Certain IBM VGA Observations

[Great Hierophant]

I had the opportunity to run some imformal tests of the IBM PS/2 Display Adapter. This is an 8-bit full-length VGA card IBM released as an upgrade for its 8086 based PS/2 Model 30, which used the MCGA adapter. While it was not officially supported in the PC family, it could be used in the 5150, 5155, 5160, 5162 or 5170 without (too much) difficulty. I tried some games on it:

Icon - Quest for the Ring: Works Properly (using 9x16 fonts)
Icon Demo - Shows unreduced text cells
7 Spirits of Ra - Game screen stretched, leaving several rows undisplayed.
8088 Corruption - Works only if not using a real CGA card is selected
Space Quest III - CGA graphics option displays cyan/magenta/white instead of cyan/red/white as on real CGA.
Commander Keen 6 - Smooth scrolling works with SVGA compatibility unchecked.

I also have IBM's EGA card lying around, but do not have a digital TTL monitor to test it with. I would love to know how these the tests would result on that device.

 

[Trixter]

This is all par for the course, really. You were testing CGA compatibility with a VGA card, which is not 100% CGA compatible (some registers have different VGA-specific meanings), and your results are 100% predictable. Everything you saw was exactly how a VGA card reacts to some custom CGA stuff.

8088 Corruption works when you say it's not a pure CGA because I specifically assumed people would try it on VGA, so when you say "N" I load the 8x8 font, switch to 200-scanline mode, and set 40 columns. The exact code I used is this:

  {set up the video mode}
  if realCGA
    then asm
      mov  ax,01h {set 40x25}
      int  10h
      mov  dx,3d8h
      mov  al,c_videosignal_enable {blinking not included, so blinking is off}
      out  dx,al
    end else asm {if VGA, do something completely different}
      MOV AX,1200h {set up 200 scan lines}
      MOV BL,30h
      INT 10h
      MOV AX,0001h {set up normal 40x25 text mode}
      INT 10h
      MOV AX,1102h {load 80x50 vga character set}
      MOV BL,00
      INT 10h
      mov ax,1003h {disable blink on ega/vga}
      mov bl,0
      int 10h
    end;

BTW I've almost finished editing the video taken of me explaining how I did 8088 Corruption; the video, and full source and more movies, will be available on the webpage in a few days. I'll try to remember to come back here and pimp it

 

[evildragon]

I had the opportunity to run some imformal tests of the IBM PS/2 Display Adapter. This is an 8-bit full-length VGA card IBM released as an upgrade for its 8086 based PS/2 Model 30, which used the MCGA adapter. While it was not officially supported in the PC family, it could be used in the 5150, 5155, 5160, 5162 or 5170 without (too much) difficulty. I tried some games on it:

Icon - Quest for the Ring: Works Properly (using 9x16 fonts)
Icon Demo - Shows unreduced text cells
7 Spirits of Ra - Game screen stretched, leaving several rows undisplayed.
8088 Corruption - Works only if not using a real CGA card is selected
Space Quest III - CGA graphics option displays cyan/magenta/white instead of cyan/red/white as on real CGA.
Commander Keen 6 - Smooth scrolling works with SVGA compatibility unchecked.

I also have IBM's EGA card lying around, but do not have a digital TTL monitor to test it with. I would love to know how these the tests would result on that device.

you sure it was the Model 30 that was 8086? cause I got a Model 25, and as far as I know, that was the ONLY 8086 system that existed.. I made a VGA card for it, myself though.. i desolded the HD-15 connector, and wired it right to the video connector that the internal monitor uses..

 

[the xt guy]

The model 30 was 8086 as well (I've got one). There was also a later model 30 with a 286, usually referred to as the 30-286.

The model 30 is more of a conventional style in a small desktop style case with a seperate monitor, rather than having the monitor built on top of the CPU unit like the 25.

 

[evildragon]

The model 30 was 8086 as well (I've got one). There was also a later model 30 with a 286, usually referred to as the 30-286.

The model 30 is more of a conventional style in a small desktop style case with a seperate monitor, rather than having the monitor built on top of the CPU unit like the 25.

oh, that's right! isn't it the one with the same motherboard as the model 25? i remember hearing about those...

 

[IBMMuseum]

oh, that's right! isn't it the one with the same motherboard as the model 25? i remember hearing about those...

No, the 8086 version of the Model 30 was a different planar than the 8086 Model 25. For the 286 version of each there was the same planar. But it so happens there were *two* different variations of the 286 planar.

 

[evildragon]

No, the 8086 version of the Model 30 was a different planar than the 8086 Model 25. For the 286 version of each there was the same planar. But it so happens there were *two* different variations of the 286 planar.

huh, i heard it was different...

i have two model 25's however, each with a different motherboard.. one uses a plastic GPU, the other uses a ceramic one (the older machine i use now instead).. other changes are things in totally different locations..

 

[IBMMuseum]

huh, i heard it was different...

i have two model 25's however, each with a different motherboard.. one uses a plastic GPU, the other uses a ceramic one (the older machine i use now instead).. other changes are things in totally different locations..

There are also two variations of the 8086 Model 30 planar. However both versions won´t fit in a Model 25 case (nor will other stock IBM planars go back into a Model 30 8086 case). When getting to the 286 level IBM changed the case style for the Model 30, so that the Model 25 style planars could fit in it (the Model 25 even had a 386SX level planar that wasn´t put in a Model 30 case).