28 Nov
2007
28 Nov
'07
3:28 p.m.
[Slot 8 in a PC/XT]
Wasn't it used (and intended) for the expansion
chassis card?
Not as far as I can see. The XT 'Guide to Operations' states that the
only card that can go in slot 8 is the Async adapter (and it does mention
the epxaniso unit elsewhere, so it's obvious IBM were considering that
option in that manual).
Looking at the scehamtics for the Expanison Unit it the O&A TechRef, it
appears that pin B08 (the pin in question that has to be asserted on read
cycles) is passed on from the expansion unit to the main system, but that
the expanison unit itself never asserts it. So I suppose you _could_ put
the expansion interface card in slot 8, but then (a) the exp[ansion unit
self-tests oulw fail, and (b) the only thing you coulf put in the
expanison unit would be Async cards.
-tony