Abstract:
A circuit board socket is provided which is adapted to accept a plug-in single video controller having embedded video memory. The socket allows a circuit board to be easily wired to accommodate different, replaceable embedded memory video controller chips. The socket allows power to be separately supplied from the circuit board via terminals to various portions, including an embedded video memory, of the single-chip video controller. The socket is preferably compliant with AGP and VIP standards.

Description:
BACKGROUND OF THE INVENTION 
     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. 
     DESCRIPTION OF THE RELATED ART 
     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. 
     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. 
     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&#39;s video graphics requirements. 
     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. 
     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&#39;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. 
     SUMMARY OF THE INVENTION 
     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. 
     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&#39;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&#39;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. 
     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. 
     Preferably, the socket and motherboard containing it are compliant with Intel AGP/PCI specifications as well as the VESA VIP specifications for video input. 
     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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates, in block diagram form, a circuit board containing a socket provided in accordance with the invention; 
     FIGS. 2A,  2 B, and  2 C respectively show perspective, top and side views of the socket used on the FIG. 1 circuit board; and, 
     FIG. 3 illustrates the connection of the socket of the invention with VESA VIP compliant modules and add-in boards. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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&#39;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 . 
     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,  2 B and  2 C. 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&#39;s 3D Page Pro, plus associated video memory. 
     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 . 
     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  47   b ,  47   c , and  47   d  provided on board  11 . The S-video and composite video signals are preferably NTSC or PAL compatible. An input/output connector  47   a  is also provided on board  11  for supplying analog and/or digital video input signals  49  to video controller chip  33 . The input/output connectors  47   a  . . .  47   d  are 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 . 
     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,  2 B and  2 C. 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. 
     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. 
     Table I below illustrates a terminal signal configuration for socket  41  which is fully AGP/PCI compliant. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE I 
               
             
             
               
                   
               
               
                 Socket Signal Listing 
               
             
          
           
               
                   
                 Type 
                 Signal Name 
               
               
                   
                   
               
               
                   
                 AGP 
                 +12 V 
               
               
                   
                 AGP 
                 Spare 
               
               
                   
                 AGP 
                 Reserved 
               
               
                   
                 AGP 
                 USB− 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 INTA# 
               
               
                   
                 AGP 
                 RST# 
               
               
                   
                 AGP 
                 GNT# 
               
               
                   
                 AGP 
                 VCC3.3 
               
               
                   
                 AGP 
                 ST1 
               
               
                   
                 AGP 
                 Reserved 
               
               
                   
                 AGP 
                 PIPE# 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 Spare 
               
               
                   
                 AGP 
                 SBA1 
               
               
                   
                 AGP 
                 VCC3.3 
               
               
                   
                 AGP 
                 SBA3 
               
               
                   
                 AGP 
                 Reserved 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 SBA5 
               
               
                   
                 AGP 
                 SBA7 
               
               
                   
                 AGP 
                 Key 
               
               
                   
                 AGP 
                 Key 
               
               
                   
                 AGP 
                 Key 
               
               
                   
                 AGP 
                 Key 
               
               
                   
                 AGP 
                 AD30 
               
               
                   
                 AGP 
                 AD28 
               
               
                   
                 AGP 
                 VCC3.3 
               
               
                   
                 AGP 
                 AD26 
               
               
                   
                 AGP 
                 AD24 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 Reserved 
               
               
                   
                 AGP 
                 C/BE3# 
               
               
                   
                 RGB 
                 Red 
               
               
                   
                 RGB 
                 Green or Green + Sync 
               
               
                   
                 RGB 
                 Blue 
               
               
                   
                 RGB 
                 Ground - Red 
               
               
                   
                 RGB 
                 Ground - Green 
               
               
                   
                 RGB 
                 Ground - Blue 
               
               
                   
                 RGB 
                 Ground - Sync 
               
               
                   
                 RGB 
                 V. Sync or not used 
               
               
                   
                 RGB 
                 H. Sync or not used 
               
               
                   
                 RGB 
                 DDC data (SDA) 
               
               
                   
                 VIP 
                 VID0 
               
               
                   
                 VIP 
                 VID1 
               
               
                   
                 RGB 
                 Data Clock 
               
               
                   
                 Power 
                 AVDD0 
               
               
                   
                 Power 
                 AVDD1 
               
               
                   
                 Power 
                 VDDQ0 
               
               
                   
                 Power 
                 GNDL0 
               
               
                   
                 Power 
                 GNDL4 
               
               
                   
                 Power 
                 GNDL8 
               
               
                   
                 Power 
                 VDDDQ0 
               
               
                   
                 Power 
                 VDDDQ1 
               
               
                   
                 Power 
                 VDDDQ2 
               
               
                   
                 Power 
                 VDDDQ2 
               
               
                   
                 Power 
                 VDDDQ3 
               
               
                   
                 Power 
                 VDDDQ4 
               
               
                   
                 Power 
                 VDDDQ5 
               
               
                   
                 Power 
                 VDDDQ6 
               
               
                   
                 Power 
                 VDDDQ7 
               
               
                   
                 Power 
                 VDDDQ8 
               
               
                   
                 Power 
                 VDDDQ9 
               
               
                   
                 Power 
                 VDDDQ10 
               
               
                   
                 Power 
                 VDDDQ11 
               
               
                   
                 Power 
                 VDDDQ12 
               
               
                   
                 Power 
                 VDDDQ13 
               
               
                   
                 Power 
                 VDDDQ14 
               
               
                   
                 Power 
                 VDDDQ15 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 AGP 
                 OVRCNT# 
               
               
                   
                 AGP 
                 5.0V 
               
               
                   
                 AGP 
                 5.0V 
               
               
                   
                 AGP 
                 USB+ 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 INTB# 
               
               
                   
                 AGP 
                 CLK 
               
               
                   
                 AGP 
                 REQ# 
               
               
                   
                 AGP 
                 VCC3.3 
               
               
                   
                 AGP 
                 ST0 
               
               
                   
                 AGP 
                 ST2 
               
               
                   
                 AGP 
                 RBF# 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 Spare 
               
               
                   
                 AGP 
                 SBA0 
               
               
                   
                 AGP 
                 VCC3.3 
               
               
                   
                 AGP 
                 SBA2 
               
               
                   
                 AGP 
                 SB_STB 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 SBA4 
               
               
                   
                 AGP 
                 SBA6 
               
               
                   
                 AGP 
                 Key 
               
               
                   
                 AGP 
                 Key 
               
               
                   
                 AGP 
                 Key 
               
               
                   
                 AGP 
                 Key 
               
               
                   
                 AGP 
                 AD31 
               
               
                   
                 AGP 
                 AD29 
               
               
                   
                 AGP 
                 VCC3.3 
               
               
                   
                 AGP 
                 AD27 
               
               
                   
                 AGP 
                 AD25 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 AD_STB1 
               
               
                   
                 AGP 
                 AD23 
               
               
                   
                 Comp 
                 Composite Signal 
               
               
                   
                 Comp 
                 Composite Ground 
               
               
                   
                 S-Video 
                 Ground Luminance 
               
               
                   
                 S-Video 
                 Ground - Chrominance 
               
               
                   
                 S-Video 
                 Y - Luminance 
               
               
                   
                 S-Video 
                 C - Chrominance 
               
               
                   
                 VIP 
                 VIPOCLK 
               
               
                   
                 VIP 
                 HAD0 
               
               
                   
                 VIP 
                 HAD1 
               
               
                   
                 VIP 
                 HCTL 
               
               
                   
                 VIP 
                 VID2 
               
               
                   
                 VIP 
                 VID3 
               
               
                   
                 VIP 
                 PIXCLK 
               
               
                   
                 VIP 
                 VRST# 
               
               
                   
                 VIP 
                 VIRQ# 
               
               
                   
                 Power 
                 VDDQ1 
               
               
                   
                 Power 
                 GNDL1 
               
               
                   
                 Power 
                 GNDL5 
               
               
                   
                 Power 
                 GNDL9 
               
               
                   
                 Power 
                 VDDDQ16 
               
               
                   
                 Power 
                 VDDDQ17 
               
               
                   
                 Power 
                 VDDDQ18 
               
               
                   
                 Power 
                 VDDDQ18 
               
               
                   
                 Power 
                 VDDDQ19 
               
               
                   
                 Power 
                 VDDDQ20 
               
               
                   
                 Power 
                 VDDDQ21 
               
               
                   
                 Power 
                 VDDDQ22 
               
               
                   
                 Power 
                 VDDDQ23 
               
               
                   
                 Power 
                 VDDDQ24 
               
               
                   
                 Power 
                 VDDDQ25 
               
               
                   
                 Power 
                 VDDDQ26 
               
               
                   
                 Power 
                 VDDDQ27 
               
               
                   
                 Power 
                 VDDDQ28 
               
               
                   
                 Power 
                 VDDDQ29 
               
               
                   
                 Power 
                 VDDDQ30 
               
               
                   
                 Power 
                 VDDDQ31 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 AGP 
                 Vddq3.3 
               
               
                   
                 AGP 
                 AD22 
               
               
                   
                 AGP 
                 AD20 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 AD18 
               
               
                   
                 AGP 
                 AD16 
               
               
                   
                 AGP 
                 Vddq3.3 
               
               
                   
                 AGP 
                 FRAME# 
               
               
                   
                 AGP 
                 Reserved 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 Reserved 
               
               
                   
                 AGP 
                 VCC3.3 
               
               
                   
                 AGP 
                 TRDY# 
               
               
                   
                 AGP 
                 STOP# 
               
               
                   
                 AGP 
                 PME# 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 PAR 
               
               
                   
                 AGP 
                 AD16 
               
               
                   
                 AGP 
                 Vddq3.3 
               
               
                   
                 AGP 
                 AD13 
               
               
                   
                 AGP 
                 AD11 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 AD9 
               
               
                   
                 AGP 
                 C/BE0# 
               
               
                   
                 AGP 
                 Vddq3.3 
               
               
                   
                 AGP 
                 Reserved 
               
               
                   
                 AGP 
                 AD6 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 AD4 
               
               
                   
                 AGP 
                 AD2 
               
               
                   
                 AGP 
                 Vddq3.3 
               
               
                   
                 AGP 
                 AD0 
               
               
                   
                 AGP 
                 Reserved 
               
               
                   
                 Power 
                 VDDL0 
               
               
                   
                 Power 
                 VDDL1 
               
               
                   
                 Power 
                 VDDL2 
               
               
                   
                 Power 
                 VDDL3 
               
               
                   
                 Power 
                 VDDL4 
               
               
                   
                 Power 
                 VDDL5 
               
               
                   
                 Power 
                 VDDL6 
               
               
                   
                 Power 
                 VDDL7 
               
               
                   
                 Power 
                 VDDD0 
               
               
                   
                 Power 
                 VD 0 
               
               
                   
                 VIP 
                 V1.4 
               
               
                   
                 VIP 
                 VIDV 
               
               
                   
                 Power 
                 VDDD2 
               
               
                   
                 Power 
                 VDDD3 
               
               
                   
                 Power 
                 GNDD2 
               
               
                   
                 Power 
                 VDDQ2 
               
               
                   
                 Power 
                 GNDL2 
               
               
                   
                 Power 
                 GNDL6 
               
               
                   
                 Power 
                 PVDD 
               
               
                   
                 Power 
                 GNDDQ0 
               
               
                   
                 Power 
                 GNDDQ1 
               
               
                   
                 Power 
                 GNDDQ2 
               
               
                   
                 Power 
                 GNDDQ3 
               
               
                   
                 Power 
                 GNDDQ4 
               
               
                   
                 Power 
                 GNDDQ5 
               
               
                   
                 Power 
                 GNDDQ6 
               
               
                   
                 Power 
                 GNDDQ7 
               
               
                   
                 Power 
                 GNDDQ8 
               
               
                   
                 Power 
                 GNDDQ9 
               
               
                   
                 Power 
                 GNDDQ10 
               
               
                   
                 Power 
                 GNDDQ11 
               
               
                   
                 Power 
                 GNDDQ12 
               
               
                   
                 Power 
                 GNDDQ13 
               
               
                   
                 Power 
                 GNDDQ14 
               
               
                   
                 Power 
                 GNDDQ15 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 AGP 
                 Vddq3.3 
               
               
                   
                 AGP 
                 AD21 
               
               
                   
                 AGP 
                 AD19 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 AD17 
               
               
                   
                 AGP 
                 C/BE2# 
               
               
                   
                 AGP 
                 Vddq3.3 
               
               
                   
                 AGP 
                 IRDY# 
               
               
                   
                 AGP 
                 Reserved 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 Reserved 
               
               
                   
                 AGP 
                 VCC3.3 
               
               
                   
                 AGP 
                 DEVSEL# 
               
               
                   
                 AGP 
                 Vddq3.3 
               
               
                   
                 AGP 
                 PERR# 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 SERR# 
               
               
                   
                 AGP 
                 C/BE1# 
               
               
                   
                 AGP 
                 Vddq3.3 
               
               
                   
                 AGP 
                 AD14 
               
               
                   
                 AGP 
                 AD12 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 AD10 
               
               
                   
                 AGP 
                 AD6 
               
               
                   
                 AGP 
                 Vddq3.3 
               
               
                   
                 AGP 
                 AD_STB0 
               
               
                   
                 AGP 
                 AD7 
               
               
                   
                 AGP 
                 GND 
               
               
                   
                 AGP 
                 AD5 
               
               
                   
                 AGP 
                 AD3 
               
               
                   
                 AGP 
                 Vddq3.3 
               
               
                   
                 AGP 
                 AD1 
               
               
                   
                 AGP 
                 Reserved 
               
               
                   
                 Power 
                 GNDL0 
               
               
                   
                 Power 
                 GNDL1 
               
               
                   
                 Power 
                 GNDL2 
               
               
                   
                 Power 
                 GNDL3 
               
               
                   
                 Power 
                 GNDL4 
               
               
                   
                 Power 
                 GNDL5 
               
               
                   
                 Power 
                 GNDL6 
               
               
                   
                 Power 
                 GNDL7 
               
               
                   
                 Power 
                 GNDL8 
               
               
                   
                 Power 
                 GNDL9 
               
               
                   
                 VIP 
                 VID6 
               
               
                   
                 VIP 
                 VID7 
               
               
                   
                 Power 
                 GNDD0 
               
               
                   
                 Power 
                 GNDD1 
               
               
                   
                 Power 
                 GNDD3 
               
               
                   
                 Power 
                 VDDQ3 
               
               
                   
                 Power 
                 GNDL3 
               
               
                   
                 Power 
                 GNDL7 
               
               
                   
                 Power 
                 PGND 
               
               
                   
                 Power 
                 GNDDQ16 
               
               
                   
                 Power 
                 GNDDQ17 
               
               
                   
                 Power 
                 GNDDQ18 
               
               
                   
                 Power 
                 GNDDQ18 
               
               
                   
                 Power 
                 GNDDQ19 
               
               
                   
                 Power 
                 GNDDQ20 
               
               
                   
                 Power 
                 GNDDQ21 
               
               
                   
                 Power 
                 GNDDQ22 
               
               
                   
                 Power 
                 GNDDQ23 
               
               
                   
                 Power 
                 GNDDQ24 
               
               
                   
                 Power 
                 GNDDQ25 
               
               
                   
                 Power 
                 GNDDQ26 
               
               
                   
                 Power 
                 GNDDQ27 
               
               
                   
                 Power 
                 GNDDQ28 
               
               
                   
                 Power 
                 GNDDQ29 
               
               
                   
                 Power 
                 GNDDQ30 
               
               
                   
                 Power 
                 GNDDQ31 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                 Socket X 
                 Reserved 
               
               
                   
                   
               
             
          
         
       
     
     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. 
     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. 
     
       
         
               
               
               
             
           
               
                   
                 TABLE II 
               
               
                   
                   
               
               
                   
                 Pin 
                 Signal Name 
               
               
                   
                   
               
             
             
               
                   
                 RGB 
                 Red 
               
               
                   
                 RGB 
                 Green or Green + Sync 
               
               
                   
                 RGB 
                 Blue 
               
               
                   
                 RGB 
                 Ground - Red 
               
               
                   
                 RGB 
                 Ground - Green 
               
               
                   
                 RGB 
                 Ground - Blue 
               
               
                   
                 RGB 
                 Ground - Sync 
               
               
                   
                 RGB 
                 H. Sync or not used 
               
               
                   
                 RGB 
                 V. Sync or not used 
               
               
                   
                 Composite 
                 Composite Signal 
               
               
                   
                 Composite 
                 Composite Ground 
               
               
                   
                 S-Video 
                 Ground - Luminence 
               
               
                   
                 S-Video 
                 Ground - Chrominance 
               
               
                   
                 S-Video 
                 Luminence 
               
               
                   
                 S-Video 
                 Chrominence 
               
               
                   
                 DDC 
                 Data Clock 
               
               
                   
                 DDC 
                 DDC data (SDA) 
               
               
                   
                   
               
             
          
         
       
     
     Also shown in Table I are pin designations for the VIP video input signals. The VIP signals are also shown in Table III below. 
     
       
         
               
               
               
               
             
           
               
                   
                 TABLE III 
               
               
                   
                   
               
               
                   
                 Signal 
                 Description 
                 Location 
               
               
                   
                   
               
             
             
               
                   
                 VIPOCLK 
                 VIP Host Clock (25-33 MHz) 
                 Host Port 
               
               
                   
                 HAD[1:0] 
                 Host Address/Data Bus 
                 Host Port 
               
               
                   
                 HCTL 
                 Host Control 
                 Host Port 
               
               
                   
                 VID[7:0] 
                 ITU-R-656 Video Data 
                 Video Port 
               
               
                   
                 PIXCLK 
                 ITU-R-656 Pixel Clock 
                 Video Port 
               
               
                   
                 VRST# 
                 VIP Module Reset 
                 System Signal 
               
               
                   
                 VIRQ# 
                 Interrupt Request 
                 System Signal 
               
               
                   
                   
               
             
          
         
       
     
     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. 
     
       
         
               
               
               
             
           
               
                   
                 TABLE IV 
               
               
                   
                   
               
               
                   
                 Signal 
                 Description 
               
               
                   
                   
               
             
             
               
                   
                 VDDL[8:1] 
                 Digital Logic Power 
               
               
                   
                 VDDD[4:1] 
                 DRAM Power 
               
               
                   
                 VDDDQ[32:1] 
                 DRAM I/O Power 
               
               
                   
                 AVDD[2:1] 
                 DAC Power 
               
               
                   
                 VDDQ[4:1] 
                 AGP Digital I/O Power 
               
               
                   
                 PVDD 
                 Pixel Clock Synthesizer 
               
               
                   
                 PGND 
                 Pixel Clock Synthesizer Ground 
               
               
                   
                 GNDL[10:1] 
                 Digital Logic Ground 
               
               
                   
                 GNDD[1:4] 
                 DRAM Ground 
               
               
                   
                 GNDDQ[32:1] 
                 DRAM I/O Ground 
               
               
                   
                   
               
             
          
         
       
     
     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.  2 B. 
     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. 
     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.