Vintage Motherboard

This is a good one! That's the motherboard from a Tandy 1000 RSX, the last of the popular Tandy 1000 line. (It's also possible that it's from a 2500 RSX, which used the same board but not all the same chips. I'd need closeup photos to be sure.) The design of the board is a bit weird -- it's smaller than a piece of letter-size paper, and it has just one 16-bit ISA slot, which is parked right in the middle of everything. And the 1000 RSX is a pretty weird computer:



I don't know if you can tell from this picture, but the hard drive is actually screwed directly onto the bottom of the case! I don't think I've ever seen that done in any other computer. The big black bracket that's attached to the case at a 45° angle is there to support the card that's inserted into the ISA slot. When you see that, you have to wonder why a little card like that would be supported by such a hefty metal bracket. There is a clue: Since the mainboard has just one expansion slot, that probably is supposed to hold a daughterboard, or riser card, which has a normal number of expansion slots on it. Instead of expanding horizontally with various cards plugged directly into a large motherboard, the computer would expand vertically, with cards stacked parallel to the mainboard. And in fact, there was a riser card for this computer, which the user would plug into his one and only ISA expansion slot. But this is where the RSX's design gets really wacky. The riser card contained just 2 ISA slots. So to give their customer a measly 2 expansion slots, instead of just putting them on the motherboard, Tandy incurred the extra costs to produce a separate riser card and install 3 ISA connectors. At the top of the next picture, you can see the riser card with its 2 (!!) empty ISA slots:



I really can't figure out why Tandy didn't just put both slots on the motherboard. I do know, though, why they put only 2 slots on the riser card: They couldn't expand any further vertically and still fit everything inside the 1000 RSX's case. They had given it a slimline case, and the machine was only about 3" tall! Apparently, there was another company that did make a riser card with more slots for this Tandy. Anyone who bought that card just had to leave the top off their computer case so they could use it. ¯\_(ツ)_/¯



In spite of its quirks, the Tandy 1000 RSX is very collectible, in part because it's the last Tandy 1000 model and includes their 3-voice sound chip. You don't have the rest of the computer over there somewhere, do you? A collector would buy that in a heartbeat!


[Edit] Almost forgot to give credit for those photos, which are not mine: http://www.oldskool.org/guides/tvdog/RLRLX.html