Electronic Musical Scale and Chord Display Apparatus

This invention relates to the art of stored program display apparatus, and more particularly to portable apparatus for displaying selected combinations of information quantities.

One area of use of the present invention is in displaying selected combinations of information quantities such as the musical notes of scales and chords, although the principles of the invention can be variously applied. Devices have been proposed as musical teaching aids, many of which are relatively large in size and are for mounting on an instrument in registration with the keys thereof. Others provide only a limited amount of information to the user. Accordingly, it would be highly desirable to provide a portable, hand-held device which automatically generates and displays any combination of musical scales and associated chords selected by the user.

It is, therefore, a primary object of the present invention to provide a new and improved apparatus for displaying selected combinations of information quantities such as musical notes of scales and chords.

It is a further object of the present invention to provide such apparatus of the stored program type which automatically generates and displays combinations of information quantities such as musical notes of scales and chords selected by the user.

It is a further object of this invention to provide such apparatus which is small in size and light in weight so as to be portable and hand-held.

It is a further object of invention to provide such apparatus which is relatively convenient and economical to manufacture.

The present invention provides apparatus for displaying selected combinations of information quantities such as musical notes of scales and chords. A plurality of manually operated selector elements are provided on a small, light weight, portable hand-held housing. Combinations of information quantities such as musical notes of scales and chords are selected by manual operation of the various selector elements which in turn is converted by logic circuiting into coded logic signals transmitted to storage means including read only memory elements. The storage means, in turn, provide signals which are applied to appropriate ones of a plurality of display elements on the housing for activating the elements to display the musical notes of a selected scale or chord.

The foregoing and additional advantages and characterizing features of the present invention will become clearly apparent upon a reading of the ensuing detailed description together with the including drawing wherein:

FIG. 1 is a perspective view of apparatus according to the present invention for displaying selected combinations of information quantities such as musical notes of scales and chords;

FIG. 2 is a layout view illustrating the selector elements and display elements of the apparatus of FIG. 1;

FIG. 3 is a schematic block diagram of the apparatus of the present invention;

FIG. 4 is a schematic diagram further illustrating the scale coding means of the apparatus of FIG. 3;

FIG. 5 is a schematic diagram further illustrating the chord coding means of the apparatus of FIG. 3;

FIG. 6 is a schematic diagram further illustrating the chord modification coding means of the apparatus of FIG. 3;

FIG. 7 is a schematic diagram further illustrating one portion of the storage means of the apparatus of FIG. 3; and

FIG. 8 is a schematic diagram further illustrating another portion of the storage means of the apparatus of FIG. 3.

Referring now to FIG. 1, there is shown a device according to the present invention for displaying selected combinations of information quantities such as musical notes of scales and chords. The device comprises a housing generally designated 10 which is small in size and light in weight so as to be portable. Housing 10 preferably is of suitable plastic material and typically would have a length of about five and one-helf inches, a width of about three and one-half inch and a thickness of about one inch. The apparatus of the present invention further comprises display means on the housing 10 for providing a visual display of the selected information quantities and combinations thereof. In the present instance there is provided a first display portion or region 12a for displaying the notes of selected musical scales and a second display region or portion 12b for displaying notes of selected musical chords. The display portions 12a and 12b illustrated in FIG. 1 are elongated rectangular in overall shape, and portion 12a is slightly greater in overall length as compared to portion 12b.

The apparatus of the present invention further comprises selector means in the housing 10 and including manually operated selector elements in the form of pushbutton switch actuators 14 for selecting particular combinations of the information quantities. For example, in the illustrative arrangement of FIG. 1, there is a group of push buttons generally designated 14a for selecting a number of musical scales, a second group of push buttons 14b for selecting a number of musical chords, and a third set of buttons 14c for modifying selected chords. Another push button 15 is provided to clear the system in a manner which will be described in detail and another push button 16 serves as an on-off electrical power control switch.

The apparatus of the present invention further comprises storage means in the housing 10 for storing the information quantities, i.e. electrical representations of the information quantities, and which is operatively connected to the display means 12. The nature and operation of the storage means will be described in further detail presently. The apparatus of the present invention also includes circuit means in housing 10 and operatively connected to the selector means, the storage means and the display means. The circuit means is operative in response to manipulation of the push buttons 14 of the selector means to fetch or obtain from the storage means signals representative of the selected information quantities and combinations thereof and to utilize the signals to operate the display means 12 to provide a visual display of the selected information quantities and combinations thereof. The construction and operation of the circuit means will be described in further detail presently.

Referring now to FIG. 2, the layout or format of the displays 12 and selector elements 14 is illustrated in further detail.

The selector elements or push buttons in the group designated 14a serve to select musical scales for display, there bein fifteen buttons 14a shown in FIG. 2, with the appropriate identifying indicia corresponding to the various scales. The chord selector elements or push buttons 14b are ten in number, with the letter T on one button standing for triad and the remainder of the buttons being for the sixth, seventh, etc. chords and further including minor and diminished variations. The four chord modification buttons 14c are designated minor, suspended, augmented and diminished as indicated by the letters M, S, A and D, respectively, in FIG. 2. After a musical scale or chord is displayed and it is desired to select and display a new quantity, the clear button 15 is depressed.

The upper display region or portion designated 12a in FIGS. 1 and 2 is for displaying the notes of a selected scale. As shown in FIG. 2 there are eight separate display elements or modules in the portion 12a, each being of the alphanumeric light emitting diode type as will be described in further detail presently. Each display module, in turn, is divided into two areas or regions, the lower one as viewed in FIG. 2 providing a visual representation of the letter of the alphabet corresponding to a musical note and the upper area or portion as viewed in FIG. 2 providing a visual indication of a sharp or flat as will be described in further detail presently. Thus in response to designation of a selected musical scale by means of an appropriate one of the selector elements 14a the eight letters corresponding to the musical notes of the scale are displayed across the display portion 12a. Directly above certain ones of the letters there will be a visual indication or a sharp or flat. In a similar manner, the chord display portion 12b comprises seven display modules or elements each being of the same type which is included in the display portion 12a. The display modules in the group 12b also are provided with appropriate sharp and flat designations as shown in FIG. 2. Thus, in response to selection of a desired chord by operation of the appropriate selector element 14b, the letter representations of musical notes are displayed across the portion 12b for the selected chord, and where appropriate particular letters will have the sharp or flat designation thereabove.

Refering now to the system block diagram of FIG. 3, a plurality of electrical switch arms designated 14a are shown corresponding to the scale selector elements or push buttons 14a extending from the housing 10. The switches are normally open, and one side or end of each switch is connected electrically to a line 20 which, in turn, is connected to a source of bias or reference voltage (not shown). The other side or end of each switch is connected by an electrical line to a corresponding input of a coding circuit designated 22 in FIG. 3. Thus, there are fifteen switches each containing one of the switch arms 14a and each connected by a corresponding line to one of fifteen inputs of the circuit 22. The coding circuit 22, in turn, includes a network of diodes, flip-flops and other components which will be described in further detail presently. Only one of the switch arms 14a will be closed at any given time thereby applying a signal or voltage input to one of the input terminals of the circuit 22. Depending upon which of the inputs is energized, a coded four bit binary word is present on the four output lines 24-27 leading from circuit 22. In other words, each bit of the four bit word is present as a logical signal, i.e. high or low discrete signal level, on a corresponding one of the lines 24-27.

There is also provided a plurality of normally open electrical switches corresponding to the chord selector elements or push buttons 14b extending from the housing 10. In particular, there are ten switches each containing one of the switch arms 14b included in the circuit of FIG. 3, and one side or end or each switch is connected by an electrical line to the bias or reference voltage line 20. The other end or side of each switch is connected by a corresponding electrical line to one of ten inputs of a coding circuit generally designated 30. Only one of the ten switch arms 14b will be closed at any given time to select a particular chord to be displayed, and depending upon which arm is closed a corresponding one of the inputs of coding circuit 30 will be energized. Circuit 30, like coding circuit 22 includes a network of diodes, flip-flops and other components to be described in detail presently, and the circuit 30 provides a coded four bit binary word on the four output lines 32-35 leading from the circuit.

The arrangement of FIG. 3 also includes four normally open electrical switches corresponding to the four selector elements or push buttons 14c extending from the housing 10. One side or end of each of the switches is connected by a corresponding electrical line to the reference voltage line 20, and the other side or end of each switch is connected by a corresponding electrical line to one of four inputs of a coding circuit generally designated 38. Only one of the switch arms 14c will be closed in any given time as determined by the particular chord modification desired, and depending upon which switch arm 14c is closed a corresponding one of the four inputs of coding circuit 38 is energized. Circuit 38, in turn, provides a three bit coded binary word present on three output lines 40-42 extending from the coding circuit 38. Circuit 38, which will be described in detail presently, includes a network of diodes, flip-flops and other components similar to coding circuits 22 and 30. A system clock 44 is connected by means including a line 46 to each of the coding circuits 22, 30 and 38 for supplying timing pulses thereto.

The system of FIG. 3 further comprises storage means for storing the information quantities, i.e. electrical representations of the information quantities. In particular, the storage means comprises scale logic means for converting the coded binary word on lines 24-27 into electrical signals needed to select and to operate appropriate components of the scale display means 12a. For convenience in further description, the four inputs to the scale logic means 48 also are designated X1, X2, X3 and X4. The scale display means 12a includes a plurality of display components or modules 51-58 which for convenience in further discussion also are designated YO1-YO8. The display modules are eight in number corresponding to the eight notes of a musical scale, and each is of the dot matrix alphanumeric type wherein input electrical signals provide row and column information for selecting the desired character to be visually displayed. Each display module has six input terminals which are labeled A1-A6 in FIG. 3. The nature and operation of the display modules 51-58 will be described in further detail presently. In the present illustration, the inputs A1, A2 and A3 of each of the display modules 51-58 are connected by corresponding electrical lines to various outputs of the scale logic means 48. In particular, there are eight cables designated 59-66 in FIG. 3 connecting display modules 51-58, respectively, to logic means 48, each cable in turn containing three wires for making connection between the A1, A2 and A3 terminals of the particular display module to terminals of logic means 48.

The scale display 12a also includes a corresponding plurality of auxiliary display elements 71-78, there being one auxiliary or additional display elements corresponding to each of the display elements 51-58. The display elements 71-78, when appropriately signalled or energized, provide visual representations of sharps or flats associated with particular notes wherever necessary as determined by scale which has been selected. A cable 80 containing a plurality of lines i.e. two for each of the additional displays for a total of sixteen, connects the scale logic means 48 to the additional display elements 71-78. A line 82 connects the source of bias or reference voltage to each of the additional display elements 71-78. A line 84 connects an output of the scale logic means 48 to the terminal designated A6 of each of the display elements 51-58 for the purpose of conducting a clear signal to each of the displays. In the present illustration, the terminals designated A5 and A6 of each display element 51-58 are connected together and to a source of voltage.

The storage means in the system of FIG. 3 further comprises chord logic means 90 which, in a manner similar to that of the scale logic 48, converts an input binary word representing a selected chord into a number of electrical signals for selecting and energizing appropriate components of the chord display means 12b. The lines 32-35 leading from the output of the coding means 30 are connected to corresponding inputs of the logic means 90, and for convenience in further discussion the four inputs to logic means 90 are designated X5, X6 and X7 and X8. In addition to receiving coded information as to the selected chord to be displayed, the logic means 90 receives scale information indicative of the musical key for the chord by means of lines 92, 93, 94 and 95 which connect the coded output lines 24, 25, 26 and 27 of the coding means 22 to four inputs of the chord logic means 90. These inputs also are identified with the characters X1, X2, X3, and X4 associated with the scale logic means 48 to facilitate further discussion. The binary output of the coding means 38 for chord modification is connected by lines 40-42 to three corresponding inputs of the chord logic 90. The inputs also are designated X9, X10, and X11 for convenience in further discussion.

The chord display means 12b includes a plurality of display modules or elements, in particular seven components 99-105 which are also labeled Y09-Y15 in FIG. 3. The display elements 99-105 are dot matrix alphanumeric display modules similar to the modules 51-58. The six input terminals of the display modules 99-105 are labeled A1-A6, and a three wire cable connects the A1, A2 and A3 input terminals of each display module to corresponding outputs of the chord logic means 90. These cables are designated 107-113 in FIG. 3. The terminals designated A4 and A5 of each display are connected to a supply voltage source, and the input terminals designated A6 of each module are connected by a line 116 to a clear signal output of the chord logic means 90. The chord display means 12b also includes a plurality of additional or auxiliary display elements 119-125 which, like the additional displays 71-78, provide visual indications of sharps and flats for the various notes depending upon the particular chord which is selected. A cable designated 128 containing a plurality of leads connects the chord logic means 90 to the additional display modules 119-125. Each module also is connected by a line 130 to a supply voltage source.

FIG. 4 illustrates in further detail the coding means generally designated 22 in the circuit of FIG. 3. The coding circuit includes a diode network constructed in the manner shown in FIG. 4. The fifteen scale select switches 14a including corresponding switch arms are shown each connected electrically in series between the reference voltage line 20, in the present illustration being connected to electrical ground, and the diode network. Adjacent each switch in FIG. 4 there is provided the musical scale identification to facilitate illustration and discussion. The output of the diode network comprises four output lines designated 140-143 which are connected to the inputs of four filter networks 145-148, respectively. The filters 145-148 each can comprise, for example, a resistance-capacitance network. The outputs of filters 145-148, in turn, are connected by lines 150-153, respectively, to four logic circuit elements 155-158 of the type known as inverters.

The circuit of FIG. 4 further includes four logical flip-flop elements of the D type designated 160-163. Lines 150-153 are connected by lines 165-168, respectively, to inputs of the flip-flops 160-163. A line 169 connects a source (not shown) of positive bias voltage, for example about five volts positive, to appropriate inputs of the flip-flops 160-163. Output terminals of the four flip-flops 160-163 are connected to corresponding ones of the output lines 27, 26, 25 and 24, respectively, of the system as illustrated in FIGS. 3.

The outputs of inverters 155 and 156 are connected by lines 172 and 173, respectively, to the two inputs of a NOR logic circuit component or gate 175. Similarly, the outputs of inverters 157 and 158 are connected by lines 177 and 178, respectively, to corresponding inputs of a NOR gate 180. The outputs of gates 175 and 180 are connected by lines 182 and 183, respectively to inputs of a NAND gate 185, the output of which is connected generally designated 187. The output of the multivibrator circuit 187 is connected by a line 192 to one input of a NOR gate 194. The other input of gate 194 is derived from a circuit including the clear switch 15 previously described which is connected between the reference voltage line 20 and the input of a filter 196 identical to the filters 145-148, the output of which is connected through an inverter 198 to the other input of gate 194. The output of gate 194 is connected through an inverter 200 to one input of a NOR gate 202. The other input of NOR gate 202 is derived from a circuit including the series combination of a resistor 204 and capacitor 206 connected between the source of positive bias voltage, for example five volts positive, and ground. The junction between the resistor and capacitor is connected through an inverter 208 to both inputs of a NAND gate 210, the output of which is connected to the input of a multi-vibrator circuit generally designated 212. The output of multi-vibrator 212 is connected to the other input of the gate 202. The output of gate 202, in turn, is connected by a line 218 to corresponding input terminals of the D flip-flops 160-163.

FIG. 5 illustrates in detail the coding means generally designated 30 in the system of FIG. 3. The coding means includes a network of diodes connected in the manner shown in FIG. 5, and the switch arms 14b of the ten chord selector switches are connected each in series between the reference voltage line 20 and a corresponding input line to the diode network. The various type chords selected by the switches 14b are labelled in FIG. 5. The diode network, in turn, is connected through four output lines 220-223 to the inputs of four filters 225-228, respectively, which are identical to the filters 145-148 of FIG. 4. The filters 225-228, in turn, are connected by lines 230-233, respectively, to the inputs of four inverters 235-238, respectively.

The circuit of FIG. 5 further includes four flip-flops 240-243 of the D type similar to flip-flops 160-163 in the circuit of FIG. 4. Lines 230-233 are connected by lines 245-248, respectively, to inpus of the flip-flops 240-243. A line 249 connects a source (not shown) of positive bias voltage, for example five volts positive, to another input of each of the flip-flop circuits 240-243. An output terminal of each of the flip-flop circuits 240-243 is connected to a corresponding one of the output lines 32, 33, 34 and 35, respectively, of the system as illustrated in FIG. 3. The outputs of inverters 235 and 236 are connected by lines 252 and 253, respectively, to the inputs of a NOR gate 255. Similarly, the outputs of inverters 237 and 238 are connected by lines 257 and 258, respectively, to the inputs of NOR gate 260. The outputs of gates 255 and 260, in turn, are connected by lines 262 and 263, respectively, to the inputs of a NAND gate 265. Gate 265 is connected to the input of a multi-vibrator circuit generally designated 267. The output fo multi-vibrator 267 is connected by a line 272 to one input of a NOR gate 274, the other input of gate 274 being connected by a line 276 to a location in the system providing a CLRI signal which will be identified presently. The output of gate 274 is connected by a line 276 to an appropriate input of each of the flip-flop elements 240-243.

FIG. 6 shown in further detail the coding means designated 38 in FIG. 3. The coding means includes a diode network connected as shown in FIG. 6, and the four selector switch arms 14c are connected in series between the reference voltage line 20 and input lines to the diode network. The circuit of FIG. 6 is provided with identifying indicia adjacent the switches referring to the various chord modifications for convenience in illustration. The outputs of the diode network are connected by three output lines 281-283 to the inputs of filters 286-288 which are identical to the filters 145-148 and 225-228 of the circuits of FIGS. 4 and 5. The outputs of filters 286 and 287 are connected by lines 290 and 291, respectively, to the inputs of inverters 295 and 296, respectively. The circuit of FIG. 6 also includes three logical flip-flop elements 298-300 of the D type similar to the flip-flops 160-163 and 240-243 of circuits of FIGS. 4 and 5. Lines 290 and 291 are connected by lines 302 and 303, respectively, to inputs of the flip-flops 298 and 299. Line 292 from filter 288 is connected to an input of the flip-flop 300. A line 305 connects a source (not shown) of positive bias voltage, for example five volts positive, to inputs of each of the flip-flops 298-300. The output terminals of the flip-flops 298-300 are connected to the lines 42, 41 and 40, respectively, as shown in the system of FIG. 3.

The outputs of inverters 295 and 296 are connected by lines 308 and 309, respectively, to the inputs of a NOR gate 310. Gate 310 is connected to one input of a NAND gate 312, the other input of which is connected by a line 314 to the line 292. The output of gate 312 is connected to a multivibrator circuit designated 316, the output of which is connected by a line 318 to one input of a NOR gate 320. The other input of gate 320 is connected by a line 322 to a location in the system providing a CLR2 signal which will be identified presently. The output of gate 320 is connected by a line 325 to inputs of each of the flip-flops 298-300.

FIG. 7 shows in further detail the components of the scale logic means generally designated 48 in the system of FIG. 3. The scale logic means includes eight read only memory elements designated 331-338. For convenience in further discussion, the memory elements 331-334 and 336-338 also are designated IC1-IC4 and IC6-IC8, respectively, as indicated in FIG. 7. The memory elements 331-338 are of the programmable type and, one found to perform satisfactorily in the system of the present invention is available commercially under the designation 8223. For additional information on the nature and operation of memory elements 331-338 reference can be made to the article entitled "How To Program Read-Only Memories" by R. D. Pascoe in Popular Electronics, July 1975, pages 27-30.

As shown in FIG. 7, lines 24, 25, 26 and 27 leading from the coding means 22 of FIG. 3 are connected to corresponding inputs designated X4, X3, X2 and X1, respectively. The inputs X1, X2, X3 and X4 are connected by lines 340-343 to the input terminals designated A0, A1, A2 and A3 of each of the memory elements 331-338. Each memory element has eight output terminals designated B0-B7 in FIG. 7. As indicated by the legend in FIG. 7, lines from the output terminals of the memory elements 331-338 have particular destinations among the display modules Y01-Y15. For example, the output terminals B3, B4 and B5 of memory element 336, also designated IC6 in FIG. 7, are connected to the A1, A2 and A3 input terminals, respectively, of the display element Y02, also designated 52, in the display of FIG. 3.

FIG. 8 illustrates the chord logic means generally designated 90 in FIG. 3. The arrangement of FIG. 8 includes a plurality of read only memory elements similar to that of FIG. 7. In particular, there is a first read only memory element designated 350 which is of the 8223 type identical to the elements in FIG. 7. For convenience in further discussion, memory element 350 also is designated IC5. The arrangement of FIG. 8 also includes three read only memory elements designated 352, 354 and 356 which can be of the type commercially available from Electronic Arrays under the designation EA4600. For coneevience in further discussion, the elements 352, 354 and 356 also are designated IC9, IC10, and IC11. The memory elements 350, 352, 354 and 356 are programmable in a manner similar to that of the elements 331-334 and 336-338. As shown in FIG. 8, lines 32, 33, 34 and 35 leading from the coding means 30 of FIG. 3 are connected to the corresponding inputs X8, X7, X6 and X5, respectively. The inputs X5, X6, X7 and X8 are connected by lines 360, 361, 362 and 363, respectively, to the input terminals A4, A5, A6 and A7 of tach of the memory elements 352, 354 and 356. Lines 40, 41 and 42 leading from the coding means 38 of FIG. 3 are connected to the corresponding inputs X11, X10 and X9. The inputs X9, X10 and X11 are connected to the A8, A9 and A10 input terminals of each of the memory elements 352, 354 and 356. Lines, 92, 93, 94 and 95 leading from the coding means 22 of FIG. 3 are connected to the corresponding inputs X4, X3, X2 and X1. The inputs X1, X2, X3 and X4 are connected to the A0, A1, A2 and A3 input terminals of each of the memory elements 352, 354 and 356.

By way of example, each of the filters 145-148, 225-228 and 286-288 in the circuits of FIGS. 4, 5, and 6, respectively can comprise two series-connected resistors, each having a magnitude of about 510 ohms, the combination of resistors being connected between a source of positive bias voltage, for example 5 volts positive, and are terminal of a capacitor, the other terminal of which is connected to ground. The capacitor can have a magnitude of about 33 microfarads. The input of each filter is connected to the common connection of the resistors, and the filter output is connected to the junction of the resistor and capacitor. Inverters 155-158, 235-238 and 295, 296 in the circuits of FIGS. 4, 5 and 6, respectively, can be of the Texas Instruments type SN74L04 HEX inverters. Flip-flops 160-163, 240-243 and 298-300 in the circuits of FIGS. 4, 5 and 6, respectively, can be of the Texas Instrument type SN74L74 dual D-type edge-triggered flip-flops. Multivibrators 187, 276 and 316 in the circuits of FIGS. 4, 5 and 6, respectively, can be of the Texas Instrument type SN74L122 retriggerable monostable multivibrators with clear. The apparatus can be battery-operated.

The apparatus of the present invention operates in the following manner. The relatively small and lightweight housing 10 can either be held in the user's hand or placed on a suitable supporting surface such as the top of a desk or table. The apparatus automatically generates and displays any combination of musical scales and associated chords which the user desires. The scale display is selected by depressing any one of the fifteen musical key push buttons designated 14a in FIGS. 1 and 2, also shown in FIGS. 3 and 4 and provided with the musical note designation. The apparatus codes the key selection into a four bit binary word in the form of logical signals on the lines 24, 25, 26 and 27 also designated X4, X3, X2 and X1, respectively, in FIGS. 3 and 4 by means of the diode array and arrangement of the D type flip-flop elements 160-163. In particular, one of the desired switch buttons 14a is depressed and the lines 150-153 in FIG. 4 switch to electrical ground. For example, the fourteenth switch in the network of FIG. 4, also designated G, is coded by the diode network to produce the condition 153 and 152 and 151 each equal to logical 0 and 150 equal to logical 1 when that push button switch is depressed. The monostable multivibrator 187 triggers on the negative edge of the input signal with either line 182 or 183 being at a low voltage level. The output pulse produced by multivibrator 187 then clears the flip-flop elements 160-163 forcing the output lines 27, 26, 25 and 24, respectively, to a low voltage or logical 0 level. When the selected push button is released by hand, the positive-going edge of the signals on lines 150-153 serve to clock the respective ones of the flip-flops 160-163 thereby setting them at a high or logical one level. For example, with the switch designated G in FIG. 4, the boltages on lines 153, 152 and 151 will go high on the release of the switch push button thereby setting the flip-flops 163, 162, and 161 all at a logical one level. Until the next key selection or until the clear switch is depressed, the states established for the lines 27, 26, 25 and 24 also designated X1, X2, X3 and X4 will be maintained. The foregoing is summarized in Table 1 wherein the first column identifies the fifteen scale select switches 14a by the appropriate musical notes and the remaining four columns show the resulting logical state of the lines designated X4, X3, X2 and X1 in FIG. 4.

The logical signals on the lines designated X1, X2, X3 and X4 are applied to the inpur lines A0-A3, respectively, of the read only memory elements 331-334 and 336-338 in the arrangement of FIG. 7, also designated IC1-IC4 and IC6-IC8. The memory elements are programmed such that the output lines B0-B7 of each element will change logical states in a predetermined manner. The program tables, also known in the art as truth tables, for each of these memory elements are included further on in the specification. The output lines of the memory elements are connected to the scale display modules or elements designated 51-58 and also Y01-Y08 in FIG. 3. In particular, the input terminals A1, A2, A3 and A6 of the display elements will have their states changed accordingly. The foregoing is illustrated further in Table 2 where the first four columns indicate the logical states of the lines X4, X3, X2 and X1 and the next eight columns indicate corresponding musical notes displayed by each of the scale display elements Y01-Y08. The last column on the right in Table 2 identifies by key note the musical scale which is displayed.

For example, on line two of table 2, for the condition of X1 being a logical one and the other lines X2-X4 being at the logical zero level, the scale of A is displayed with the notes shown from left to right at Y01-Y08.

Table 3 illustrates in further detail the operation of each of the display elements Y01-Y08.

In particular, the various logical states of inputs A1, A2, A3 and A6 are shown in the table and the last column shows the letter of the alphabet displayed corresponding to the particular musical note. Each of the display elements Y0-Y8, also designated 51-58 in FIG. 3, preferably is a 5 by 7 dot matrix alpha-numeric display module which contains its own character generator capable of displaying 64 ASCII characters wherein the character selection is achieved by presenting a six bit binary word at the module input. The six bit binary word corresponds to the inputs A1-A6 shown in Table 3 above. The display is a 5 by 7 array of light emitting diodes having a character height of about 0.350 inches. A typical commercially available display module is available from the Monsanto Company under the designation MDA111.

In the display of some musical scales it is necessary to provide an indication of a sharp of flat with various ones of the musical notes. This is provided by the additional or auxiliary display elements 71-78 shown in FIG. 3. The auxiliary display elements 71-78 are physically associated with the main display elements Y01-Y08, respectively, as illustrated in FIGS. 1 and 2. In other words, if the musical note letter displayed on element Y01 should have a flat displayed with it, this is done by the auxiliary element 71. As shown in FIG. 3 each of the elements 71-78 has a visible surface divided into four square sections of equal area, and in each element one of these sections is provided with a musical sharp symbol and the other with a musical flat symbol. The operation of the auxiliary scale display elements 71-78 in relation to the main scale display elements Y01-Y08 is summarized in Table 4.

The first four columns at the left show the various logical states of the quantities X1-X4. The next eight columns under the heading flat scale display indicate whether or not a flat will be displayed by the auxiliary display element corresponding to the main display element indicated in the table. Similarly, the last eight columns indicate whether or not a sharp will be displayed by an auxiliary display element associated with each of the main display elements. For example, referring to the second row of Table 4, with X1 having a logical one state and the remaining quantities X2-X4 having a logical zero state it is seen by referring back to Tables 1 and 2 that the scale of A is being displayed. From Table 4 it is seen that no flats will be displayed but that musical sharp indications will be made corresponding to the notes C, F and G displayed by the elements YO3, YO6 and YO7, respectively. Proceeding along with a similar analysis, the next row corresponds to display of the scale A flat wherein no sharps are displayed but wherein flats are indicated by the auxiliary display elements associated with the notes A, B, D, E, and A displayed by the elements YO1, YO2, YO4, YO5 and YO8, respectively. Each of the auxiliary display elements 71-78 can be of the type commercially available from the Monsanto Company designated red LED array MV5040. Each element of this type consists of four gallium arsenide phosphide diodes mounted in a single five-lead epoxy package. For the display of sharps and flats for musical scales, only two of the four visual areas are used. Use of the remaining two areas will be described further on in the specification.

By way of further illustration, referring to the foregoing example where the switch 14a corresponding to the musical key of G is depressed causing the state of X1 to be logical zero and the states of X2, X3 and X4 each to be logical one, the state of the module input lines and resulting display is summarized in Table 5.

The apparatus is operated to display the notes of a musical chord in the following manner. The chord display is selected by depressing any one of the ten push button switches designated 14b as shown in FIGS. 1-3 and 5, after having previously established a scale in the manner described above. The circuit of FIG. 5 including the diode array and D-type flip-flops 240-243 codes the chord selection into a four-bit binary word including the quantities designated X5, X6, X7 and X8 in FIG. 3 which are in the form of logical signals present on the lines 35, 34, 33 and 32, respectively. The overall operation is summarized by Table 6 wherein the four columns on the right indicate the logical states of the quantities X5, X6, X7 and X8 resulting from activation of the various switches indicated in the left-hand column.

Referring now in detail to FIG. 5, a selected one of the push buttons 14b is depressed after a scale selection has been completed. The lines 230-233 switch to electrical ground accordingly. For example, the switches designated 9D in FIG. 5 is coded to produce the condition of a logical zero on lines 230, 232 and a logical one on lines 231, 233. The monostable multivibrator 276 triggers on the leading edge, i.e. the high to low transition of the signals on lines 230-233, of the pulse created by depressing any one of the chord selection push buttons 14b. The multivibrator pulse then clears the flip-flops 240-243 forcing the output lines 32-35 to a low condition, i.e. the quantities X5-X8 each being a logical zero. When the selected push button is then released, the resultant positive-going edges of signals on lines 230-233 clock the respective flip-flops 240-243 setting outputs thereof to a high logical state. For the previous example of the switch designated 9D, lines 230 and 232 will go to a high level at the release of the push button thereby setting the respective flip-flops to a condition of X5 and X7 each being a logical one. Until the next scale selection, chord selection or clear push button is depressed the previous states or logic levels will exist. The input lines of the read only memory integrated circuits designated IC5, IC9, IC10 and IC11 in FIG. 8 will receive signals having logical levels of the quantities X1-X8. As determined by the respective truth tables or program tables of these memory elements, the output lines B0-B7 thereof will change state accordingly. As indicated in connection with the scale display, these tables will be presented further on in the specification. The logical signals on the output lines B0-B7, in turn, are applied in the input lines A1, A2, A3 and A6 of the chord display elements YO9-Y15, also designated 99-105 in FIG. 3 in a manner similar to that of the scale display. Similarly, outputs from the memory elements are connected to the auxiliary display elements 119-125 which are associated with the main chord display elements YO9-Y15 also designated 99-105 in FIG. 3 in a manner similar to that of the scale display. Similarly, outpus from the memory elements are connected to the auxiliary display elements 119-125 which are associated with the main chord display elements YO9-Y15 for displaying appropriate patterns of sharps and flats according to the particular chords selected. As shown in FIGS. 2 and 3, sharp and flat symbols and multiples thereof are included in three and sometimes four of the areas on the face of each auxiliary display element.

When any one of the chord modification push buttons 14c is depressed, the chord display 12b is modified. The scale and chord selection must be made before the chord modification selection otherwise the circuit inhibits the chord modification selection binary word X11 X10 X9, i.e. the coded three bit word, to the condition O O O or X11 X10 X9. The circuit of FIG. 6 including the diode array and D-type flip-flops 298-300 codes the chord modification selection into the three-bit binary word including the quantities X9, X10, and X11 which are in the form of logical signals present on the lines 42, 41 and 40, respectively, as shown in FIG. 3. The overall operation is summarized by Table 7 wherein the left-hand column indicates the chord modification switches Minor, Suspended, Augmented and Diminished and the three right-hand columns indicate the logical states of the quantities X9, X10 and X11 resulting from activation of the various switches.

Referring now in detail to FIG. 6, a selected one of the push buttons 14c is depressed after a scale and chord selection have been made the lines 290-292 switch to electrical ground accordingly. For example, the switch designated S in FIG. 6 is coded to produce the condition of a logical one on lines 290 and 292 and a logical zero on line 291. The monostable multivibrator 316 triggers on the leading edge, i.e. negative slope, of the signals on lines 290-292 changing state. The multivibrator pulse then clears the flip-flops 298-300 forcing the output lines 40-42 to a low condition, i.e. the quantities X9-X11 each being a logical zero. When the selected push button is then released, the resultant positive-going edges of the signals on lines 290-292 clock the respective flip-flops 298-300 setting the outputs thereof to a high logical state. Until the next scale selection, chord selection, chord modification or clear push button switch is depressed, the previous states or logic levels will exist. The inputs A0-A10 of the read only memory elements designated IC9-IC11 will receive signals having logical levels of the quantities X1-X11, respectively. As determined by the respective truth tables or program tables of these memory elements, the output lines B0-B7 thereof will change state accordingly. As indicated in connection with the scale and chord displays, these tables are included further on in the specification. The logical signals on the output lines B0-B7, in turn, are applied to the input lines A1, A2, A3 and A6 of the chord display elements YO9-Y15, also designated 99-105 in FIG. 3 in a manner similar to that of the scale display. Similarly, outputs from the memory elements are connected to the auxiliary display elements which are associated with the main chord display elements YO9-Y15 for displaying appropriate patterns or sharps and flats according to the selected chord modification.

The foregoing operation is summarized by Tables 8-22 wherein each table is for a different musical key and in each table the first elevel columns indicate the various logical states of the quantities X1-X11 and the remaining seven columns indicate the resulting chord displays provided by the display elements YO9-Y15.

Tables 23 and 24 summarize the operation of the auxiliary display elements 119-125 associated with the main chord display elements in providing flat and sharp indications in response to various logic states of the quantities X1-X11. Similarly, Tables 25 and 26 summarize the operation of the auxiliary display elements which provide double flat and double sharp indications.

Tables 27-37 are truth tables or program tables for the read only memory elements IC1-IC11, respectively, where the A columns indicate the various logical states of the inputs of the particular memory element and the B columns indicate the resulting logical states of the outputs of the memory element.

It is therefore apparent that the present invention accomplishes its intended objects. While a single embodiment of the present invention has been described in detail, this is for the purpose of illustration, not limitation.