VOGONS


First post, by soviet conscript

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never had a EISA board before and was graciously given this one recently but I can't get it to post or even get a speaker error beep. I've tried various known working RAM and an 486 DX50 and 486 66mhz DX2 ( don't know if it even supports DX2s though. any advice or info on this board? switch says it supports SX and DX 486 CPUs. I do see a few things that seem to be missing like a crystal oscillator (this board has 2) but I wanted to ask here to see. There are also two of what appears to be Dallas RTC chips in the upper right-hand corner, why 2?

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Reply 1 of 16, by Deksor

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It's a ASUS motherboard http://www.win3x.org/uh19/motherboard/show/801

I believe one of the dallas chips is used to store the EISA settings and the other the regular CMOS settings.

Trying to identify old hardware ? Visit Ultimate Hardware 2019 - Project's thread The Ultimate Hardware 2019 (UH19) project- a stason.org/TH99
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Reply 2 of 16, by TheMobRules

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Looks like the motherboard has a 33MHz oscillator and an empty socket for another one. By looking at the jumper settings, it seems that JP4 (near the expansion slots) is used to set the bus speed. I assume it toggles between the two oscillators (the missing one would be a 50MHz part).

Currently, it is open, which according to the settings should be for 50MHz, so try and close that jumper to see if it works at 33MHz FSB with a DX or DX2 CPU.

Reply 4 of 16, by Horun

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And you may need this EISA stuff from Asus archives. the zip file has !ASU4201.CFG for EISA-486A and the eisa config utils.

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Hate posting a reply and have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. 🤣 Second computer a 286 12Mhz with real IDE drive ! After that came 386, 486, Pentium, P.Pro and everything after....

Reply 5 of 16, by mkarcher

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majestyk wrote on 2021-05-06, 18:07:

As long as you have populated 128KB of L2 Cache and jumpered it for 256KB, the board will not post.

That's unusual. Normally, L2 is enabled only after POST, so the board should POST even with bad cache jumpers. Some boards even perform basic cache checks during POST and do not enable L2 if it fails. Typical symptom for bad cache (if not caught be the POST) would be a crash after the POST is complete, often after printing the "system configuration" box.

I still remember installing Win'95 on a friend-of-a-friend's 486 computer back in the day, and the process seemed extremely sluggish. After completion of the setup, I checked the CMOS setup, and it said "external cache: disabled" and "internal cache: disabled". I switched both to enabled, and after resetting the machine, I got the message "CACHE MEMORY BAD, DO NOT ENABLE CACHE" on the next boot. Of course, this message only applied to the L2 cache, and L1 could have beed enabled all the time. The issue with the cache chips was that they were made from 78% nitrogen, 21% oxygen, and 0% plastic, copper and silicon.

Reply 6 of 16, by Horun

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mkarcher wrote on 2021-05-06, 20:31:

The issue with the cache chips was that they were made from 78% nitrogen, 21% oxygen, and 0% plastic, copper and silicon.

😁 Yeah have a few boards that when had bad cache would start post and halt.

Hate posting a reply and have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. 🤣 Second computer a 286 12Mhz with real IDE drive ! After that came 386, 486, Pentium, P.Pro and everything after....

Reply 7 of 16, by soviet conscript

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I'll set the jumper to 128k and close JP4 with a 33mhz CPU installed and let you guys know, thanks for the ideas so far. If I want to install a 50MHz DX does my oscillator crystal need to be rated 100MHz or 50MHz?

Reply 8 of 16, by Anonymous Coward

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The board you have is blessed with not one, but two of those battery backed chips behind the ROM BIOS. It's almost 100% certain that the batteries are dead. One of them should be a standard 1287 timekeeper, and the other holds the EISA config settings. I think later boards used chips that unified these two functions like the 1387 and the 1488. I would replace the 1287 clone first, because those are relatively easy to find.

I would start with those. Also check in all the EISA slots and SIMM sockets to make sure there aren't any shorts. Check the board carefully for deep scratches, or bad joints.

BTW, please dump the ROM BIOS on this board if you are able to.

"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 9 of 16, by TheMobRules

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soviet conscript wrote on 2021-05-07, 00:05:

I'll set the jumper to 128k and close JP4 with a 33mhz CPU installed and let you guys know, thanks for the ideas so far. If I want to install a 50MHz DX does my oscillator crystal need to be rated 100MHz or 50MHz?

Most likely a 50MHz oscillator since the other one is 33MHz. That board doesn't seem to use any dividers for the bus frequency, same as the ASUS ISA-486 for example.

Reply 10 of 16, by soviet conscript

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Unfortunately no luck. I switched the jumper for cache to 256k. I tried again with a 486 66mhz dx2 and tried jumper j4 on and off. Tried more ram, tried both setting for the jumper that controls what crystal the board uses with the cpu. Visual the board looks immaculate. Despite everything it won't post. I also never get any error codes from the speaker. The chips on the motherboard do get warm if I leave it powered on for awhile but the cpu stays cold.

Last edited by soviet conscript on 2021-05-07, 15:37. Edited 1 time in total.

Reply 11 of 16, by Anonymous Coward

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Did you use a multimeter to check the 5V lines? What about shorted filter capacitors? Normally they explode and catch on fire leaving a scorch mark making them easy to spot. But sometimes they don't.

"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 12 of 16, by Miphee

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I had a similar IBM board with 2 Dallas chips and it didn't work either. Traces and caps were fine, chips warmed up, ROM contents were okay, PSU was good but nothing. I even modded and socketed the Dallas chips and still nothing. I just gave up. I suspected the Dallas chips going bad but didn't want to spend more time on it.

Reply 13 of 16, by TheMobRules

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You know, a few weeks ago I was having similar symptoms on a 486 motherboard. All the chips would get warm except the CPU and there were no signs of life at all. After checking everything I could, I decided to replace the oscillator with another one. No particular reason for doing that except it was socketed, so it would be easy.

I installed a similar oscillator and it worked right away, turns out the original one was broken! I don't know how often these things fail, but it's worth a shot if you have any lying around. Also try populating the empty oscillator socket just in case!

Reply 14 of 16, by Anonymous Coward

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According to TH99, JP4 should be:
CLOSED for 20 and 25MHz, and OPEN for 33 and 50MHz.
As the jumper settings for 33 and 50MHz are identical, I am really sceptical that JP4 determines which oscillator to use.
I think both are probably needed for operation. In this photo, both oscillators are zip tied in place (probably by the manufacturer).
http://www.win3x.org/uh19/public/motherboard/ … f2071720467.jpg

If you could find the actual user manual you could know for certain.

"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 16 of 16, by soviet conscript

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I've ordered new 33.333mhz and 50mhz oscillators so we will see.....

there is another jumper other than jp4 which I interpreted as chooseing an oscillator but maybe I was wrong.

I have a multimeter but I must shamefully admit I've never learned how to use it to check lines or caps but I suppose its probably something I need to learn how to do. any good "how to" video suggestions?