24
Aug
17

Motherboard: Another unknown Socket 3

Today I’m looking at another 486 socket 3 motherboard that unfortunately I can’t identify. Unlike the last one, this one actually had it’s model number on the silk screen, but the OEM who put it into a machine has covered the silkscreen label with either white paint or white out so that it is unreadable. Obviously this is a massive pain as I have no chance of finding a manual for this board, which is needed because of the large number of jumpers. I suspect they didn’t want end users finding out that it was a low quality board. Here’s a photo.

Again it’s a later 486 board as it has PCI slots rather than VLB slots. Reading the date codes on the chips reveals it was made in mid 1995, around the same time as the other socket 3 I have. The chipset was made by UMC, which I’m unfamiliar with. After having done some forum lurking over at VOGONS and reading some of the Red Hill Guide, it seems that it’s a fairly common chipset found on a variety of boards. I can’t comment on the performance myself, but others have had success getting decent performance out of their chipsets.

There are very few integrated peripherals, it has an old school DIN keyboard connector and two IDE ports, but strangely no floppy disk controller, serial or parallel ports. This ultimately wouldn’t have saved much money for the end user as they’d have to use add in cards to replace the functionality. Weirdly the IDE ports each use different styles of socket, another sign of cheapness.

The cache chips and system ROM are all socketed, which is a good sign that the cache is probably not a fake. The EPROM unfortunately had the sticker missing, exposing the window for the UV erasable chip. I’ve since put my own sticker over the window to protect it.

In an effort to identify it, I decided to pull the ROM chip and read it in my TL866 universal programmer. I was hoping to find a string that had the model name in it directly,but after an extensive search I only found the BIOS version string, “2A4X5B05”, which was enough to identify the manufacturer as Biostar but not the model.

Another unfortunate feature of this board is this real time clock chip with integrated battery. The idea is great in theory, but results in an unusable board when the battery runs flat, which it has.  Some of these RTC chips had the option of an external battery, unfortunately this isn’t one of them, so the only option I have is to either replace the chip (it’s not socketed) or hack it open and attach an external battery. Unfortunately this board doesn’t even remember the settings through a warm reboot, preventing it from actually booting an OS.

Like many 486 boards much of the basic configuration is done with jumpers. This usually means looking them up in the manual, but this board does have the basic settings for voltage, FSB speed and L2 cache size. Still there are obviously many more jumpers that are undocumented on the board, so the manual would be really handy. Luckily the silk screen has enough information you could install a CPU and not make the magic smoke escape.

At the time this board was made it was fairly low end, and windows 95 was just around he corner. It would have probably performed ok with MS-DOS and Windows 3.1, but would have been inadequate for Windows 95 when it came out later the same year. Most 486 machines didn’t really perform well with windows 95 so that’s hardly a surprise. The lack of integrated peripherals is probably the worst point with this particular board, as you’ll need add-on cards even for basics such as a floppy drive and serial port (which you’ll need for a mouse). Otherwise it would have made a serviceable, but not powerful machine.

Advertisements

3 Responses to “Motherboard: Another unknown Socket 3”


  1. September 16, 2017 at 7:17 am

    The 10-point JP12 looks suspiciously like it could be for a serial-port-via-standard-fly-lead, if the pins were present. It’s right at the rear side of the board, and the silkscreen makes it clear that it is intended for a single 2×5 2.54mm-pitch connector, not multiple 2-pole jumper blocks. Do the traces from JP12 go directly to the lower UMC chip?

    • September 18, 2017 at 4:39 pm

      Sorry for the late reply, my internet at home is not working 😦

      I agree that set of pads looks like a serial header that wasn’t populated, I’ll have to check the board when I get home to see where they connect. I suspect it would wire up to the pads for the missing chip just bellow it. I suspect that spot was for a keyboard/serial controller not needed with this UMC chipset that I’ve seen somewhere else. I’ll have a look at it later tonight.

    • September 18, 2017 at 11:28 pm

      I had a quick look and it wasn’t clear from the board, but it looked like they went to the pads for the missing chip nearby. It’s hard to tell because it’s a multi layer board without spending ages with a multi-meter.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


Blogs I Follow

Enter your email address to follow this blog and receive notifications of new posts by email.


Mister G Kids

A daily comic about real stuff little kids say in school. By Matt Gajdoš

Random Battles: my life long level grind

completing every RPG, ever.

Gough's Tech Zone

Reversing the mindless enslavement of humans by technology.

Retrocosm's Vintage Computing, Tech & Scale RC Blog

Random mutterings on retro computing, old technology, some new, plus radio controlled scale modelling.

ancientelectronics

retro computing and gaming plus a little more

Retrocomputing with 90's SPARC

21st-Century computing, the hard way

lazygamereviews

MS-DOS game reviews, retro ramblings and more...

%d bloggers like this: