ADF Sections

U34-U41 Toshiba TC524256BZ-10 or NEC D42274V-10 

  This card shares the same video chipset as the 9590 planar. 

J5 Function It looks like a header to supply a video accelerator card that lacks an AVE connector with base video.

Oscillator Functions
  Finally beat them out of Peter 2 Jun 00 
U44 40.0000 MHz  DMA Clock / 2 
U45 44.9000 MHz  Pixelclock 1024x768, 43.5Hz I (8514/A) mode 
U46 28.3220 MHz  VGA / Text mode 
U47 41.5390 MHz  Pixelclock 132-colums mode 
U48 25.1750 MHz  Pixelclock 640 x 480 / 400 modes 

Xfree86 Beginning
Chipset "XGA-1" 
Instance 6 
IObase 0x2160 
COPbase 0xdff00 
MEMbase 0xfd800000 
BIOSabse 0xde000 
DACspeed 45 
Videoram 1024   (Easy, it's either 512 or 1024) 
Clocks 28.322 25.175 41.539 44.9 

XGA Generalities
   The XGA card is an entire graphics subsystem that does not have to rely on a video subsystem on the motherboard of the machine where it is installed. The XGA card is a Bus Master, which means it can do its own processing and memory accesses without having to use the main system processor, providing faster video processing and freeing up the main processor for other tasks. 
   The drivers and the card itself have been optimized to work with the 386 32-bit instruction set. The XGA card comes standard with 512KB of VRAM which provides a maximum resolution of 1024 x 768 with 16 colors. If the memory is upgraded to a full 1MB the maximum increases to 1024 x 768 with 256 colors. 

Possible Erratum
  The XGA Adapter was upgradeable to 640 x 480 with  65,536 colors (!) and 1024 x 768 with 256 colors by means of the PS/2 Video Memory Expansion Option. 

  On IBM PS/2 computers with a 16-bit bus, and XGA, the following error message may appear after  installing the XGA drivers in Microsoft Windows NT: 
       The aperture enabled for the xga device is invalid, please enable the 4MB aperture (preferred) or 1MB aperture using the xga reference disk. 
  This error occurs on 16 MB 16-bit bus PS/2 computers that support a maximum of 16 MB of RAM, such  as the model 9556 or 9557. 

 CAUSE 
  The PS/2 XGA subsystem provides three possible apertures, or windows, to video memory in the physical memory address space of the system. Aperture size options are 64KB, 1MB, and 4MB. The 4MB aperture option is not available on 16-bit computers, such as those based on the 80386 SX processor. The 4MB Aperture is not available if the XGA subsystem is in a 16 bit slot in a 32 bit computer and is only accessible by 32 bit protected mode drivers, such as the drivers used by Microsoft Windows NT. 
  Currently, Microsoft Windows NT only supports XGA with an Aperture of 1MB, or 4MB enabled. On 16-bit IBM PS/2 computers with 16MB RAM, the 1MB meg aperture cannot be enabled. 

  WORKAROUND 
  According to IBM , a possible workaround is to use the standard VGA which does not require this option to work, or decrease the amount of physical RAM below 16MB. 

Video I/O Address
   I/O (Input/Output) address range for the display controller registers. This field also affects the location of the video coprocessor registers. Each adapter you install must have a unique address range.
    <"Instance 6: 2160h - 216Fh">, 1 (2110-211F), 2 (2120-212F), 3 (2130 - 213F), 4 (2140- 214F), 5 (2150-215F), 7 (2170-217F), 0 (2100-210F)

1 MB VRAM Aperture Base Address
   1 MB aperture from the PC into the video memory. If the aperture has been disabled, it is because there wasn't enough available memory address space for system memory and the aperture.
  If the aperture must be re-enabled, and if you cannot use "Set Configuration", then remove the device that is competing for memory such as a system Micro Channel adapter or system memory.
  Removal of system memory may degrade the system performance.  If the aperture has been allocated an address range and it results in a reduction of usable system memory (with Micro Channel memory adapter)  then the aperture can be disabled.
  (Ed. On most systems with >16MB, disable the aperture)
    <"Address at 15 MB (F00000h)" (0F000-0Ffff)>, 14 MB (0E00-0Efff), 13 MB (0D000-0Dfff), 12 MB (0C000-0Cfff), 11 MB (0B000-0Bfff), 10 MB (0A000-0Afff), 9 MB (9000-9ffff), 8 MB (8000-8fff), Disabled

Video Arbitration Level
   Arbitration level the adapter uses  to transfer data.
    <"Arbitration level 13">, 12, 11, 10, 9, 8, 14, 7

Video Fairness
  Select the Bus Arbitration Fairness.  When Bus Arbitration Fairness is set it controls whether the adapter will release control of the bus when it has been using it exclusively.
   <"Fairness On">, Fairness Off

ADPItem 1 ROM Address Range
   This field shows the address of the 8K block of memory that is assigned to the adapter.  Only one XGA or XGA-2 Display Adapter will have the ROM assigned, and any other XGA or XGA-2 Adapter installed will share that address range.