VOGONS


First post, by kanecvr

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Helo fellow retro hardware enthusiasts!

Today I got a haul of socket 3 and 386 motherboards, among witch I spotted a UMC based Biostar MB8433uud-a. All boards are rescued from a recycling center where they were going to be scrapped, and they were piled on top of each other outside in the open, so it wasn't in the best of shape. Besides the plethora of bent pins and part of a IDE cable stuck in one of the IDE connectors, the board had two electrolytic capacitors (10v 100uf) severely damaged and partly sheered off, one of the ISA slots is chipped, and it was covered in what can only be described as mud.

After a thorough cleaning, pin straightening and capacitor replacing, I got the board to POST. Now here's the problem: I can't seem to be able to locate a full manual for it - only jumper settings for different CPUs. The ODIN RTC's batery is dead - not even 0.1 volts - and the motherboard won't store any BIOS settings, making it impossible to boot of a HDD drive using the on board IDE controller (default setting is NONE instead of AUTO). Also, a curious fact is that it has a PS/2 port right under the DIN connector for the AT keyboard. Now I have no ideea if that's for a PS/2 keayboard or PS/2 mouse - the latter being most likely since the DIN connector and the PS/2 don't seem to share any traces apart from VCC and GND. The board also has a 5-pin connector that hasn't been solderede on - JP4 - witch I can only assume is also a PS/2 connector - either for KB or mouse.

Now to the questions:

- does anyone have a complete manual for this thing?
- can I connect an external 3V battery to it? I don't have a 4.6v battery nor do I want to look for and buy one.
- is JP42 the external battery connector? And if so, where do I stick the leads to a 3V battery?
- is the PS/2 port soldered under the AT Keypoard port for a PS/2 keyboard?
- was JP4 supposed to have a PS/2 mouse header on it? And if so, will a PS/2 mouse work if I just solder pins on? And if so, what pin arrangement does it use? Is it the classic Data/NC/GND/VCC/Clock?

Pics incoming.

Reply 1 of 10, by HighTreason

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The PS/2 connector is for a mouse.

I don't have the manual. You won't be able to feed an external battery to the ODIN because it does not have those pins, hopefully you have a socketed one (As BioTech removed the socket at some stage)and can replace it, you may be able to modify the Odin, but it's a pain to do; http://www.classic-computers.org.nz/blog/2009 … attery-chip.htm

But I don't remember much about the board layout and such, only that mine didn't work.

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Reply 2 of 10, by kanecvr

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New burning question - what are the jumper settings for 3.6v? The internets mention it can do 3.6v for cyrix 120 586 cpus, but I can only find 3.45, 4 and 5v in the manual...

HighTreason wrote:

The PS/2 connector is for a mouse.

I don't have the manual. You won't be able to feed an external battery to the ODIN because it does not have those pins, hopefully you have a socketed one (As BioTech removed the socket at some stage)and can replace it, you may be able to modify the Odin, but it's a pain to do; http://www.classic-computers.org.nz/blog/2009 … attery-chip.htm

But I don't remember much about the board layout and such, only that mine didn't work.

About the RTC: of course, you are right. Pins 16 and 20 needed for 3V battery are missing. Traces lead to the coin slot battery socket (witch you can't use anyway because of the PS/2 port)

Impatient as I am, I took off the ODIN RTC (It's socketed) and tore it down. Using my solder iron I burned into the plastic cover where pins 16 and 20 should be, then tested for voltage - 0.54v! Soldered a couple of wires on top leading to a battery holder witch I sutck on the RTC using electronics glue. Ugly as hell, but works great and allows me to swap out the RTC later.

Before:

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After:

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As you can see, the thing is still quite dirty. I removed as much mud as I could using isopropil put I ran out. I'll go again and clean it some more with medicinal alcohol until it squeaks. Still have some pins to straighten too.

As the impatient dumbass that I am, I went ahead and soldered a 5 pin header to what I tought was the PS/2 header for the mouse - then I saw your post and plugged in the mouse in the available PS/2 port and it works fine.

Sadly I only have one case this MB will fit in because of the extra PS/2 port - and I don't really like it much. It's a tiny baby AT case by JNC, w/o a turbo button of MHz display... I'll just have to add those later to a 5" bay...

Reply 3 of 10, by HighTreason

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Excellent, that has the potential to be a good board if it works properly. It has similar make-up to my Aquarius MB-4DUPM/E so I imagine it would perform similarly. I used to have an 8433 which I dismissed as being awful and it stopped working, but I now suspect somebody did something bad to it before I got it, given that it turned up with the CPU the wrong way and whilst I caught that before applying power, I'm not sure the previous owner did though as the board never ran stably and there were burn marks in the socket... In short, they probably are a good board really, they seem to get positive write-ups anyway and every other UM8881 PCI board I've used has been good.

I get what you're saying about the PS/2 port, I have a Socket 7 board with one and I would like to use it, but the case has no hole for it and the only one I have that does I don't want to change the contents of. Annoys the hell out of me as I have only one serial mouse - the first one I ever used is the last one standing, go figure - I've thought about removing the board and drilling a hole in the case for it, but I'm not sure putting holes in things is to everyone's tastes, also the last time I did anything like that it was a nightmare to get all of the metal dust out.

Good luck with the project, I'm sure you'll assemble a good system with it.

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Reply 4 of 10, by kanecvr

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I can't even drill a hole for the PS/2 in the rest of my cases since the I/O card holder (metal bracket thing that the expansion cards crew into) is intruded 1cm unto the case, so it still would not like up. I do have to say, in my quest for modding jumper 17 witch allows you to select 50MHz FSB I almost killed the board... somehow my the jumper bar I put in wrecked the inside of the contact point so that it would not lead anywhere. Luckily, I managed to figure out where the pin is supposed to go - pin 4 of the clock generator - and jerry-riged a patch on the back of the motherboard...

Phew...

The thing scores fantastic I must say - over 70 points in speedsys with the cyrix at 120mhz and enhancements on - unfortunatly it's not stable at that speed due to the low voltage, and I don't want to give it 4V.

Reply 5 of 10, by HighTreason

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Yeah, my cases have a different problem whereby the DIN is behind a metal shield which when removed leaves the port half obscured by the chassis, making it hard to drill in the correct place... I suppose I could use a metal file or maybe I'll just have to give up and track down another serial mouse.

Good to know it scores well, I don't know much about speedsys metric so I'll be testing my 4DUPM to see how it compares. Your board is alleged to support EDO RAM, but I have never heard of anybody getting that to work, there are also undocumented BUS speeds... But I don't remember the settings for them, you'll probably never use them anyway as they're a pain to get working... Open Closed Open I think it would be on your board for 60MHz, but the Cyrix will never POST at that speed.

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Reply 6 of 10, by kanecvr

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Well, I broke JP17 traces trying to get that 60MHz and got stuck with 60MHz only 🙁 Like I said, I managed to make a patch directly to the VRM so I can get 33MHz again.

The cyrix DOES post at 2x60, but freezes soon after. Luckily it worked at 1x and at 60MHz it's stable but slow. My problem is it's not stable at 3x40 and I don't know how to fix this. The AMD 586 you sent me works fine at 4x40MHz - score 16.6 FPS in quake with an Alliace card! Boots into windows fine too. The cyrix is quite a bit faster at 120 so I'd like to use that.

I measured output voltage from the board - when set at 3.45, it gives 3.6v. At 4V it give 4.22, and at 5V it gives 5.25v. Something is WRONG. Normally, 3.6 would be what I'm looking for to get the cyrix to run stable at 120 - but it won't. Maybe more bad caps? Maybe the regulator is failing?

Like I said in the first post, I got a lot 8 or so of motherboards - some are combo boards that support a 486 or a 386. I'll post some pictures, and if you fancy any of them, please tell me and I'll test it and send it/them to you in exchange for the 586 cpus. I also got a couple of baby at 386 boards with a soldered AMD 386SX at 33MHz. Two have VLB and ISA slots + SiS chipset, and one of the two has a 386 socket (it's not soldered to the board, but I can fix that 😁 ).

The 4DUPM looks sweet. UMC + VLB might be an awesome combo - let me know if you get it running.

In speedsys, 71.4 is pretty fast - pentium 100 equivalent if i'm not mistaking. The AMD 586 scores 61.92 - pentium 75 equivalent.

Reply 8 of 10, by kanecvr

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I read both threads, thanks for the links.

Right now, I'm searching for a way to get the Cyrix stable at 120MHz (3x40Mhz). As it is, it crashes quake and hangs in duke3d after a few minutes. I don't think it's a voltage issue, since the chip ran fine at the same voltage in my FIC 486-VIP-IO. Tomorrow I'll try updating the board's BIOS and playing with some BIOS settings and swapping some simms. I read someware that using FPM ram might fix the issue.

Could also be more damaged capacitors. Unfortunately my capacitance meter died a couple of days ago and I can't test them. Will have to wait until I can afford a new one.

Reply 9 of 10, by HighTreason

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Test the PSU whilst it is connected to the board just to be sure that the voltages aren't drifting ridiculously out of spec on that. Burning traces is never a good thing. It could indeed be related to caps though as you say, or the VRM. After my BioStar I got some Elpina/PCChips board and the voltage regulator had died on that, it did very strange things until I added a new one. Overclocking never comes with guarantees though of course, a lot of it is simply pressing the power button and hoping it works.

Let me know when you get that stuff and I'll have a look, but I probably won't take anything as I'm overcrowded with parts as it is, still, might be something that sparks my interest I suppose.

The 4DUPM/E is indeed good, at least as far as I have tested it. That project has been on hold for a while, so it still needs a CD-ROM installing, the video card needs new RAM (Surface mount SoJ... Yuck!) and I have to make up a cable for the VCD decoder I'll probably never really use. I'll run SpeedSys when I get home tomorrow, though it will probably be on the POD and so the results will be slightly skewed. It's "little sister" machine with a 4DUVC is on Phil's VGA database running other benchmarks with a few CPUs in, it uses the older UM8498 chipset and lacks PCI but seems to perform similarly to the 4DUPM otherwise, normally that has a 40MHz U5S installed though so it is not running to it's full potential.

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Reply 10 of 10, by kanecvr

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PSU is fine - 5.12V on the 5V line. Swapped to another PSU - same issues.

Here's a pic of the Biostar running quake with the AMD 586 at 160MHz and an Alliance Promotion 3200 video card - 16.6FPS! Would have been 17 with an S3 card 😁 It's rock solid with the AMD chip at 160MHz (2x40MHz, 4x internally) but acts up with the cyrix at FSB 40.

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In 10 mins or so I'll upload pcs of the motherboards I got and PM a link to you. Will also post it here for good measure.

EDITED - here's the link I promised. If you fancy anything, PM me. Re: Help identify some old hardware - motherboards, video cards and some weirder stuff.