XGA Display Adapter/A

Extended Graphics Array - "Expressway"

@8FDB.ADF IBM XGA Display Adapter/A
C8FDB.ADF Init file for @8FDB.ADF

190-182 IBM PS/2 XGA Display Adapter/A

XGAUTIL.exe For use by P70/P75 display adapter.
XGAOPT.exe XGA/XGA2 Display Adapter Options Disk (details HERE)
xga212.exe XGA/XGA-2 Win3.1/ACAD/DQMS/DOS AI

XGA206 Windows 95/98 XGA-2 Display Driver by Unal Z
XGA208 Windows 9x and NT XGA/XGA-2 Display Drivers by UZnal

XGAKIT.ZIP IBM XGA Graphics routines. C and ASM Source. C Demo program.
VESA XGA Extensions Standard (VXE 1.0) (Thanks to Michal Necasek)

xgademo.zip XGA Demonstration v1.2 (easy install version by "Retro Erik")
   (created by Mike O'Hara of Analyst International Corporation, 1992)

PS2 XGA Adapter Interface Technical Reference Sep 90
IBM VGA XGA Technical Reference Manual May 92
XGA: A New Graphics Standard by Jake Richter
The PC Graphics Handbook
Programming the XGA POS Registers

MSM514262 256Kx4 ZIP
MT42C4256Z-8 Datasheet
TN-42-01 Upgrading from 1 Meg to 2 Meg VRAMs
TN-42-02 Designing with MT42C4256/8128 VRAM
TN-42-03 Regular, Real-Time, Split Read Transfers
TN-42-04 Bank Interleaving w/ EDO VRAMs
TN-42-05 Four-Column vs Eight-Column Block Write

XGA Common Information

XGA Adapter
Adapter ROM
Win98SE Support for 64K colors
Linux Modelines
Invalid Aperture on NT
XGA Origins and Codename ("Expressway")
ADF Sections

XGA Adapter /A FRU P/N 75X5886, P/N 75X5887, FCC ID ANO75X5887 [P] [P]

J1 HDD15 video connector
J5 Pads for 20-pin header
U7,8,9 TDK ZJY-2P
U10 37F0842 RAMDAC
U11 TC110GC9AG / TC110GC9AF
U2032Kx8 SRAM (sprite/attribute buffer)
U27 37F9567 video ROM
U34-41 Video RAM
U44 40.0000 MHz osc
U45 44.9000 MHz osc
U46 28.3220 MHz osc
U47 41.5390 MHz osc
U48 25.1750 MHz osc

U34-41 Toshiba TC524256BZ-10 or NEC D42274V-10 Note: -80 VRAM works fine!
TDK ZJY-2P 2 Line Common Mode Choke datasheet
U10 37F0842 Serializer Palette DAC (INMOS IMS G190)
U11 TC110GC9AG XGA Display Controller (INMOS IMS G200)
U20 OKI M51257AL-12 or compatible 32Kx8 SRAM (sprite/attribute buffer)

J5 Solder pads for header to supply a base video. This function is performed by the Base Video Extension (BVE) right below the outline.

Oscillator Functions (from Peter)

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

Different XGA Display Controllers

TC110GC9AG / 1888676 9108
37F0842 19107 RAMDAC

TC110GC9AF / 74F5160 9215 "BAKE"
37F0842 19323 RAMDAC

Model 90 Planar
TC110GC9AF / 74F5160 9214 "BAKE"
37F0842 19210 RAMDAC

I postulate that a new XGA Display Controller, TC110GC9AF / 74F5160 came out in early 92. Note the Part Number for the original XGA Display Controller, IBM P/N, 1888676... Sure reminds me of the Hursley designed Image Adapter/A...

Adapter ROM

1x 27C256-15 32Kx8 CMOS EPROM (U27)
(SGS Thompson M27C256B-15, AMD AM27C256-155, ST M27C56B-15FI, or compatible)

37F9576 XGA BIOS Ver 2.00 20-07-90
37F9576 XGA BIOS Ver ?.?? 15/03/91

XGA Block Diagram

Flow of control and addressing signals, and the data flows from the external interfaces (PS/2 interface and Base Video Extension) through the components to the display.

XGA Adapter/A (standalone)
POST in Adapter PROM
Fits in Base Video Extension (BVE) slot, providing Base Video to AVE (ex. Model 95)

XGA on planar
POST in the system ROM
Provides Base Video to Auxiliary Video Extension (AVE) (ex. Model 90)

XGA CPU Requirements
The XGA Adapter/ A can be used in all Micro Channel machines with a 80386, 80386SX or i486 processor. 80286 (and earlier) processors lack 32 bit registers and segment registers.

XGA Slot Width
The XGA Adapter/ A performs faster in a 32-bit slot, but it will still run in a 16-bit slot. However, for 32-bit operations, it will require two bus cycles instead of one, and memory addressability will be limited to 16MB.

Both planar and Adapter/A perform faster with 1 MB because the data path into the video display buffer memory is 32-bits wide. At 512 KB, the data path width is only 16-bits wide.

W98SE Supports 64K Colors
Yes, folks, I have been to the mountaintop, and it is good. W98SE has built-in support for 640x480 at 16/256/64K colors (finally!) and 1,024x768 at 16/256 colors.

Linux Modelines (Xfree86 Beginning)

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

XGA Generalities

The XGA card is a Base Video card - it does not need a planar video subsystem. It is a Bus Master, able to do its own processing and memory accesses without using the system processor, providing faster video processing and freeing up the main CPU for other tasks.

The drivers and the card have been optimized to work with the 386 32-bit instruction set. The max resolution with 512KB of VRAM is 1024 x 768 with 16 colors, with 1MB the max is 1024 x 768 with 256 colors. When upgraded with the 512K (PS/2 Video Memory Expansion Option), the XGA adds 640 x 480 with 65,536 colors in Direct Color Mode.

Invalid Aperture on NT

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.


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.


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.

Installation Instructions (source)

Installation of the XGA card is much like any other Micro Channel adapter.

First, simply place the card in a Micro Channel expansion slot. A 32-bit slot is preferred, due to the speed advantage. There is however one slot the XGA card will not fit, and that is the slot with the AVE. The XGA card does have an extension that looks much like the 8514/A extension; however, upon closer inspection you will see the extension on this card is positioned differently. The positioning of the XGA extension tab will prevent it from being inserted into the slot with the auxiliary video extension.

The XGA card only occupies 8KB of memory between 640KB and 1MB. Since the XGA card is a Bus Master, it can occupy any 8KB in the "C" or "D" range. To see which part of memory is being used by the XGA card, choose the menu option "Display Memory Map" from the Reference Diskette. Another great feature of the XGA card is that you can have up to six XGA cards installed in one machine (five if the system has XGA already on the motherboard, like the Model 90). To take advantage of multiple adapters, software must be specifically written to do so.

If you have an XGA card in a system that has VGA on the system board and a display attached just to the XGA card, the XGA card will function in VGA and high resolution modes. Now, if you have the same setup as before but a display is attached to the motherboard VGA port and another to the XGA card, all VGA (and lower modes) will be displayed on the display attached to the motherboard port. The XGA card will only be used when high resolution is required. You will not get an echo of a VGA image onto the display attached to the XGA port as you would using the 8514/A.

Once the card is installed, the appropriate device driver must be installed before the high resolution can be accessed. There are two device driver diskettes that come with the XGA card. The first diskette contains all of the device drivers for DOS, Microsoft Windows 3.0, Microsoft Windows 286 2.1, and AutoCAD Release 10. The second diskette contains support for OS/2 1.2 (OS/2 1.3 ships with an XGA driver).

XGA Origins and Codename ("Expressway")

Hardware Products Developed at Hursley "Expressway" - XGA Adapter

Spacemont (a portmanteau of Space Mountain at Disney World being the highest point in Florida) was a project between Hursley and Boca to develop a follow-on to the VGA PC graphics adapter. However, it fell foul of compatibility and cost issues and was canned after 6 months in favor of an extension of the VGA (called rather unexcitingly the XGA).

The processor and pixel engine were the starting point for Image Adapter, and the pixel engine was the starting point for the drawing engine of XGA. In collaboration with IBM Research, Yorktown, the simulator created to test the Spacemont VLSI before manufacture, General B, was also used effectively on Image Adapter development.

1987 PS/2 Image Adapter/A Combined video display and (optional) printer adapter supporting virtually all IBM PC monitors at the time, and a number of 3rd party image printers. Used CMOS-2 chip developed at Hursley (Cotswold II).

AdapterId 8FDB XGA Display Adapter/A

Video I/O Address
   I/O address range for display controller registers. This also affects the location of video coprocessor registers. Each XGA adapter 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 PC into video memory. If aperture has been disabled, it is because there wasn't enough available memory address space for system memory and the aperture.

  Removal of system memory may degrade system performance.  If 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
  (Bus Arbitration) controls if adapter releases control of bus after using it exclusively.
   <"Fairness On">, Fairness Off

ADPItem 1 ROM Address Range
   8K block of memory assigned to 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.

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Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

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