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Thread: IBM PC AT Memory - what should I try to get

  1. #1

    Default IBM PC AT Memory - what should I try to get

    Hi Everyone,

    I do have some DRAM IC's from a six pack board that I pulled already - I guess all of them are 64Kx1:
    mcm4164 qty 33
    mcm6665 qty 21

    I put a request in to see if anyone had an IBM memory adapter they wanted to sell, but no one responded so I'm probably going to open that up to looking for any AT compatible memory board.

    I have 512K on the MB and 128K on an IBM card.

    Q#1 - what type of memory expansion am I looking for? Is all of it going to start at 0x100000, or will any of it fill in between 640K and 1M? Is that supported? Is that beneficial? Is there a card that does this? Is this a stupid question!!!!

    Q#2 - if I am just looking for memory to go at 1MB and above, what type of cards should I be looking for that are AT compatible? I'd ideally like 1M or 2M of additional memory over the 640K. Can that be done in a single card? Which ones would work?


  2. #2


    What are you looking to do with the additional memory?
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  3. #3


    Possibly run a newer DOS (MS-DOS 6.22) without having less memory available, load SMARTDRV, the compiler I want put on it also uses extended/expanded memory.

  4. #4
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    May 2009
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    The card you should look for would be an EMS 4.0 card with SIMMs that also supports extended memory. Most of these would provide up to 8 MB of RAM (using currently very cheap 1 MB SIMMs) which could be split* between expanded and extended according to needs. I had one from AST but the other major card makers had equally good models. IBM cards are low in capacity and don't support the full range of standards.

    * As a general rule, one would have some extended memory for the HMA so DOS can load high. Only 64kB is needed for that but most cards allocated in 512 kB chunks. A minimal sized 512 kB chunk of expanded would be enough for most application software that used expanded memory. Combined, that accounts for 1 MB of additional memory. Unless running Windows 3 or OS/2 (which need lots of extended) or DesqView or Windows 2** (needing lots of expanded), the remaining memory will be stuck as a disk cache and should be allocated to whatever is faster with the cache software selected.

    ** If running multiple larger applications


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