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Thread: Windows 2.11/386's VGA screen cutoff, revisited

  1. #1
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    Default Windows 2.11/386's VGA screen cutoff, revisited

    THE SOLUTION FOR ANYONE GOOGLING THIS DOWN THE LINE: It's not a bug, it's a feature™. Windows 2.11/386 runs at 640x450 in VGA mode in order to maintain compatibility with EGA software in windowed mode. This is only actually explained in the documentation for Windows 2.03/386, which also has a 640x480 driver (at the cost of only being able to run EGA software fullscreen.) The fun and thrills of early adoption, eh?

    Quote Originally Posted by original post contents
    So, I've had a weird recurring issue with Windows 2.11/386 inexplicably not using the last 20 or so pixels of the screen (Pictured: DeskPro 386) in VGA mode on all the systems i've tried it on - a COMPAQ DeskPro 386, a IBM PS/2 8580, and a PS/2 55SX. This seems to happen independent of the display connected, and the windowing environment just sort of acts like the dead space isn't there at all in both WIN386 and WIN86: this doesn't happen in 2.11/286's VGA mode, Windows ≥3.0's VGA mode, or in any other programs at all.

    At the time of my last thread I only had my COMPAQ DeskPro 386 and my workbench display to work with limiting what data i could get on the matter, but now I've got more to work with so i figure it's time to pop this case file back open.

    2.11/386 on the PS/2 8580, "dead space" visible. Compare Windows 3.11 on the same machine. (Note: only a shot of WIN86 is available since WIN386 won't run on my later 8580 without a patch that seems to be lost to time)

    Windows 2.11/286 on the PS/2 8555, "dead space" not present. Under 2.11/386, the issue manifests itself.

    The issue seems to not happen under COMPAQ Plasma mode in Windows 2.11/386 on a COMPAQ Portable 386, and under emulated or virtualized environments Windows 2.11/386 makes use of the full 640x480 as it presumably should. (The lines on the display are a plasma panel fault and not connected to the issue)

    Is this just another case of 2.11/386 being buggy, I wonder?
    Last edited by MrArgent; October 27th, 2018 at 02:52 PM.

  2. #2
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    I can't remember if this was asked in the other thread, but are you 100% sure you are using a normal retail version of Windows 2.11/386? Some OEM versions were specific to the OEM's machines and might not work right on a generic or genuine IBM PC.

    I thought 2.11/286 and 2.11/386 used the same DRV drives, although glancing at a copy of 2.11/286 and 2.11/386 the specific driver files are not exactly identical.

    Have you tried copying the 2.11/286 VGA driver over the 2.11/386 VGA driver and installing?

    It does sound like a bug to me. Perhaps some timing issue that prevents the VGA RAM from paging to the right place on certain hardware. I'd speculate it might have to do with the 386 virtualization system, but if it does the same thing with Win86 then that would not be it.

    If you are just looking to get it to work, you might try some other VGA drivers. Glancing at some third party Windows 2.x drivers I see some vendors provided 640*480*16 drivers that may or may not require the vendor's specific hardware.

  3. #3
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    Yup. I've tried a couple of copies from a couple of sources, including a private FTP i'm on that tends to be pretty stringent about making sure things are labelled clearly.

    ...also, I've noticed something interesting.
    Deciding which VGA driver to use with Windows/386:
    --------------------------------------------------------------
    When you are running the Windows/386 setup program, you are given
    two choices if you have a VGA or compatible display adapter. The
    first choice, "VGA, 640x480", will run Windows itself in 640 by
    480 mode. The second choice, "VGA, 640x450", will run Windows in
    640 by 450 mode. If you run Windows in 640 by 480 mode you will
    not be able to run EGA graphics applications in windowed or background
    modes. If you run Windows in 640 by 450 mode you will be able to run EGA
    graphics applications in windowed and background modes. For most users we
    recommend they select the 640 by 450 mode since the loss of 30 lines in
    the horizontal is not very noticeable.
    From documentation included with 2.03/386. The lost space, then, very well could have been by design...though the ability to choose 640x480 or 640x450 seems to have been removed from later iterations in favor of exclusively going for 640x450, seemingly.
    Last edited by MrArgent; October 27th, 2018 at 02:38 PM.

  4. #4
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    Ah, the joys of quick and dirty hacks.

    So the change was made specifically for the 386 mode, but carries over to 8086 mode.

    That also means the desktop is not being "cut off", it just has a smaller desktop. If you run an application maximized, you should not lose the bottom of the window unless the content was hard coded specifically for 640*480.

    If one does not know why it is doing that, it does look like a bug. It was not uncommon to see 640*480*256 drivers fail in a manner like that if an SVGA (512k) video card had faulty RAM in a second bank or mistakenly only had 256K installed.

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