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Compaq Portable + Compaq EGA

resman

resman

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I found a Compaq branded EGA card with the intent of upgrading my Compaq Portable. The Compaq EGA card has the internal header to plug the CRT into. However, it has two sets of switches that must configure the EGA for the special frequencies/modes of the Portable. I have looked high and low looking for any documentation on the Compaq EGA card to no avail. I did try plugging in the card to see if it would just work, but no dice. It did work when placed into my Deskpro with the Compaq monochrome monitor at CGA resolutions. Oddly, setting the motherboard switches to "Compaq Monitor" got it to come up in CGA resolution. So I know the card is pretty much functional.

I'm hoping someone out there has an upgraded Portable with the Compaq EGA card and can post the switch settings before I go crazy. Thanks in advance,

Dave...
 
To support EGA, if the motherboard's BIOS is at revision B, it will need to be upgraded to revision C. See the 'Portable and Portable Plus - Warning' link at [here].

Then, according to [here], with the BIOS at revision C, the motherboard switch settings are the same as for an IBM XT, with a caveat. The caveat is that if the motherboard has both a SW1 and SW2 switch block, the settings are made on SW2.
So for EGA,
* Motherboard (at BIOS revision C) with one switch block: Switches 5 and 6 on SW1 both set to ON.
* Motherboard (at BIOS revision C) with two switch blocks: Switches 5 and 6 on SW2 both set to ON.
 
modem7 said:
To support EGA, if the motherboard's BIOS is at revision B, it will need to be upgraded to revision C. See the 'Portable and Portable Plus - Warning' link at [here].

Then, according to [here], with the BIOS at revision C, the motherboard switch settings are the same as for an IBM XT, with a caveat. The caveat is that if the motherboard has both a SW1 and SW2 switch block, the settings are made on SW2.
So for EGA,
* Motherboard (at BIOS revision C) with one switch block: Switches 5 and 6 on SW1 both set to ON.
* Motherboard (at BIOS revision C) with two switch blocks: Switches 5 and 6 on SW2 both set to ON.
Click to expand...

Yes, I have the Rev C with support for expansion ROMs and the switches are set for "80x25 RGB or EGA" (actually says EGA - this is a Portable from 1986). I need to get the switch setting for the EGA card proper. I'm hoping there is something that says "setting for Portable CRT". One switch block is on the top of the card and the other on the back with access through the backplate.
 
Apparently the manual for the Compaq EGA (also referred to as the ECGB - Enhanced Color Graphics Board in some Compaq documentation) is unobtanium. So, in lieu of the facts, guess...

TL;DR summary: methodically go through switch settings to see what works and what doesn't.

Finally found a setting that boots up in a lores (200 line) 80x25 text mode. Running a TurboC++ example program that uses their BGI library to test graphics modes, I found which switch setting uses video timings for the 640x350 hires mode that work with the dual mode CRT controller in the Portable. Now, I wanted to use the hires text mode for the cleaner looking fonts and the ability to use 43 line mode. I couldn't find a combination of switch settings that allowed booting into hires 80x25 text mode. Using "MODE ,43" failed with an unsupported mode failure. Luckily, I use Compaq's version of DOS 5 and have the manual. The Compaq version of MODE.EXE has special options for the Portable and external dual mode monitors. When combined with the Compaq VDU (their CGA) or the Compaq ECGB (their EGA), you can switch to the hires characters. For me, the magic incantation was "MODE SELECT=EGA COLOR" and the text mode switched to the hires character set. Oddly, it still won't switch into 43 line mode using MODE.EXE, but some programs that support that mode can switch to it, the TurboC++ IDE for instance. By adding "MODE SELECT=EGA COLOR" to AUTOEXEC.BAT, the Portable now boots into hires 80x25 text mode.

For future documentation, here are the currently working switch settings and results (80x43 in TurboC++ IDE):

IMG_0780.jpg

IMG_0781.jpg

IMG_0786.jpg

I would still like it to boot into hires text mode without having to force a MODE command and be able to set 43 line mode in DOS. But, I'm pretty happy now that I have an EGA equipped Portable with 286 accelerator and XTIDE+DOM. Sweet.
 
Last edited:
That's pretty cool, I never knew this was an option, I am going to have to go on the hunt for one of the Compaq EGA cards now ;-)
 
Finally got around to writing the image display routine for the EGA. Since the portable converts the colors to monochrome, I mapped that to a greyscale ramp to display monochrome images. With the fine doth pitch and a little dithering at 640x350 make for a nice hires display. I always have my retro computers display selfies in the highest resolution/highest colors they can:
IMG_0795.jpg
 
You lucky dog! That is pretty damn neat... I wont bother looking, as Im sure it will be cost prohibitive. MAybe someone will make a new card down the road. That image looks amazing btw! If you said it was VGA id believe you
 
Thanks - I really couldn't believe my luck when I stumbled upon this EGA card. Windows 3.0 looks really nice, too. I can play solitaire and actually read the cards!
 
ePay, of all places. And a very reasonable price. A retro-computing miracle. I use a Genius serial mouse to keep things simple for Windows 3.0.
 
As a last follow-up, I decided to treat the switches on the back of the card just like the IBM EGA, which is well documented. Of course Compaq was very diligent in replicating IBMs feature set, so it was no surprise that the IBM monitor switch setting on the IBM card were replicated on the Compaq EGA card. My Portable now boots into the hi-res text mode, as opposed to the 640x200 mode it was set to. No need to play around with MODE.EXE to fix it. The switch setting on the back of the card look like this, for anyone searching in the future:
IMG_0877.jpg
 
Moogle! said:
Was this EGA card a fully Compaq designed product? If not, it may have a non-Compaq branded cousin listed somewhere on TH99.
Click to expand...
It's a Compaq PCB and BIOS using a C&T chipset. What makes it so unique is the internal header for connecting to the Portable's CRT and the timings to work with its dual frequency operation.
 
COMPAQ EGA board SW1 (1 2 3 4) as primary display adapter; these configure default video mode at boot time

color 80x25 (640x350) - off on on off
color 80x25 (640x200) - on on on off
color 80x25 (640x200) - off off off on
color 40x25 (320x200) - on off off on
mono 80x25 (720x350) - off off on off
mono 80x25 (720x350) - on off on off

The two 640x200 color modes differ in that the second one also supports RGBI color monitors, in addition to the COMPAQ color monitor, EGA monitor, or COMPAQ Dual-Mode monitors the first supports. I'm not entirely sure what that means in technical terms.

The two mono modes differ only in which mode is allowable for a secondary color board (80x25 for the first, 40x25 for the second). both modes only support the COMPAQ Dual-Mode monitor.

COMPAQ EGA board SW2 (1 2 3 4 5 6); these configure the attached monitor.

External monitor: SW2 - 1 & 2
COMPAQ Color Monitor or EGA - off off
COMPAQ Dual-Mode monitor - off on
RGBI color monitor - on off
no external monitor - on on

Internal monitor: SW2 - 3
COMPAQ Dual-Mode monitor - off
no internal monitor - on

Reserved: SW2 - 4, 5 & 6 (always on off on)

COMPAQ EGA board JP1; external monitor type
COMPAQ Color monitor or EGA - 1&2
COMPAQ Dual-Mode or RGBI - 2&3

JP3 (always 1&2)
 
Thanks for all that! Do you have the manual for the Compaq EGA (and where were you three months ago ;-) )?
 
Hi, can you post the pinout of the cable of the internal monitor of the portable?
I have an EGA wonder and I am trying to do the same thing. Also can you post a photo of the internal connector of the Compaq EGA to internal monitor?
 
ghosthuntergr said:
Hi, can you post the pinout of the cable of the internal monitor of the portable?
I have an EGA wonder and I am trying to do the same thing. Also can you post a photo of the internal connector of the Compaq EGA to internal monitor?
Click to expand...

For reference, the pinout of the VDU->CRT connector on my system is:

----------------
| 1 2 3 4 || 5 |
| 6 7 8 9 || 10|
----------------

1 - Red - VSync - Negative Pulse ~150us All Modes, 50Hz MDA, 60Hz CGA
2 - Black - CGA Mode Active? - High in CGA mode, low in MDA mode. My CRT appears to multi-sync and ignore this.
3 - Orange - Analog video data - ~3V max observed
4 - Brown - Hsync - Positive Pulse ~5us All Modes, 15.7kHz CGA, 18.5kHz MDA
5 - Grounding Strap
6,7,8,9 - White - Video Ground
10 - NC

See: http://www.vcfed.org/forum/showthread.php?50640-EGA-on-built-in-CRT-of-Compaq-Portable-1
 
ghosthuntergr said:
Hi, can you post the pinout of the cable of the internal monitor of the portable?
I have an EGA wonder and I am trying to do the same thing. Also can you post a photo of the internal connector of the Compaq EGA to internal monitor?
Click to expand...

http://www.vcfed.org/forum/showthread.php?50640-EGA-on-built-in-CRT-of-Compaq-Portable-1

For reference, the pinout of the VDU->CRT connector on my system is:

----------------
| 1 2 3 4 || 5 |
| 6 7 8 9 || 10|
----------------

1 - Red - VSync - Negative Pulse ~150us All Modes, 50Hz MDA, 60Hz CGA
2 - Black - CGA Mode Active? - High in CGA mode, low in MDA mode. My CRT appears to multi-sync and ignore this.
3 - Orange - Analog video data - ~3V max observed
4 - Brown - Hsync - Positive Pulse ~5us All Modes, 15.7kHz CGA, 18.5kHz MDA
5 - Grounding Strap
6,7,8,9 - White - Video Ground
10 - NC
 
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