24 Sep
2008
24 Sep
'08
12:30 p.m.
I'm with Tony on the 40-pin socket as an 80287 spot.
Here are the switch settings:
Cached area (base)
1 2 3
Off Off Off disabled
On Off Off 0-256K
Off On Off disabled
On On Off disabled
Off Off On disabled
On Off On 0-512K
Off On On 0-576K
On On On 0-640K
4 to 7
Cached area (extended)
4 5 6 7
Off Off Off Off disabled
On Off Off Off C0000-CFFFF
On On Off Off C4000-D3FFF
Off On On Off CC000-DBFFF
Off Off On Off D0000?DFFFF
On Off On Off D4000-E3FFF
On On On Off D8000-E7FFF
On On On On DC000-EBFFF
Off On On On E0000-EFFFF
Off Off On On CC000-EFFFF
You're probably safe in leaving them all off to start with.
The 40-pin header as a plugin for the 8088 on the planar can be
verified by checking where the reset, data lines, and power wind up.
Some 286 add-ins don't require removal of the 8088; others do. And,
as Tony stated, it might go to a small daughterboard.
I suppose the header might be a memory add on, but with 24 address
lines and 16 data lines, that's not very likely.
Cheers,
Chuck