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Thread: NEC Powermate SX stuck at 8Mhz with a 386SX-16

  1. #1

    Default NEC Powermate SX stuck at 8Mhz with a 386SX-16

    I've come into possession of a NEC Powermate SX (not the Plus version) which is described as a "8/16Mhz" system. It has a 16Mhz 386SX on a little expansion card that plugs into the motherboard, along with a socket for a 387.

    However I cannot get the chip to rate past 8Mhz. All the documentation I've been able to find does not suggest that the CPU's speed is physically set via switches or jumpers. Stason labels one jumper as "ATCLK clock mode select", but neither jumper position makes any difference on the CPU's speed. A technical document on ps-2.kev009 relabels that jumper as "sync/async mode", which isn't a much better explanation.

    I do have the setup/diagnostic disk for the system, but it's limited to date/time, drive settings, and setting memory amounts. Nothing to do with the CPU at all.

    I posted a similar question about the original NEC Powermate APC regarding a 286 at 8Mhz that seemed to be able to go to 10Mhz, but never got a reply on that one. It appears the NEC systems were not very popular I suppose, though I'm still hoping someone has some insight into this baffling problem.

  2. #2

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    What are you using to 'rate' the CPU's speed?
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  3. #3

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    I'm using CheckIt. It's never failed me before.

  4. #4
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    A detailed photo of the mainboard might help...

    Some boards also used key combos like Ctrl+<something> to change the speed.

  5. #5

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    Usually it's Ctrl + and Ctrl - to toggle the speed where the + and - are the ones on the numerical keypad.

    Have you looked at the CMOS settings? Some boards have a setting there to set the bootup board speed.
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  6. #6

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    I hadn't thought of using the Ctrl keys to manage the CPU speed. I'll try that tonight and post a picture of the motherboard as well.

    That would explain the "10Mhz" LED on the original NEC Powermate though. Correct key toggle = LED on. I am properly chagrined.

  7. #7

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    I have a PowerMate SX/16. To switch to turbo mode, press Ctrl-Alt-[numeric keypad plus key]. To go back to non-turbo mode, press Ctrl-Alt-[numeric keypad minus key].

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    Quote Originally Posted by raifield View Post
    I do have the setup/diagnostic disk for the system, but it's limited to date/time, drive settings, and setting memory amounts. Nothing to do with the CPU at all.
    Quick question - is it an actual NEC program, or just a generic AT setup program like GSETUP?
    Does the Powermate 386SX not have a built in setup program - Ctrl+Alt+S or Ctrl+Alt+Ins? (I don't have a Powermate 386, so no idea, just throwing out some things to try)
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  9. #9

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    Quote Originally Posted by SpidersWeb View Post
    Quick question - is it an actual NEC program, or just a generic AT setup program like GSETUP?
    Does the Powermate 386SX not have a built in setup program - Ctrl+Alt+S or Ctrl+Alt+Ins? (I don't have a Powermate 386, so no idea, just throwing out some things to try)
    The documentation I found states that it does via Ctrl+Alt+S, but pressing that does nothing either during boot or after it. The setup program is NEC's diagnostic/setup software for the Powermate SX, not a generic program.

    Quote Originally Posted by vwestlife View Post
    I have a PowerMate SX/16. To switch to turbo mode, press Ctrl-Alt-[numeric keypad plus key]. To go back to non-turbo mode, press Ctrl-Alt-[numeric keypad minus key].
    Like an idiot, I was hammering Ctrl+Alt+Plus, figuring that would trigger the higher speed. Plus key, increase, it made sense to me. That didn't work, so out of frustration I hit the minus key instead.

    That works. Ctrl+Alt+Minus toggles the speed between 8 and 16 on the Powermate SX and I'll update the post I made last month about the Powermate 1, as that key combination will likely switch the 286 from 8 to 10.

    Thanks! Why they didn't make the Plus key do anything, we'll never know...

  10. #10
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    Quote Originally Posted by raifield View Post
    Thanks! Why they didn't make the Plus key do anything, we'll never know...
    I've actually found quite a few machines where minus was speed a toggle.
    Which is odd because back then I always remember + and - being up and down.
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