3 Apr
2003
3 Apr
'03
9:48 a.m.
The Z90 is built to be 64K a H89 isn't. As far
as I recall, the H89 took more than a simple jumper or
switch to make it CP/M compatable.
Also, one should note that HDOS came in both hard and soft sectored.
Dwight
Dwight, I think you're right. Address decode is controlled by U516 and U517
on the CPU board... and those are PROMs of Heath's creation... close to
unobtainium. I have several different versions of each of these PROMs, but
I haven't yet figured out their contents and differences.
Oh, and regarding my earlier comment about the MTR EPROM... I went back and
looked at my old emails, and apparently there's more to the MTR-90 ROM
version story. You can use either 444-142 *or* 444-84 with the soft-sector
controller. Version 444-142 is reported to support both 40 and 80 track
drives; 444-84 supports only 40 track drives.
Tony, out of curiousity, what are your versions of the various PROMs and
EPROMs at U516, 517, 518, and 520 on your Z90?
Patrick