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Thread: Quick Question Overdrive CPU

  1. #1
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    Default Quick Question Overdrive CPU

    Just found a socket 3 PCI motherboard this past week that had an Overdrive chip in it (dx20dpr66). When I turn on the computer it's registering as a 66mhz dx2, is this normal or ahould I be changing the jumper settings? I was under the impression that the pr66 designation meant it was the equivalent of a 66mhz Pentium which would make it somewhere around 100mhz I believe, similar to the dx4-100.
    Last edited by RadRacer203; October 25th, 2019 at 05:17 AM.

  2. #2
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    Well, Intel never used the PR ratings in that way during the 486 period. The overdrive chip you have IS a 486DX2-66 with the 487 pinout, which is slightly different from the oem 486DX pinout.
    --
    Thus spake Tandy Xenix System III version 3.2: "Bughlt: Sckmud Shut her down Scotty, she's sucking mud again!"

  3. #3
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    Oh, then that's weird because it's being used as a standalone here. I guess I'll be pulling it then, and swapping in a normal 486 so I can use the Overdrive in something with a soldered SX and a 487 socket.

  4. #4
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    I believe "odpr" means it's a "replacement" overdrive processor (which means it replaces the original CPU) rather than an "upgrade" overdrive processor that goes into a dedicated overdrive upgrade socket.

    so a DX2ODPR66 is a DX2-66 that is designed to replace a DX-33 or SX-33.

    see also: http://www.cpu-world.com/info/80486/80486upgrade.html

  5. #5
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    The 487 was often noticeably cheaper than the matching 486DX so a lot of budget systems had a single socket which could fit either a 487 or 486 and a bunch of jumpers to select which CPU is installed.

  6. #6
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    Ah, ok. That makes sense. Kind of odd they would use this one though, the motherboard it's paired with is a late one with pci. Seems like it was marketed as a cheap upgrade for earlier boards or stuff that didn't have a regular 486 socket

  7. #7

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    Keep in mind that any 80487 contains a full-blown 80486; the 80487 will disable an existing 80486 (hence the different pinout) and take over completely. There is no point in having both processors installed in the same system, except for bragging rights and higher energy consumption.

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