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Thread: Questions about WDM286 -WDM20 motherboard

  1. #21
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    Quote Originally Posted by Stone View Post
    The manual states that 4 MB is the maximum amount memory.
    The manual says that will go up to 16 megs of ram, i don't know why but if install more than a 1 meg i start to get all kind of parity errors tried several sets of 1 megabyte modules. Also tried installing just 2 modules to get 2 meg but was unable to have stop having the parity errors any way i try.

  2. #22

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    Quote Originally Posted by soviet9922 View Post
    The manual says that will go up to 16 megs of ram...
    Not the manual I have. It's the printed manual that came with my 286.
    If you're looking for DS/DD or DS/HD 3" or 5" floppy disks, PM me. I've got some new, used, and factory over-labeled disks for sale.

    There is a crack in everything. That's how the light gets in. -- Leonard Cohen
    ☞ Time flies like an arrow; fruit flies like a banana.

  3. #23
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    Ok end up assembling the ibm using this motherboard and works great!.
    Also soldered to the onboard enable and monochrome jumpers a dpdt switch to the back so i can enable hercules graphics from the onboard. So i could enable disable the onboard video some software and games don't like to have the cga and mda adapter present at the same time. Its a shame that when in EGA mode the onboard video conflicts to the CGA card.
    It could be cool to disable the CGA ibm card using some kind of switch.


  4. #24

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    Quote Originally Posted by soviet9922 View Post
    Its a shame that when in EGA mode the onboard video conflicts to the CGA card.
    It could be cool to disable the CGA ibm card using some kind of switch.
    Why do you need the IBM CGA card when the on board display adapter can be used for EGA, CGA or MDA?

    Additionally, the on board EGA display adapter can be configured as either the primary or secondary adapter along with a separate CGA adapter. Do you have the DIPs and jumpers set correctly?
    If you're looking for DS/DD or DS/HD 3" or 5" floppy disks, PM me. I've got some new, used, and factory over-labeled disks for sale.

    There is a crack in everything. That's how the light gets in. -- Leonard Cohen
    ☞ Time flies like an arrow; fruit flies like a banana.

  5. #25
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    Quote Originally Posted by Stone View Post
    Why do you need the IBM CGA card when the on board display adapter can be used for EGA, CGA or MDA?
    Probably because he wants to use the composite signal from the berg connector on the CGA card to drive the 5155s internal display

    Quote Originally Posted by Stone View Post
    Additionally, the on board EGA display adapter can be configured as either the primary or secondary adapter along with a separate CGA adapter. Do you have the DIPs and jumpers set correctly?
    I can't find jumpers to configure on-board video for primary or secondary. I don't think it would get along with the CGA card anyway. The only way I can get video from my CGA card is to set the on-board as MONO and DISABLE.

  6. #26

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    Quote Originally Posted by ibmapc View Post
    I can't find jumpers to configure on-board video for primary or secondary.
    The jumper is:

    W18

    and switch SW1-1, 2, 3, 4, and 5.
    If you're looking for DS/DD or DS/HD 3" or 5" floppy disks, PM me. I've got some new, used, and factory over-labeled disks for sale.

    There is a crack in everything. That's how the light gets in. -- Leonard Cohen
    ☞ Time flies like an arrow; fruit flies like a banana.

  7. #27
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    Quote Originally Posted by Stone View Post
    The jumper is:

    W18

    and switch SW1-1, 2, 3, 4, and 5.
    TH99 says W18 is for Color or Mono and SW1 is for the different modes of those.
    Capture.JPG

    Did you scan the pertinent pages in your manual for us?
    Last edited by ibmapc; November 1st, 2017 at 06:12 PM.

  8. #28

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    Keep in mind that with a separate CGA card installed the on board video port can only be used with a mono monitor, regardless of which display is designated as primary.
    If you're looking for DS/DD or DS/HD 3" or 5" floppy disks, PM me. I've got some new, used, and factory over-labeled disks for sale.

    There is a crack in everything. That's how the light gets in. -- Leonard Cohen
    ☞ Time flies like an arrow; fruit flies like a banana.

  9. #29
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    Quote Originally Posted by soviet9922 View Post
    i have now another bizarre issue, the motherboard came with 4 triple height 30 pinn simm's they are 256 k each....
    Now if i replace them for some bigger 1 meg simms x4 sets (i have tried multiple memory sets that run fine in others machines), everthing seems ok i can run 20 times checkit 3 and pass all memory tests run games and programs ok using dos 6.22 but if i try to run drdos 6 installer i got a memory parity error instantly.
    Im not sure if my ram is bad incompatilbe or theres something different on drdos 6 ?.
    Check your BIOS version. If it is older than Ver. 1.15 you might consider updating it. This will get you the EVEN part and This will get you the ODD part. You will then need to program a pair of 27256 EPROMs with those files and replace the ones on your motherboard. I did that with mine last night and it solved a couple of issues I was having. My original bios version was 1.08 and I found the RAM mapping was wonky when using 4 x 1 MB SIMMs to get 4 MB total. I was getting parity errors when I used an Intel Above Board card to add additional extended memory. After upgrading the bios to Ver 1.15 that problem went away. So this may solve your DRDOS problem as well.

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