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Thread: Compaq Portable + Compaq EGA

  1. #1

    Default Compaq Portable + Compaq EGA

    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...

  2. #2
    Join Date
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    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.

  3. #3

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    Quote Originally Posted by modem7 View Post
    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.
    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.

  4. #4

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    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 by resman; February 3rd, 2019 at 02:03 PM.

  5. #5

    Default

    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
    My Vintage computer/blog site
    Searching for a keyboard for a WYSEpc WY-1100.

  6. #6

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    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

  7. #7
    Join Date
    Jan 2012
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    Connecticut, USA
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    2,155

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    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

  8. #8

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    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!

  9. #9
    Join Date
    Jan 2012
    Location
    Connecticut, USA
    Posts
    2,155

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    Where did you acquire this card?
    I installed Win 3.0 on my portable II, just need a mouse now.

  10. #10

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    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.

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