Today’s motherboard is from a Taiwanese manufacturer called Biostar Microtech International (know as Biostar for short). They are one of the old guard of PC motherboard manufacturing having started in 1986, although until finding this board I haven’t used much or any of their hardware. In the past Biostar have made boards for OEMs as well as the high-end, mid and lower-end of the market. These days they seem to be focusing on higher end parts. This particular example is a M6TBA ver 1.3 which from the date codes on the board appears to be made in 1998.
Here’s an overview of the board.
It supports slot 1 processors up to 800 Mhz surprisingly, this would have been faster than any of the Pentium II chips available at the time. It was probably a forward looking design, perhaps with the capability to support a Pentium III in a slotket, although this isn’t documented in the manual. The slot 1 system was implemented by Intel for a few reasons, but mainly they wanted to move away from the ageing socket 7 standard, partly because it was limiting the memory bandwidth and partly because it was used by many of their competitors.
They initially designed another socket, which was called socket 8, this saw limited production as there was a problem with how the cache was integrated onto the CPU. It actually had two separate dies on the one package, which proved to be a production problem that increased wastage when either a cache die or processor die turned out to be faulty. The slot 1 design solved this problem by putting the CPU and cache in separate packages on an installable module. They did miss an opportunity to put the voltage regulation on the module, which would have made the slot 1 more flexible and future-proof.
The board is pretty standard fair for it’s time, having an Intel chipset ( 82243bx being the north bridge) with PCI, ISA and AGP slots, which were all fairly standard for the time. It supports up to 384MB of RAM in three 128MB SDRAM modules, which was quite alot of memory at the time. Many people had 64Mb-128Mb.
Here’s a close up of the front panel header and the CPU configuration jumper block (the ones with yellow jumpers). The front panel is marked, adequately, but not really nicely. The CPU configuration block has no markings at all, requiring you to look up the manual, which luckily is still available. Looking at this block it is unclear what speed of CPU was installed, as according to the manual these settings don’t match any of the speeds. Perhaps the board can detect the speed automatically.
An unusual feature of this board is the un-populated footprint next to the main power supply connected. It looks like a large heatsink was to be attached to the board with a linear voltage regulator, something you don’t normally see. It could be leftover from when the board was in the prototype phase, and thus not used in production, but still on the layout. Whatever the reason, the size of the heatsink foot print leads me to believe it was going to be dealing with a significant amount of power.
Speaking of power supply, check out the bulk capacitors next to the CPU slot.
Some of the capacitors are visibly bulging, a sure sign they are failing. Sometimes a board will continue to function like this, but it usually means the board is about to fail. You can replace these components, but it’s tricky soldering on these multi-layer boards, it’s easy to damage them. It’s something I haven’t been brave enough to attempt yet.
Another interesting feature is this chip here, an SMC FDC37M602. It’s a Super IO chip which integrates floppy disk controller, serial ports, PS/2 ports and a parallel port. It’s quite some distance from the boards floppy connector, so I’d say the chipset is supporting that, at a guess I’d say this chip is driving all the rear port with the exception of the USB ports.
The thing I noticed however was the copyright notice on the chip, the date reads 1994 from a company called American Megatrends, a software house known for writing BIOS ROMs for PCs. This particular board however uses an Award BIOS which of course comes from a rival company! Not so much a technical achievement, but interesting to see.
Beginning to sum up this board, it’s not really ideal for the technician working on it. Mostly due to the CPU configuration jumpers having no markings at all. Otherwise it’s very similar to working on other boards of the same vintage. This would have been a more expensive board at the time, mostly because Intel boards and CPU’s tended to be more expensive. It has lots of standard slots allowing for upgrades and expansion. So it’s not all bad, just a bit inconvenient to change CPU with.