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Thread: Compaq Deskpro 386/25

  1. #1

    Default Compaq Deskpro 386/25

    I was always an IBM PC/XT/AT guy and never really touched a compaq. Now, I have this cool Deskpro 386/25 with 3MB of memory. What is the skinny on adding memory to these boxes? Can you use third party memory cards like in the AT?

    I need to get more memory in this to play Doom and speed up windows 3.11.

    Thanks for any advice/info.

    Kurt
    -------------------------------------------------------

    My Vintage Computer Collection

  2. #2
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    You should be able to use standard ISA memory cards, although if this system has a proprietary memory upgrade slot, any memory added that way will be faster. I don't happen to have my Compaq reference book handy but it would probably say whether a special memory board was available on this model.

  3. #3

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    This is what I have listed:
    Code:
    Memory Boards 	        Assembly        Spare Part
    1 MB System Memory      000752/001103   113224-001
    
    4 MB System Memory      000765          113222-001
    
    4 MB Memory Module      000758/000993   113226-001
                            001166-001/002 	   ''
    
    1 MB Memory Module 	000762/000981   113225-001
                            001076             ''
                            001151-001         ''
                            001256/001259      ''
    Kingston probably made an aftermarket card too.

    Are the chips socketed? You may be able to upgrade to a higher density.

  4. #4
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    If I'm reading the Compaq Service QuickRef right, I think the Deskpro 386/25 had no memory on the motherboard at all -- instead it had a special memory expansion slot that could take one of two cards: the 1MB system memory board, or the 4MB system memory board. Both boards could accept up to 3 additional memory modules, and the modules were available in 1MB and 4MB sizes.

    For the 1MB system memory board, the following module combinations are documented:
    _ _ _ 1MB
    1 _ _ 2MB
    1 1 _ 3MB
    1 1 1 4MB
    4 _ _ 5MB
    1 4 _ 6MB
    1 4 1 7MB
    4 4 _ 9MB
    4 4 1 10MB
    4 4 4 13MB

    For the 4MB system memory board, the following combinations are documented:
    _ _ _ 4MB
    1 _ _ 5MB
    1 1 _ 6MB
    1 1 1 7MB
    4 _ _ 8MB
    4 1 _ 9MB
    4 1 1 10MB
    4 4 _ 12MB
    4 4 1 13MB
    4 4 4 16MB

    "documented" in this context means "NOTE: ADD MEMORY MODULES AS SHOWN TO OBTAIN DESIRED MEMORY CONFIGURATION". I don't know if other combinations would work but this is what the Service QuickRef shows.

    If you have 3MB that means a 1MB system memory board with 2 1MB modules installed (assuming no memory via an ISA slot). So you have room for 1 more module. If you get a 1MB module you can simply put it in the last position. If you get a 4MB module you may need to put it in the middle position, and move the 1MB module that was previously there to the last position.

    Note that if you go all the way to 16MB using a 4MB system memory board with 3 4MB add-on modules you won't be able to add memory via an ISA slot because the ISA slot can only address up to 16MB (i.e. the maximum possible memory on this system is 16MB).

    The ISA bus on this computer can run at 8MHz (if the CPU is clocked at 24MHz) or 8.33MHz (if the CPU is clocked at 25MHz). If you have ISA cards that won't run at 8.33MHz you may need to drop the CPU speed down to 24MHz using jumper E14.
    Last edited by kgober; March 12th, 2018 at 02:24 PM.

  5. #5

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    This information was invaluable! Thank you so much!

    On a lark, I google the product IDs of the modules that you listed. I found a company with 4MB refurbished modules for $10 each! I bought 3 of them and populated the memory board. I now have 13 MB of RAM! Doom runs great!
    Installing windows and MS office pro right now. It came with an ethernet card, so I will next play with TCP/IP and get a browser installed.

    Thanks again.

    Kurt
    -------------------------------------------------------

    My Vintage Computer Collection

  6. #6
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    Good stuff.
    Thomas Byers (DRI)- "You'll have a million people using the A> [MS-DOS prompt] forever. You'll have five million using [nongraphic] menu systems such as Topview, Concurrent PC-DOS, Desq, and those types. But there'll be 50 to 100 million using the iconic-based interfaces."

  7. #7

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    Quote Originally Posted by Kurthamm View Post
    I found a company with 4MB refurbished modules for $10 each!
    Hey, Kurt. I just un-mothballed a Deskpro 386/25 this week. It has the 1MB 32-bit board with a single 4MB module (current 5MB total).
    Googled a bit, but couldn't find anyone the expansion modules. Can you share where you found yours?

    Thanks?
    “The Bex religious impulse does have its collective side. As in, collect everything and hold on to it whether you remember where it came from or not.”
    —Alberto Fossa, Privateer 2

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