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First post, by b_rros

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Hi, so I spend the afternoon building a 486 using various things I had around
Right now, it have a DX2 66MHz processor, 8 MB RAM, my AWE32 with the DB50XG for DOOM, and my old video card, this one was from my first PC, as the motherboard.

Everything is working just fine, except that I can't restart the PC, if I change some setting in the BIOS after I choose save + exit the computer freezes, if I press ctrl + alt + del after turning on the PC the same thing happens, the PC just freezes, the reset button works just fine.

I already swaped the hard drive, memory, hard disk, cmos battery, I can't think of anything else.

The only thing I'm doing that I don't usually do is that I have the AWE32 in a VLB slot (I have all 3 VLB slots populated). I can't use the AWE in a ISA slot because it doesn't fit, it thouches the cooler of the processor.

Any thoughts of what my be causing the lockups?

Thanks

And some photos 😀

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Reply 2 of 11, by Anonymous Coward

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Have you tuned the BIOS settings?

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 3 of 11, by dacow

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I'm with feipoa, have you tried removing all but the bare essentials and seeing if you can exit the BIOS without freezing? Unplug all devices including CD-ROM, floppies etc and just see if you have any issues with just the VGA card?

I noticed it looks like you have a IDE-CF card in there, maybe the first thing is to unplug that to see if it's causing the issue?

Reply 4 of 11, by b_rros

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No BIOS changes, I'm using defaults, I tried removing the card and changing the CPU to a 33 MHz one and the same thing happened 🙁
The CF-IDE adapter is there but it's not connected to anything, great eyes 😀

One of the times it gave me an error on startup saying there was a problem with the hard disk controller, does this VLB controllers go bad often? This will be my second one in a few months. All I have now are ISA ones, I will try with one of that and see how that goes...

DOSBox is so much easier than this! 😜

Reply 5 of 11, by dacow

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b_rros wrote:

All I have now are ISA ones, I will try with one of that and see how that goes...

DOSBox is so much easier than this! 😜

I've never heard of VLB ide controllers going bad, but fixing hardware issues is the fun part of building systems 😀 And it also gives you an excuse to load up on "spare" hardware just in case! Like buying more VLB controllers because the original one might be bad 😉

Reply 6 of 11, by b_rros

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ok, it's definitely a cpu problem, I resetead the VLB controller and change the IDE cable and the message about the HD controller went away.
I then tried with a different CPU, a 486 DX 33 MHz and the PC booted just fine and reset worked again, as soon as I put the DX2 on it again the problem reappeared...

Could there be some BIOS setting that is causing this? Because the computer works just fine, I've been playing DOOM without a problem, It just hangs in the reset process...

Last edited by b_rros on 2014-10-26, 10:43. Edited 1 time in total.

Reply 7 of 11, by feipoa

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Could you provide more information as to which CPU brands you are testing? I recall having an Am5x86-133 which would not soft reset. Repacing the CPU for another Am5x86-133 corrected the problem. Could you try a different DX2? Try another DX2 of the same brand and a DX2 of a different brand.

Plan your life wisely, you'll be dead before you know it.

Reply 8 of 11, by b_rros

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It's an Intel 486 DX2 SX645, I googled a bit and read that this model doesn't include SL features and does not support write-back, so mabe there's some setting in the BIOS I must deactivate, I turned off a few options regarding power management but the same thing happened...

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I do have another DX2 processor, it came with a IBM computer, I didn't remember that I had this one, I tried and reset worked just fine, I can't see what model it is because the heatsink is glued to the processor. Oh! And the processor is detectec by the motherboard as 66 MHz one

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Last edited by b_rros on 2014-10-26, 14:18. Edited 1 time in total.

Reply 9 of 11, by Anonymous Coward

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The CPU with "i50" on the bottom is more than likely a 50MHz part. Probably overclocking to 66 isn't going to be a big problem.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 10 of 11, by b_rros

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Yes, it's a DX2 50 MHz, it was from an old IBM...

That's what I'm doing right now, and so far so good, I was never a overclocker, but it's never to late 😀

I will try to buy another DX2 66 later on

Reply 11 of 11, by devius

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It could also be a jumper setting on the motherboard. I have a 486 motherboard that has a jumper for setting SL CPU or Non-SL CPU. Usually the CMOS setup screen in these 486 motherboards is a bit limited and a lot of the actual config has to be done with jumpers.