Socket for receiving a single-chip video controller and circuit board containing the same

[0002] The present invention relates to a structure for mounting a video controller on a processor circuit board, sometimes called a “motherboard” for use in computers, such as personal computers and network workstations. In particular, the invention is directed to a socket adapted to receive a plug-in single-chip video controller, and to a circuit board and computer system containing the socket.

[0003] Currently video controllers for use in small computers, such as personal computers and network computers, are connected to a processor motherboard in one of two ways. One is by hard wiring a plurality of video controller integrated circuits (“chips”) and associated video memory directly onto a computer motherboard, and the other is by plugging in a card containing the video controller circuitry and associated memory into a card socket provided on the motherboard.

[0004] Currently many, if not most, video controller chip sets directly wired to the motherboard, or video controller cards which plug into a socket on the motherboard, comply with the Intel AGP/PCI interface standard called the Accelerated Graphics Port Interface Specification (Version 1.0, published by Intel, Jul. 31, 1996). This is a high speed specification for a video bus designed to improve video data throughput through a computer system and permits access of the video controller to main system memory for certain video operations.

[0005] When a video controller chip set is directly wired onto the motherboard, the motherboard manufacturer chooses the chip set based on its own design criteria which may or may not reflect the needs of the ultimate computer user. Although this provides a relatively low cost video controller implementation, the video controller design is fixed and inflexible. Accordingly, if a user wishes to change, e.g. upgrade, the video controller, it is impossible to do so without changing the motherboard or adding a separate plug-in video controller board to an available PCI bus socket. Replacing the motherboard is both costly and time consuming, and is typically only done by a trained professional. Adding a new video controller board is also costly and, additionally, the PCI bus structure is relatively slow considering today's video graphics requirements.

[0006] In addition, a wired-in video controller chip set also requires additional land patterns on the motherboard to accommodate the several chips which implement the video controller as well as the associated video memory, and to provide additional memory land areas for possible expansion of the video memory.

[0007] The plug-in video controller board has advantages over the wired-in chip sets, since the user can easily replace one video controller board, which includes the video chip set and associated video memory, with another. While this allows for ease of modification of the video controller circuitry without requiring replacement of the motherboard, the plug-in video controller board itself is expensive and further it occupies one of the computer system's accessory sockets which may limit or hamper the ability of the user to plug in other desired circuit cards. Indeed, for those motherboards which accept a plug-in video controller card which is AGP/PCI compliant, a special socket is required just for the video controller board.

[0008] The present invention is designed to remedy problems associated with both the wired-in video controller chip set and the plug-in video controller boards. It provides a socket for a motherboard which is adapted to receive a single chip integrated circuit video controller which has embedded video memory and which provides all of the video controller functions currently supplied by existing video controller chip sets or plug-in video card controllers and associated video memory. Preferably the socket and its associated plug-in video controller chip are AGP/PCI compliant.

[0009] Providing a socket for receiving a single-chip plug-in video controller on the motherboard allows an OEM computer system manufacturer and/or vendor to easily adapt the computer system to the video requirements of a user by simply choosing the plug-in chip which best fits the user's requirements. The invention also provides a reduced system cost compared to add-in card video controller implementations and provides for a simplified assembly and testing of a computer system. Likewise, a vendor or user can easily replace one plug-in video controller chip with another for upgrading or if the user's video requirements otherwise change. This also allows for easy and relatively inexpensive upgradability of the video controller without requiring replacement of a motherboard or a whole card of expensive components. Furthermore, using a single chip video controller permits the computer system to obtain a higher speed video performance with reduced power consumption because of the embedded memory within the video controller chip.

[0010] Accordingly, the invention provides a plug-in single chip video controller socket for use on a motherboard and a motherboard and computer system containing the socket. The socket is wired on the motherboard and is electrically connected with the other board components which make up a computer system, including a microprocessor, main memory circuits, input/output ports etc. The socket has receiving terminals for the pins of the video controller chip and electrical solder terminals for connecting the pins of the video controller chip with the other circuits on the motherboard. The socket also provides connections between the video controller chip and video input and output terminals also provided on the motherboard. A computer system circuit board is thus provided which allows for an easy choice of video controllers to be used with the computer system, while at the same time freeing up board real estate normally reserved for the video chip sets and associated video memory and/or for a socket for a plug-in video controller card.

[0011] Preferably, the socket and motherboard containing it are compliant with Intel AGP/PCI specifications as well as the VESA VIP specifications for video input.

[0012] These and other advantages and features of the invention will be more readily understood from the following detailed description of the invention, which is provided in connection with the accompanying drawings.

[0013] FIG. 1 illustrates, in block diagram form, a circuit board containing a socket provided in accordance with the invention;

[0014] FIGS. 2A, 2B, and 2C respectively show perspective, top and side views of the socket used on the FIG. 1 circuit board; and,

[0015] FIG. 3 illustrates the connection of the socket of the invention with VESA VIP compliant modules and add-in boards.

[0016] Referring to FIG. 1, a circuit board 11 is shown having computer system components mounted thereon which are depicted in block diagram format. The computer system is designed to be compliant with the Accelerated Graphics Port Specification, revision 1.0 by Intel Corporation, published Jul. 31, 1996, which is incorporated herein by reference. The computer system includes a system main memory 13, a portion 15 of an accelerated graphic port (AGP) bus, an accelerated graphics port compliant chip set 17 (such as Intel 440LX or equivalent), a bus 19 interconnecting the chip set 17 with a microprocessor 21 which, may for example, be an Intel Pentium II microprocessor, another portion 23 of the accelerated graphics bus, and a conventional PCI bus 27 which interconnects the AGP compliant chip'set with input/output ports 31 for the other devices, e.g. key board, hard drive, floppy drive, CD-ROM drive, mouse, etc. through additional bus structures 25 and 29.

[0017] The AGP compliant chip set 17 is connected via the portion 23 of the AGP bus with a single-chip video controller 33 which is mounted to board 11 by a socket 41, shown in greater detail in FIGS. 2A, 2B and 2C. The single chip video controller 33 performs all the functions currently performed by an AGP/PCI compliant video chip set or plug-in controller board in accordance with the AGP/PCI interface specification described above. For example, the video controller chip 33 performs all the functions of, and has connection pins which correspond to, the connection terminals of the commercially available Number Nine Visual Technology plug-in video controller board known as the Revolution 3D, the Matrox plug-in video controller board known as the Millennium II or the Diamond Stealth II S220 or the Matrox Mystique 200 boards. Alternatively, video controller chip 33 performs all the functions of, and has connection pins which correspond to the connection terminals of the commercially available chip sets known as Cirrus Logics CL-6D5465A.C.P. or ATI's 3D Page Pro, plus associated video memory.

[0018] The video processor 33 includes video memory 37 and a video accelerator 39. Video memory 37 and accelerator 39 are all integrated on a single plug-in IC chip 33 which connects to the remaining circuitry on board 11 through socket 41.

[0019] The chip 33 transmits and receives, through socket 41, all of the AGP/PCI signals normally transmitted and received by a AGP/PCI compliant plug-in video controller card, as required by the AGP/PCI specification. Video controller chip 33 also produces display signals in the form of an RGB signal 42, an S-video signal 43 and a composite video signal 45 which are supplied to respective pins of connectors 47b, 47c, and 47dprovided on board 11. The S-video and composite video signals are preferably NTSC or PAL compatible. An input/output connector 47ais also provided on board 11 for supplying analog and/or digital video input signals 49 to video controller chip 33. The input/output connectors 47a. . . 47dare designed to connect various external display monitors and/or television sets to the board 11 computer system and to receive input from an analog or digital video source which is supplied by a bus 49 as an input to the video controller chip 33.

[0020] As noted, the video controller chip 33 is mounted to the circuit board 11 via a socket 41 which is illustrated in greater detail in FIGS. 2A, 2B and 2C. Socket 41 is a zero insertion force (ZIF) socket and is similar in design and operation to a so-called “socket 7”, which is currently used to mount plug-in microprocessor chips, such as the Intel Pentium, to a circuit board. Socket 41 has a chip release mechanism, such as the illustrated manually manipulated lever 63, for allowing the quick and easy release of video controller chip 33 from socket 41. Although a manually manipulated lever 63 is illustrated in the drawings, any other mechanism which permits easy release of controller chip 33 from socket 41 can be used. Socket 41 also includes a terminal pattern 65 which provides a keying structure which insures that only a plug-in chip video controller 33, which has the correct complementary pin key structure and which is properly arranged on socket 41 can be inserted therein.

[0021] Socket 41 includes receiving terminals 43 for receiving the pins of the plug-in video controller chip 33 and corresponding solder tail terminals 47 which are wired onto circuit board 11. The terminals 43 and 47 are sufficient in number to carry all the signals necessary for a plug-in video controller chip 33 which is compliant with the AGP/PCI interface specification.

[0022] Table I below illustrates a terminal signal configuration for socket 41 which is fully AGP/PCI compliant.

[0023] As noted, the control chip 33 includes embedded video memory 37. Accordingly, it is normally not necessary for the video accelerator circuitry 39 of the video controller chip 33 to access system main memory when performing video display operations; however, the AGP/PCI specification does recognize that the video controller may access and use such memory for certain operations. Since the video controller circuitry, including video memory, is entirely incorporated into a single video controller chip 33, the video circuitry can easily be replaced, as needed, by simply being removed from the associated socket 41. Video memory can be easily increased by replacement of the video controller chip 33 with one having more embedded memory.

[0024] It should be noted that video input 49 to chip 33 is not part of the AGP/PCI interface specification. However, video controller chip 33 and associated socket 41 have terminals for receiving a video input. This video input may be an analog or digital video input, but is preferably a video input which is compliant with proposed VESA standard for the video interface port (VIP). The VESA VIP specification version 1P, draft 3, of Oct. 2, 1997, is the current working draft and this document in incorporated herein by reference. The VIP video input signals are in digital format. As Table 1 illustrates above, socket 41, according to the invention, provides receiving terminals identified as Type AGP which are signals to and from the computer system which are currently required of an AGP compliant video board. In addition, Table 1 shows pin designations for the RGB, composite video, and S-video output signals. For ease of identifying and showing these terminals, Table II below shows the terminals for the RGB, S-video and Composite signals.

[0025] Also shown in Table I are pin designations for the VIP video input signals. The VIP signals are also shown in Table III below.

[0026] The power supply terminals of socket 41 include terminals necessary for supplying power to the various circuit portions of video controller chip 33, including for digital logic, pixel clock synthesizer, embedded DRAM memory, DRAM (input/output) I/O logic, digital to analog converter, AGP I/O digital logic etc. These power supply terminals are more easily seen from TABLE IV below.

[0027] As also illustrated in Table I, various terminals of socket 41 are reserved for future features which may be incorporated into subsequent generations of the video controller chip 33. In total, socket 41 includes 292 receiving terminals 43 and corresponding solder tail terminals 47 and is configured with 73 receiving terminals 43 (and corresponding solder tail terminal 47) on each of the four sides of its generally square configuration as shown in FIG. 2B.

[0028] FIG. 3 illustrates the connection of the plug-in video controller chip socket 41 with a VESA VIP compliant video input module 5 or the terminals of an add-in VIP compliant board 59 which can be used in conjunction with circuit board 11. The necessary signal paths to allow the socket 41 to be used with a VIP module or add-in board are illustrated. The socket 41 terminal signal designations which provide for this connection are contained in Tables I and III above.

[0029] While the foregoing describes a preferred embodiment of the invention, many modifications can be made without departing from its spirit or scope. Accordingly, the invention is not limited by the foregoing description, but is only limited by the scope of the claims which are appended hereto.