16 Nov
2000
16 Nov
'00
4:43 a.m.
At 10:59 AM 11/16/2000 -0500, you wrote:
I haven't played with mine in a while, but was
reminded
of this by a comment in a current ebay auction. Whenever
I put a Cromemco 16FDC or 64FDC in an IMSAI box, the front
panel stops working (the 4FDC doesn't do this). Looking
at the schematics for the Cromemco boards, I can't see any
reason for this, but watching the behavior of the FP lights,
it looks like the board is driving the data bus whenever a
wait is asserted. Can somebody else with the 16FDC or 64FDC
schematics take a look?
It was how they implemented the RDOS shadow ROM. There was a Cromemco
tech-note that came with the 16FDC that showed some mod to allow it to work
with the IMSAI front panel. IIRC, the result was you had to key in
something like three bytes of code to get it to boot automatically from the
floppy.
--Chuck