3 Apr
2003
3 Apr
'03
10:34 a.m.
From: ard(a)p850ug1.demon.co.uk
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
MTR-90 is in the ROM on the 89's CPU board.
My MTR-90 manual indicates
[...]
It certainly seems as if you can run both
controllers in one machine.
You most certainly can. My Z90 (essentially the same machine -- AFAIK the
differences are that it came fully assembled ('Z', not 'H'), and came
with 64K RAM, has MTR-90, the hard sector controller and the
double-density soft sector controller. The former is cabled to the single
built-in drive, the latter to an external drive box.
It will boot either HDOS or CP/M, and can use both types of disks
-tony
3 Apr
3 Apr
12:48 p.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
1:45 p.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.
IIRC, there were modified PROMs for CP/M-capable machines, which allowed
the memory to be re-mapped with RAM at address 0. Older version CPU
boards need a jumper wire (from an output port bit to a pin on the PROM,
basically) for this, I think it's a trace on later boards.
Tony, out of curiousity, what are your versions of the
various PROMs and
EPROMs at U516, 517, 518, and 520 on your Z90?
That would involve getting to the Z90, which is not going to be trivial....
-tony
2:12 p.m.
I have, of course, dumps of the 2 proms (one is 32*8,
the other 256*4) in
my Z90. They're a lot less 'unobtainium' than many chips I deal with!.
That's good news, because I have a few CPU boards I'd like to upgrade... so,
modern equivalent blanks are available? I haven't ripped labels off of any
of them to see what they really are.
Tony, out of
curiousity, what are your versions of the various PROMs and
EPROMs at U516, 517, 518, and 520 on your Z90?
That would involve getting to the Z90, which is not going to be
trivial.... 
2:30 p.m.
I have, of
course, dumps of the 2 proms (one is 32*8, the other 256*4)
in my Z90. They're a lot less 'unobtainium' than many chips I deal
with!.
That's good news, because I have a few CPU boards I'd like to upgrade...
so, modern equivalent blanks are available? I haven't ripped labels off
of any of them to see what they really are.
4 Apr
4 Apr
6:48 a.m.
> Tony, out
of curiousity, what are your versions of the
various PROMs and
> > EPROMs at U516, 517, 518, and 520 on your Z90?
>
> That would involve getting to the Z90, which is not going to be
> trivial....
1:39 p.m.
I have, of
course, dumps of the 2 proms (one is 32*8, the other 256*4) in
my Z90. They're a lot less 'unobtainium' than many chips I deal with!.
That's good news, because I have a few CPU boards I'd like to upgrade... so,
modern equivalent blanks are available? I haven't ripped labels off of any
of them to see what they really are. Tony, out
of curiousity, what are your versions of the various PROMs and
EPROMs at U516, 517, 518, and 520 on your Z90?
That would involve getting to the Z90, which is not going to be
trivial....
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6 comments
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participants (4)
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ard＠p850ug1.demon.co.uk -
dwightk.elvey＠amd.com -
eric-nospam-638＠brouhaha.com -
patrick＠evocative.com