyed the first digit 0, computer 50 outputs the word 000001100000. As earlier described, the first three digits are the OTM address code (000 representing the OTM1 in the system) and when the third bit is a zero the bit indicates that a Nixie lamp is to be selected. In addition, when the third bit is 0, the bits 4-7 are used as the address of the "bin" or the particular Nixie of the set which is to be selected (in this case, the first Nixie tube in the group 29--FIG. 2), and bits 8-11 are used to indicate the value to be displayed by the selected one of the Nixie tubes.

In the present example, the word output by computer 50 over data bus 80 indicates that the first Nixie tube of the four tubes 29 is to be controlled to display a 0 digit. As will be shown, the Nixie decode circuit 134 in OTM1 operates to provide an output signal which effects display of the 0 digit on the first Nixie tube.

More specifically, with reference to FIG. 9, the first three bits 000 of the word are input over amplifiers 280A-280C and decoded by the OTM selection circuit 281. Since the first three bits are 000, the OTM selection circuit 281 for only the OTM1 circuit will enable its associated selection gate 282 to prepare the Lamp and Nixie selection gates 292, 294 for operation. Since the fourth bit is a zero (i.e., bit 3 of the word) the low level signal input over amplifier 280D, inverter 306 and conductor 308 will result in the enablement of selection gate 294 which outputs a signal over inverter amplifier 296 and Select Nixie path 298 to the select gates 460A-460G for each of the Nixie Selection Circuits 468A-468O to prepare the same for enablement.

With reference once more to the word which is input over data bus 80 (FIG. 9) it will be recalled that the bits 4-7 identify the particular Nixie tube on the board which is to be selected for illumination (in this case Nixie Tube 7 of group 29), and accordingly the bits 4-7 of the input word are 0110 respectively. Such signals are input over inverter amplifiers 280E-280H to the Nixie Decode Circuit 134, which is a 4 to 16 decoder of the type commercially available from Texas Instruments as 74154, and the input signals 0110 result ina signal output over amplifier 320G and path 464G to a second input for select gate 460G. The select AND gate 460G for the seventh Nixie tube now gates a low level signal over amplifier 462G to the storage circuit 468G for Nixie tube 7.

The storage circuit 468G, as shown, comprises a quad latch which includes four flip-flops, which may be of the type commercially available from Texas Instruments as 7475 devices, each of which is connected to store a different one of the bits input over bit 8- bit 11 conductors respectively. Briefly summarized, each Nixie tube has a similar storage circuit, but only the storage circuit associated with the particular Nixie tube identified by bits 4-7 will be enbled for the purpose of decoding the particular digit which is identified by the bits 8-11 in the word input over data bus 80.

In the present example in which Nixie tube 7 is to display the digit 0, the inputs over bit conductors 8, 9, 10 and 11 will be zeros respectively, and accordingly the Q outputs of the four latch circuits 470-474 will be 0, and the Nixie driver and decoder circuit 476G (commercially available as a 7441 unit) for the storage circuit 468G outputs a signal on the Nixie "zero" conductor for the first Nixie tube of the set 29 to enable the same to display a 0.

In like manner, as the trainee depresses the key "zero" on the key pad 28 (FIGS. 2, 6) a second time, the same Key Zero code word 0001010 is provided by the circuitry to the computer 50, and the computer responsively outputs the word 000001110000 and bits 0-7 results in the selection of the OTM1 circuit and the selection of the eighth Nixie tube and bits 8-11 cause the display of digits zero on the eighth Nixie tube.

As the trainee now depresses key 2 (FIGS. 2 and 6) in the keyset 28, switches B, D of the key pad (FIG. 6) are operated and ground signals over conductors 424, 428 to decoder circuit 436 result in a signal output over "Key 2" conductor 440. Key 2 conductor 440 is connected to bit gate 197 in the word format circuit 191, and accordingly the code word 0000010 for Key 2 is output by the OTM output circuit 124 to the computer in the manner heretofore described.

Computer 50 respectively generates the word 000010000010, which bits 0-2 (000) result in the selection of the OTM1 unit, bit 3 (0) prepares the selection circuit for the Nixie tubes and bits 4-7 (1000) result in selection of Nixie tube 9 (the third tube of group 29) and bits 8-11 (0010) enable the display of digit 2 on the selected Nixie tube.

The trainee now depresses key 6 (FIGS. 2, 6) in key pad 29 which as shown by the truth table results in the operation of switches D, F (FIG. 6) and the output of signals over conductors 428, 432, to decoder 436, whereby a signal is output over Key 6 conductor 448 which is connected to word-forming bit gates 196, 197 to cause the OTM output circuit 124 to output the Key 6 code word 0000110 to the computer in the manner previously described.

Computer 50 thereupon generates and outputs the code word 000010010110 to effect display of digit 6 in the Nixie tube 10. The Nixie decode circuit 134 (FIG. 10 in OTM1 responds to such word by providing a signal output over path 10-6 of the decoder circuit 476J (not shown) and thereby the energization and display of digit 6 on the fourth Nixie tube of the group 29.

After one-half second, the computer program generates four successive words for the purpose of effecting turnoff of the enerized ones of the Nixie tubes. Bits 0-7 of each of the four words now sent will be the same as those which were transmitted for the purpose of turning on the four Nixie tubes. However, bits 8-11 for each of the four words will now be 1100 which is a turnoff code for energized ones of the Nixie decoder circuit 476 (in this example 476G,H,I and J).

The computer 50 at this time further outputs the words for extinguishing the KP lamp 27 and KPGST lamps 20. The KP (green) code word 000101000010 and the KPGST code word 000100010111, are output successively over the data bus 80, and the lamp decode circuit 82 (FIG. 10) in the OTM1 module only decodes the same and via path 98 enables lamp storage circuit 96 (FIG. 11) to turn off the lamps 20, 27 in the manner of control previously described.

As the KP and KPGST lamps go dark, the training program requires the trainee to depress the time start key 26 (FIGS. 2 and 6) within a predetermined measured time period. As the trainee depresses time start key 26 (FIG. 6) ground is applied over conductor 480 which is connected to bit gates 193, 195 in the word format circuit 191 to cause the OTM1 output circuit 124 to output the time start code 0101000 to the computer 50.

In the event that the trainee does not depress the key 26 within a predeterined programmed time (i.e., code word 0101000 is not received within a given time interval after the codes which were transmitted to turn off the KP and KPGST lamps) computer 50 will generate an incorrect code signal (000111100100) to effect the illumination of the incorrect lamp 46 on the control panel 17. More specifically, the computer outputs the "incorrect" word 000111100100 over data bus 80, the lamp decode circuit 82 (FIGS. 9, 10) in the OTM1 only decodes such word, and causes lamp storage circuit 96 (FIG. 11) to output a signal over conductor 482 in the manner previously described and path 83 (FIG. 1) to illuminate incorrect lamp 46 (FIG. 2A) on the control panel 17.

In addition to illuminating the incorrect lamp 46, computer 50 also interrupts its normal program and shifts to an error routine for the purpose of causing the computer program to back up to the beginning of the step in which the error occurred, and simultaneously provides a signal to cause the audio tape unit 105 to back up the tape to the beginning of the corresponding step.

More specifically, computer 50 outputs the back audio step word (000111101011) over the data bus 80, and lamp decode circuit 82 (FIGS. 9, 10) in OTM1 only decodes such word and causes lamp storage circuit 96 (FIG. 11) to output a signal over "Repeat Step" conductor 486 (path 102--FIG. 1). The signal over repeat step conductor 486 is input to the audio tape control circuit 103 (FIG. 14) and over OR gate 342 and amplifier 344, OR gate 346 and transistor 348 to the Run conductor 349 as in the previous example. In addition, the same signal input over conductor 486 is fed over conductor 488 to an input on OR gate 490 and over output path 492 and amplifier 494 to the "Mute" output conductor 496 which is connected to the muting equipment on the audio tape unit 105.

The same input signal on conductor 486 is also input over conductor 498 and over OR gate 500 to the 0.3 second multivibrator 502 and also to one input of AND gate 504. The output of the multivibrator 502 as extended over output 506 acts as an inhibit to the operation of the AND gate 504 until such time as a 0.3 second interval has expired. With the expiration of such interval, the high level signal on conductor 506 causes AND gate 504 to be enabled, and the output thereof is fed to the inverter amplifier 508 and a first input on AND gate 510. The second input to AND gate 510 is connected to the output of the Stop On Tone gating circuit 512 which does not provide an inhibit signal at this time. The output of AND gate 510 is fed to an input on OR gate 514 and also to an inverter amplifier 516, the output of which is connected to one input on OR gate 518. The second inputs of OR gates 514, 518 are connected respectively over conductors 520 and 522 to terminals on the audio tape unit 105 which indicate the direction of travel of the tape as forward or reverse respectively. The Panasonic Audio Tape Unit Model No. 272S used as unit 105 in one embodiment includes such sensing terminals.

The outputs of OR gates 514, 518 thus effectively indicate to the system the particular direction that the tape unit is operating at any given time. The output of gates 514, 518 is fed over OR gate 524 to amplifier 526 and conductor 528 which is connected to the Reverse terminal of the audio tape unit 105. Diode 530 connected in the emitter circuit of amplifier 526 insures that the base of the transistor will be more negative than the emitter when a control signal is input to any of the three transistors 248, 494 and 526.

With application of the reverse signal to the audio tape unit 105, the direction of travel is tape reversed until the starting point of the step in which the error occurred is reached. The start of each step on the audio tape is marked with a 270 Hz tone and the end of each step is marked with 2700 Hz tone. In the present example, the step started with the audio output "26, Please" by the audio cassette to the trainee. It is now necessary therefore to back up the tape to the point at which said audio output will be repeated to the trainee. As the tape rewinds to the point at which the 270 Hz tone indicating the beginning of the step is detected, such tone is output over the recorder head of the tape unit 105 and fed over path 107 to the input of the audio tape control circuit 103 (FIG. 13) which signal being a 270 hertz signal passes over filter 356, and the path as previously described to enable latch reset 368 to output a control signal over step tone conductor 370 and amplifier 371 and Step Tone gate 372, amplifier 378, AND gate 380, and amplifier 386 to Stop on Step Tone conductor 420. Such signal via path 109 results in an output signal for interface 108 over 110 to the computer indicating that the tape is in a position to be stopped. It is noted at this time that since only three words are required from the audio tape control circuit 103 to the computer 50, the circuitry in interface 109 is hardwired in known manner to provide such word (and the two other words "Stop On Call Tone" and "Stop On Lesson Tone") as the corresponding conductor is energized.

Computer 50 responds to the receipt of the Stop on Step Tone word by outputting a tape stop word, and specifically by changing bit 4 of the back audio step word (which was previously output to run the tape in the reverse direction) from a logic 1 to logic 0. Such word is decoded by the lamp decode circuit 82 (FIGS. 9 and 10) in OTM1 only which enables lamp storage circuit 96 to remove the signal from Repeat Step conductor 486 to the audio tape control circuit 103 and thereby stop of the reverse operation of the audio tape unit 105. With the interruption of the signal on Repeat Step conductor 486 the enabling signal on Mute lead force 96 (FIG. 14) and the reverse signal on conductor 528 are also interrupted.

It is noted that as the tape reversed to place the system in a condition to repeat the step, the Step On Tone circuit 512 which has a first set of inputs connected to the repeat call conductor 485, repeat step conductor 486, and repeat lesson conductor 487, and a second set of inputs connected via amplifiers 371, 373 to call tone and step tone paths 541 and 370, respectively, is gated to insure that an output signal occurs from a Stop On Tone gating circuit 512 only when a tone is being detected. It is apparent that with the control of the system such that the tape can only stop at the point of detection of the tone, the possibility of out of in sync condition is significantly minimized.

The output of the Stop On Tone gating circuit 572 is fed to AND circuit 352 which has a second input connected to a two second output signal on multivibrator 350. AND circuit 352 enables a 0.3 millisecond multivibrator in the provision of a second input to the OR gate 346 to insure that the run conductor 349 will be enabled until such time as tone is reached even though the request for the enabling signal on the run device input over OR gate 342 should be prematurely terminated. The output of the multivibrator 353 also insures that the tape is always moving in the forward direction at the time of a stop.

The Stop-OK signal output of multivibrator 353 is also ANDED by gate 588 with the "Tone Present" output of gating circuit 512 and the run signal of OR gate 346 and the resultant signal is fed over conductor 590 to latch 600 (FIG. 7) which outputs a signal over conductor 382 as an enable signal for the call tone and step tone gates 546 and 380 and lesson tone gate 576 (FIG. 14). Such circuit prevents against the application of a stop signal indication to the computer 50 at a time other than when the tone is actually being detected.

When the computer 50 receives a signal over path 420, 550 or 580, the interface 108 generates an OTM reset signal which is transmitted back over path 602 (FIG. 7) and inverter amplifier 604 to one input of AND gate 606 which has its second input connected to the output of latch 600. An output signal is thus provided to the multivibrator 608, and after 500 milliseconds, the output of multivibrator 608 effects the reset of latch 600.

The output of the multivibrator 608 is also extended over tone reset conductor 610 to OR gate 612 (FIG. 13) and latch reset circuits 368 and 540 in the step tone and call tone channels. The latch reset circuits 368 and 540 also have an alternative reset which is applied at their output circuits respectively over conductors 614 and 616 to a 0.5 second multivibrator 618 which, after 0.5 seconds, outputs a signal over differentiating circuit 620 to a second input on gate 612 and thereby insures reset within a given time period.

As the step is now repeated, the trainee responds and assuming that the proper response is received in the allotted time period, computer 56 will provide a word output over data bus 80 to change the time start lamp 26 to the green light condition. Such operation requires that the computer provide a first output word for the purpose of turning off the red time start lamp, and immediately thereafter a second output word for causing the time start lamp to be illuminated green.

Briefly, the computer 50 first transmits the "Turnoff Red" code word 000100111100 for the red time start lamp over data bus 80 and lamp decode circuit 82 (FIGS. 9, 10) in OTM1 enable lamp storage 96, 98 to cause turnoff of the red lamp on time start key 26 via conductor 397. Immediately thereafter the computer 50 sends out the "Turn on Green" time start lamp code word (000110111101), and the circuitry operates in a similar manner to provide an enabling signal over conductor 399 to effect the turn on of the green lamp in time start key 26.

Computer 50 after a brief interval now outputs word 000111100101 over data bus 80 for the purpose of turning on the audio and effecting the output of one ring to the operator headset. Loop decoder circuit 82 (FIGS. 9 and 10) in OTM1 decodes the word and enables lamp storage 96 (FIG. 11) to provide an output signal over Start Audio conductor 340 as before to Audio Tape Control Circuit (FIG. 14) which responsively applies an enable signal to Run conductor 349 and the audio tape unit 105. As the tape advances, the ring tone recorded on the tape is output over path 112 to the headset of the operator 114, and also over path 107 to the input of the audio tape control circuit 103 (FIG. 13) which operates in the manner described before. Since the one ring is the terminating step of the call, the call tone on the tape will be a 2700 hertz signal. As such signal is fed over conductor 107, filter 354 passes such signal over conductor 532 to amplifier 534. The signal output of amplifier 534 is rectified by rectifier 536 and fed to transistor 538 and latch reset 540. Latch reset circuit 540 operates in the manner of latch reset circuit 368 to output a signal over call tone conductor 541 and over inverter amplifier 373 to call tone AND gate 542, which outputs a signal over amplifier 544 and one input of AND gate 546, which not being inhibited at this time, passes the signal over inverter amplifier 548 and Stop on Call tone conductor 550 to the interface 108 which responsively outputs a signal to the digital computer 50 indicating the tape may be stopped as a result of a call tone detection.

The computer 50 responsively changes the bit 4 of the original Start Audio code word from logic 1 to logic 0 (i.e., the code word is now changed to 000101100101) and the OTM1 lamp decoder and storage circuits 82, 96 (FIGS. 9-11) operate in the manner described to remove the signal from conductor 340 to terminate the advance of the tape by the audio tape unit 105.

At this point in the call (FIG. 4, line 9) the trainee is required to depress the position release key 30 for the purpose of releasing the call. With reference to FIG. 6, the position release key 30 as operated applies ground over conductor 552 to bit gates 193, 195, 197 to provide Position Release code word 0101010 output by OTM output circuit 124 to the computer 50.

With the receipt of such word, computer 50 successively generates calling area code 0001000000000, the hotel station code 00010010100, station paid code 000100100111, the T and C code 000100100100, the CDL code (loop 1) 000101001011, the ACS code (loop 1) 000101011001, and time start code 000100111100. Such codes as transmitted over the data bus 80 are detected at the lamp decode circuit 82 of the OTM1 unit which responsively causes lamp storage circuit 96 to turn off such lamps. At this time, one training call for a hoel + station paid call has been completed. As indicated above, each lesson includes a plurality of such calls which vary in the manner of calls received on a toll service board in the field to thereby provide the trainee with increased exposure during the training period.

Certain of the keys, such as the SR key 17 (FIGS. 2 and 6) on the TSD board are alternate action or on-off keys; that is, when the key is depressed it stays in the depressed condition, and when moved to the outward position, it remains in such position. The operation of such keys, i.e., the time of opening and the time of closing, is necessarily detected to provide proper indications of the condition of the keys to the system. Accordingly, each such key such as SR (FIG. 6) includes a resistor 554 connected to +5 volt battery and over amplifier 556, and differentiator 560 to one input of OR gate 562, and also over differentiator circuit 558 to the second input on OR gate 562. The output of OR gate 562 is connected over amplifier inverter 564 to a latch storage circuit 556 which is commercially available as a TTL-7400. The output of the latch storage circuit 566 changes in accordance with the condition of the associated one of the alternate action keys. That is, when the key such as SR is closed, the differentiating circuit 558 provides a pulse over OR gate 562 and amplifier to the latch storage circuit 566, which causes the latch circuit 566 to latch and provide a low level output signal over conductor 568. The output of amplifier 564 is also connected over OR gate 570 to the input of a 30 ms. multivibrator 572 and a differentiating circuit 574 to provide a reset signal for the latch storage circuit 566 after the expiration of a 30 ms. period.

When the key switch SR is opened, the pulse output over amplifier 556 and differentiating circuit 558 results in a pulse over OR gate 562 of amplifier 564 to the latch storage circuit 566 which latches and provides a low level signal over conductor 568 for the period of 30 ms. at which time the reset circuit including OR gate 570, multivibrator 522 and differentiator circuit 574 are operative to reset the latch 566.

The output of each alternating action key, such as SR, is connected to the bit gate word format circuit 191 to provide correspondingly different code words. The SR switch, for example, with each operation (as closed or opened) is completed to gate 192 only and accordingly will effect output of code word 1000000 to the computer 50.

The start of each tape used with the audio tape unit 105 has dual tone signals recorded thereon which are comprised of the 2700 htz and 270 htz signals (the call and step tone frequencies) for the purpose of providing a synchronization for the tape. That is, as the tape is inserted preparatory to a search for the desired lesson, the movement of the tape in the search will cause the two tones to be applied over path 107 (FIG. 13) to audio tape control circuit 103 and the two filter circuits 354, 356 via the associated output paths place a signal on the step tone conductor 370 and pulse tone conductor 541 which are output over inverter amplifiers 371, 373 to the lesson tone gate 374. The output of lesson tone gate 374 is ANDED over gate 576 and amplifier 578 to Stop on Lesson tone conductor 580. Such signal over path 109 to interface 108 results in the code word output to digital computer 50 as described before which indicates that the tape may be stopped at such point.

As noted above, the main function of the software system is to control the execution of a set of lessons for the Toll Service Desks (TSD). Each lesson consists of the PDP-8 computer 50 executing a predetermined set of commands to the TSD, such as lighting a specific group of lamps, or starting the audio unit, and then waiting for a response from the TSD. When the response arrives, the program checks to see if the response is correct; if so, the program advances to the next step in the current lesson; however, if the response is incorrect, the program lights the error lamp on the control panel, and repeats the current step. All eight TSD boards may be operating at the same time on either the same lesson or different lessons.

In order to control the above process, the software system consists of the following sets of routines:

1. Executive Routines: The Executive Routines control the overall flow of the system.

2. Lesson Routines: The Lesson Routines contain the instructions to control the execution of each lesson.

3. General Routines: The General Routines contain the instructions to execute the functions common to all the Lesson Routines.

Below is a brief description of each routine in the CBTS software system.

1. INT -- INT initializes all tables, clears all interrupts, and starts the system.

2. INTP -- INTP is the interrupt processor for the system. When an interrupt occurs INTP processes the interrupt.

3. OUT -- OUT transfers the code in the AC to the TSD board.

4. WAIT -- Wait picks up the wait count value in the AC and places it in the RCT wait count field.

5. DISPAT -- DISPAT checks each RCT to see if the active flag is set; if so the remote is scheduled for execution.

6. TASKSW -- TASKSW sets up the next instruction address in the RCT and waits for the interrupt.

7. GETINP -- GETINP gets the last interrupt from the input buffer and loads it into the AC.

8. tsd -- tsd handles all interrupts from the TSD board.

9. TIMER -- Timer checks each Timer field in the RCT to see if it is set; if so, it decrements it by one, checks for zero and schedules the

10. NORM -- Norm places the interrupt from the TSD in the input buffer.

11. RCR -- RCR processes the repeat call key on the control panel.

12. RESET -- Reset resets the input buffer pointer to the beginning of the buffer.

13. RESBUF -- Resbuf resets the active flag, repeat step, repeat call, repeat lesson flags in the RCT.

14. rlr -- rlr processes the Repeat Lesson key on the control panel.

15. RESDF -- RESDF loads the DATA Field that the lesson is loaded in the TASFSW DATA Field in the RCT.

16. clock -- clock routine update, the time of day clock on each TSD.

17. error -- error routines processes an error condition on the TSD.

18. rsr -- rsr processes the repeat step key on the control panel.

19. FLASH -- Flash routines flashes any lamps that are in the flash table for each RCT.

20. strtr -- strtr processes the start key on the control panel.

21. CASS -- CASS handles the loading of the lessons from the digital tape cassette.

22. BRIDGE -- Bridge handles the interface for the lessons from BANK 1 to BANK 0 of the memory on the PDP-8.

The lesson routines are made up of calls to the general routines for each lesson. Each lesson is unique and is simply a combination of lighting lamps and playing the audio, and checking responses.

1. UPSTEP -- Upstep updates the RCT with the ADDRESS of the current step in the lesson.

2. UPCALL -- Upcall updates the RCT with the ADDRESS of the current call in the lesson.

3. ASTOP -- Astop checks the code passed in the AC to see if it was an Audio Stop Code.

4. TONE -- Tone routines turn off the tone bit for the remote.

5. AUDOFF -- Audoff routine turns off the Audio play bit for the remote.

6. KEYRNT -- Routines checks for the TSD key passed as a parameter when the next interrupt comes in. No error time is set.

7. CLKON -- CLKON sets the clock flag in the RCT to 1.

8. CLKOFF -- CLKOFF sets the clock flag in the RCT to 0.

9. DELAY -- Delay sets the timer field in the AC to the value passed in the AC.

10. save1 -- save1 routines saves the return address for lesson subroutines.

11. REST1 -- REST1 restores the return address for lesson subroutines.

12. ZARSPF -- ZARSPF zeros the audio response flag in the RCT.

13. sarspf -- sarspf sets the audio response flag in the RCT to 1.

14. GARSPF -- GARSPF loads the audio response flag in the AC.

15. loff -- loff routine turns off the lamp passed to it in the AC.

16. lon -- lon routine turns on the lamp passed to it in AC.

17. save4 -- save4 saves the return address in the RCT for general routines that do not wait.

18. REST4 -- REST4 restores the return address in RCT for general routines that do not wait.

19. SAVE -- SAVE saves the return address in RCT for general routines that wait.

20. RESTOR -- RESTOR restores the return address in RCT for general routines that wait.

21. SAVP1 -- SAVP1 saves the parameter passed to it in AC in RCT.

22. retp1 -- retp1 restores the parameter from the RCT into AC.

23. mclrgo -- mclrgo master clears the board and turns on the go lamp.

24. WAST -- WAST checks to see if the audio has stopped; if not, WAST waits for the audio to stop.

25. ZASTPF -- ZASTPF zeros the audio stop flag.

26. SASTPF -- SASTPF sets the audio stop flag to 1.

27. GASTPF -- GASTPF loads the AC with the audio stop flag.

28. KEYR -- KEYR sets the error count to 5 seconds and waits for the key passed to it in AC.

29. wlon -- wlon waits 5 seconds and then turns the lamp passed to it in the AC on.

30. WLOFF -- WLOFF waits 5 seconds and then turns the lamp passed to it in AC off.

31. DTIME -- DTIME displays the time passed to it on the TSD board.

32. ARKEY -- ARKEY plays the audio and waits for the key passed to it to be depressed.

33. SAKEY -- SAKEY plays the audio and waits for the key passed to it to be depressed and the verbal response to come in.

34. RKEY -- RKEY waits for the key passed to it to come in and the verbal response.

35. SAUDIO -- SAUDIO plays the audio unit and waits for it to stop.

36. RESP -- Resp sets the response time for a verbal response and wait for the response to come in.

37. WVRSP -- WVRSP waits for the verbal response to come in; if it has already come in, routine returns to calling routine.

38. INCOFF -- Routine turns off all lamps on the TSD board.

39. MUTON -- Routine mutes the aduio and returns to the lesson.

40. MUTOFF -- Routine turns off the mute bit for the audio unit.

41. DISPLY -- DISPLY displays in the NIXIE Lamps the number passed to it.

42. DOFF -- DOFF blanks the NIXIE blanks.

43. KEYPUL -- KEYPUL handles the digits keyed in from the TSD keyboard; if the digit is the proper key it displays it on the NIXIE lamp.

44. FLHON -- FLHON places the lamp code passed to it in the flash queue.

45. FLHOFF -- FLHOFF eliminates the lamp code passed to it from the flash queue.

The logic flow of the CBTS software system is separated into two parts. The first part is the Executive Control portion which controls the internal processing of the system and the second is the Interrupt Processor which controls the Input/Output portion of the system.

1. START -- In any of the following steps jump to error routine if incorrect response is made.

2. Turn on lamps:

Cac, hotel STA, KP GST, STA PAID (green), Release FWD, T&C, Loop 1 CLD, Loop 1 ACS, TIME ST Red.

3. One half second later turn OFF release FWD.

4. start audio

5. Check for speech present, and KP GST Actuation, and audio stop.

6. When KP GST has been depressed turn ON KP Red for 1/2 second then turn KP Red OFF and turn KP Green ON.

7. start audio.

8. Detect keypulse "0," then "0," then 2, then 6 and display until after #6 key has been depressed. Turn OFF displays, KP, and KP GST; and audio stop.

9. Detect TIME ST Key depression. Turn TIME ST (Red) OFF. Turn TIME ST (Green) ON.

10. start audio.

11. Check for POS Release actuation.

12. After POS Release actuation, turn OFF Audio, CAS, Hotel STA, STA PAID, T&C, Loop 1 CLD, Loop 1 ACS, TIME START (Green).

13. Lesson is complete -- STOP. ##SPC1## ##SPC2## ##SPC3## ##SPC4## ##SPC5## ##SPC6## ##SPC7## ##SPC8## ##SPC9## ##SPC10## ##SPC11## ##SPC12## ##SPC13##