Forum Rules and Etiquette

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486 motherboard manual needed, Mitac PH4500AU

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    486 motherboard manual needed, Mitac PH4500AU

    Quite a while back i found a 486 board on ebay for cheap and I got it for a hot-rod 486 build. Well I've finally gotten around to it, and I've been stumped by the 30 some odd jumpers on this board. Normally the TH99 database is my friend ( however, even it has failed me. It is pretty much as close to perfect in a 486 as I can expect to find. The bios is ~GLORIOUS~ for a 486 board. Its almost a late model pentium bios on a 486! However I want to disable the onboard IDE (scsi master race), enable the 586 parts of the cpu in the picture, (its set to amd dx4), install 1mb L2 cache... and so forth.


    The model on the sticker is PH4500AU, searching has come up with jack squat on this board. I've even looked at EVERY 486 image on for similar boards. The closest boards in an amptron 9500 (or close to that)

    I'm hoping someone here will recognize this board and can either help with a link to the manual / jumper settings, or at least point me in the correct direction if this is a re-branded board of some sort. I fired off an email to Mitac & Tyan and neither has replied.

    Thanks in advance!
    It is a mistake to think you can solve any major problems just with potatoes.

    I looked everywhere and it doesn't look like there is a copy of that manual online. The closest was a Mitac PB5400 manual on, but that looks like it is for a later pentium based model.


      without the manual, I make this educated guess. the 3 jumpers below the cpu are for voltage, the 4 jumper block might be for bus speed, the clusterfauck or jumpers on top, is for cpu type selection, the smaller clusterfauck next to the cache is probably for cache size, type, and various other little features, maybe even ties into the cpu selection jumpers. I would trial and error it, but be careful. and don't mess with anything next to the voltage regulator thingy * I honestly don't know what they are called, only what they do *
      Nothing beats the roar of a 36yr old drive coming to life after a decade in storagg



        I found this on :

        The jumpers settings for the PH4500AM mainboard

        A BIOS update for the PH4500AU mainboard (PH4500AU.BIN)

        There is also this page but the FTP server is down...

        Hope it helps...


          well it already has the 1.06 bios, and it looks to be the latest. Which is good. Sadly the AM version is a pci-vlb-isa board and the jumpers don't match at all.
          It is a mistake to think you can solve any major problems just with potatoes.


            Well, there is:

            Which has some jumpers for different boards.


              yea the 4500AM is a VLB/PCI/ISA board, its probably close, but none of the jumpers match up. I'm just guessing the jumpers near the VRM control voltage and the ones near the main oscillator control frequency/multi. These don't match between the AM datasheet and the AU version.
              It is a mistake to think you can solve any major problems just with potatoes.