The Biostar 8500TAC is a plain i430FX based, Baby-AT Size Mainboard for Pentium Class CPUs. They make brave workhorses, still fast enough for office use or Workgroupservers. Nothing more, nothing less.

Not much to say here. Only the versions with the mouse-port beside the keyboard connector will need a case with a hole there. If you don't have such a box, you may wish to use the internal connector and a bracket with a mouse port. Check the jumper settings for your revision for the layout. Otherwise just as any other board.

Biostar still offers a quite recent Bios-Upgrade. The Upgrade itself depends on the I/O-Chip mounted.
Here is the latest BIOS and the previous version.
On the page for the previous version is a great diagram, how to locate and identify the I/O-Chip

My enhanced Jumper-settings for the different versions:

Biostar states that Ver 1-3 support only intel CPUs.
Ver. 4 and 5 offer split voltage support, but the Core-Voltage of 2.5V is useless. Do not try to use any 2.2/2.4V AMD K6-2/III in this board, because you've heard that they will work with 2.5V also. The power plane is far too weak to feed the needs of such a CPU.
The dual voltage design is also useless to any other AMD and Cyrix/IBM CPUs.
Ver. 6 changed the core-voltage to 2.8V and may support MMX-CPUs. Due to spec changes from intel for the MMX-CPUs, this might not work, but you have a good chance. I never tried it so far, due to lack of such a CPU.

So what CPUs do actually work?
Native intel Pentium up 200MHz should work on all boards, even on the older ones. All necessary jumpers are there and the power drawn from the onboard supply isn't that much different between a -180, which is supported by all revisions and a -200
Nevertheless, watch the temperature of the voltage regulators if you install any fast intel, Cyrix or AMD-CPU.
The AMD-K5 and Cyrix 6x86 should work on all boards, maybe at reduced speed.
All IDT-CPUs should work on all revisions. Avoid all versions which need speeds faster than 66MHz (for example the 225 MHz versions), because the board will not provide more than 66MHz.
Pentium Overdrives will work, but you may need the latest Bios Update.
Cyrix_CPUs (6x86L, 6x86MX, MII) and the AMD K6/-2/III will not work, because they need either a different core voltage or the power plane is too weak or both.
Using an adapter socket *should* make nearly every CPU work.

So, what are the real differences between the revisions?

Rev. 1 Dual Voltage Design #1 (2,5/3.5V) UMC I/O No I/R Mouse int/ext
Rev. 2 Dual Voltage Design #1 (2,5/3.5V) SMC I/O I/R Mouse int
Rev. 3 Dual Voltage Design #1 (2,5/3.5V) SMC I/O I/R Mouse int
Rev. 4 Dual Voltage Design #2 (2.5/3.5V) UMC I/O No I/R Mouse int/ext
Rev. 5 Dual Voltage Design #3 (2.5/3.5V) UMC I/O No I/R Mouse int/ext
Rev. 6 Dual Voltage Design #4 (2.8/3.5V) UMC I/O No I/R Mouse int/ext

Neither version features a COAST Socket.

This board was also sold by other companies, using different names.

Here is a Quantex/Inteva vs. Biostar comparison
MBD-P5CBUMC I/OAsync CacheRev 1
MBD-P5RBSMC I/OAsync CacheRevs 2/3
MBD-P5SBSMC I/OPB CacheRevs 2/3
MBD-P5YBUMC I/OAsync CacheRev 4, maybe 5/6 too
MBD-P5YB0UMC I/ONo CacheRev 4, maybe 5/6 too
MBD-P5ZBUMC I/OPB CacheRevs 5/6, maybe 4 too

For example check out here.

If you have questions, contact me

Last Update: 07/26/2001