What are you planning to do with it, what are your requirements? Do you know the brand and model?

A cursory glance indicates its probably pretty good... socketed cache chips, 72-pin SIMM slots (easier to find in greater capacity than 30 pin), onboard IDE/FDD/Serial, possibly PS/2 mouse as well. VRM near the CPU socket suggests it supports 3.3V CPUs. That ODIN thing looks like a DS1387-type RTC battery so you don't need to worry about leakage or soldering to replace batteries. UMC chipsets are pretty good in my experience, and perform quite well.

so yeah, seems ok 😀

Looks like a Biostar mobo, I think RG100 has one...

I was planning to use it for overclocking experiments. i was hoping it wasn't another PC Chips design. I found one that looks very similar here: http://motherboards.mbarron.net/models/486pci/pt432b.htm

Diagram

http://motherboards.mbarron.net/models/486pci/pt432b.gif

Photo

http://motherboards.mbarron.net/models/486pci/pt432bp.jpg

The layout is virtually identical but you can see the board is a different color and the traces are not identical. There are also some parts present on one board but not the other. The two probably came out of the same factory, at the very least.

Ooh I think I found it on Stason

http://stason.org/TULARC/pc/motherboards/B/BI … 486-MB-101.html

Biostar MB-8433UUD-A VER:2

I wonder if this revision 2 mobo supports EDO RAM? Vogons user feipoa said "if the UM8881F chipset has an E, as shown below in the given location of -EYT, then it supports EDO RAM.

UM8881F
9633-EYT
R62706

I think it's worth checking this, before you buy it. If it does support EDO, it certainly looks good enough. It does support the P75 CPU, and has a PS/2 port. BTW, if the battery inside the ODIN RTC is flat, you can replace it with a similar Dallas RTC. They are much more common.

BTW sliderider, how did you get on with your PC Chips UMC 486 mobo?

retro games 100 wrote:

BTW sliderider, how did you get on with your PC Chips UMC 486 mobo?

Everything hobby related is on hold temporarily except for buying a few things here and there until I have time to clear some space and put some things into storage so I'll have room. I just wanted to grab this in case I never saw one again.

How did one of these land in your lap? There have been two of these on eBay for the past little while, but the prices were outrageous, $100-$200 USD.

This is a Biostar MB-8433UUD v2.0. I had two of these boards in the past but toss 'em in favour for v3.0 and v3.1. I tried updating one to the latest bios version, UUD960520 but it ruined the v2.0 board's BIOS and I could not revert back. I think you need UUD960306 or later to support EDO ram.

i.e. UUD960306i = 1996, March 06, Intel style BIOS update.
If your BIOS version ends with an i, it uses the Intel style update. If it ends with an s, it uses the SST style update. I don't think you want to cross-mix the update styles.

If you bought the board I looked at awhile back, I think it was UUD951202. Generally speaking, I have not noticed much of any speed enhancement with EDO vs. FPM RAM of the same nanosecond speed rating.

feipoa wrote:

How did one of these land in your lap? There have been two of these on eBay for the past little while, but the prices were outr […]
Show full quote

How did one of these land in your lap? There have been two of these on eBay for the past little while, but the prices were outrageous, $100-$200 USD.

This is a Biostar MB-8433UUD v2.0. I had two of these boards in the past but toss 'em in favour for v3.0 and v3.1. I tried updating one to the latest bios version, UUD960520 but it ruined the v2.0 board's BIOS and I could not revert back. I think you need UUD960306 or later to support EDO ram.

i.e. UUD960306i = 1996, March 06, Intel style BIOS update.
If your BIOS version ends with an i, it uses the Intel style update. If it ends with an s, it uses the SST style update. I don't think you want to cross-mix the update styles.

If you bought the board I looked at awhile back, I think it was UUD951202. Generally speaking, I have not noticed much of any speed enhancement with EDO vs. FPM RAM of the same nanosecond speed rating.

This one was in a junk lot that was being sold for gold recovery so I convinced the seller to cull it for individual sale. He had a lot of other scrap boards so he threw one of those into the scrap lot to make up the weight. For all I know it may not even work or maybe the RTC battery is just dead but I couldn't believe it when I saw it in the photo, just sticking out like a sore thumb so I contacted him and got it.

I've seen 486 PCI boards in scrap lots before but they've always had ALi, SiS or Opti chipsets on them and those don't have the 60/66 bus speed jumpers. There's actually a few on ebay now mixed in with the scrap but like I said, not any with the UMC chipset on them that I was able to see and even though you might be able to get an individual board cheap, you take the chance that it might not work when you get it.

Are the BIOS chips socketed on these? Instead of flashing, can you swap the chip without damaging the board?

sliderider wrote:

retro games 100 wrote:

BTW sliderider, how did you get on with your PC Chips UMC 486 mobo?

Everything hobby related is on hold temporarily except for buying a few things here and there until I have time to clear some space and put some things into storage so I'll have room. I just wanted to grab this in case I never saw one again.

Wow, that sounds awfully familiar! 😁

sliderider, yes the BIOS chips are socketed. I think there is a jumper setting on the MB to set the BIOS ROM voltage for either Intel (12V) or SST (5V). JP13, 1-2 for SST, JP13, 2-3 for Intel. Unfortunately, I do not have a v2.0 board to stick my 3.0 or 3.1 BIOS into to test. I'm certainly not paying $100-$200 on eBay to test this possibility!

When you have a chance, report back with how this 2.0 board works out.

Look at this

http://www.elhvb.com/mobokive/Archive/Biostar … manuals/uud.htm

According to this, JP42 allows the connection of an external battery in addition to clearing the CMOS settings. Maybe you don't have to hack or replace the Odin/Dallas battery at all when it dies?

For me,

I like the layout of the board :

1. The CPU socket is moved away from the expanson slots area, and sits nicely in a far away corner. Most boards have cpu sockets stuck just opposite of the pci slots or worse still, in front of or next to the ISA slots. Most ISA cards are quite long, and some medium length cards will have trouble sitting beside the cpu heatsinks.

2. There is NO sharing of PCI-ISA. No need to compromise on the selection of PCI or ISA card dilemma, if you are installing a "handful" of cards. I like these non-sharing, separated PCI and ISA-slots boards.

3. Has PS/2 (?)mouse connector onboard. Makes the use of optical mouse (and hence, avoiding cleaning of ball mice) possible.

4. UMC chipsets are reliable. (As far as I have experienced.)

But!:

a. I don't like these real-time clock batteries and barrel batteries. Replacing is a bit harder, more so for the barrel types. And finding an external battery with connector is also hard. Coin-cell types (CR2032) are best.

b. The PS/2 port - though it is useful, I prefer to have a board with connector pins instead of built-in port on an AT/Baby AT motherboard. For one, external PS/2 connector with bracket will fit in nicely in an expansion bay of the casing. Most AT casing will only have bored hole for the AT-keyboard connection alone. And most of these casings wil render these on-board PS/2 connectors useless, because it will be covered by the casing. Still, one can make an opening, by making a bore hole on the casing.

Re: PS/2 port. Luckily that board has a PS/2 header. It's immediately behind the PS/2 port - row of 5 pins.

retro games 100 wrote:

Re: PS/2 port. Luckily that board has a PS/2 header. It's immediately behind the PS/2 port - row of 5 pins.

Didn't know such a feature even existed. Thx for pointing it out, it'll be the first thing I check when browsing through my AT boards again 😉

retro games 100 wrote:

Re: PS/2 port. Luckily that board has a PS/2 header. It's immediately behind the PS/2 port - row of 5 pins.

[On a page from Dr. Watson's diary]

9th of April entry :

My friend Sherlock Holmes, again shone with his extraordinary observation skill! Simply splendid!

😁

I must confess Watson, it was my smarter brother feipoa who spotted this, on another thread! 😉 😀

retro games 100 wrote:

Re: PS/2 port. Luckily that board has a PS/2 header. It's immediately behind the PS/2 port - row of 5 pins.

You can still use a serial mouse with these boards, though, right? The case I have has a hole for the old style keyboard but not one for the PS/2 mouse port so I'm thinking I'm going to need to use a serial port card and mouse.

Yes, you can use a serial mouse, but why not use a better optical PS/2 mouse instead? You say you do not have a PS/2 "hole" for one at the back of the case, but you don't need one. Simply attach a PS/2 cable to the mobo's PS/2 header pins, and then mount the cable's "output bracket" inside the case in the same way you would mount any add-in component card, such as a VGA or a sound card, or a NIC, etc. Like this one -

BTW, you'll need to get the correct PS/2 cable. There are two types floating about on the net. One with 2 rows of 4 pin holes, the other with 1 row of 5 pin holes. You need the 1 row of 5 pin holes plug version. You'll also need to check the wiring with a multimeter. I wrote about this on Vogons recently. It's here.