very early 386 motherboard on ebay

[romanon]

I fonded this motherboard on ebay, can someone tell something about it? Why is there reduction and 287 coporocessor? Why three power supply connections and what type is that long bus on motherboard?

http://www.ebay.de/itm/Mainboard-Or...13?pt=LH_DefaultDomain_77&hash=item1c54b9bd89

 

[bear]

The 80387 wasn't available until later.

The long card sockets are 32-bit sockets for memory adapters. You may have noticed there isn't any room on the board to have provided for RAM upgrades. The memory boards will be more or less unique to this machine. It was a relatively common arrangement in the pre-SIMM '386 days, and not unheard-of in the post-SIMM '386 days either. I had a 40 MHz DFI board that took SIMMs, but only two banks on the motherboard. The other two banks were on a plug-in card with a similar slot to the one on this board. But I doubt they would've been compatible. The 8-bit portion of the slot works like any other 8-bit ISA slot. Some boards had the ability to use regular 16-bit cards in the extended slot, too.

 

[KC9UDX]

That was a pretty common board. I don't recall having a memory card for it but I must have had.