17 Aug
2015
17 Aug
'15
5:40 p.m.
You should be able to get a replacement NMOS Z80 from Jameco for four or
five bucks ... if you put a 5V CMOS Z80 in there, I wouldn't expect it to
really hurt anything; it might not run exactly right depending on
tolerances in the system design I would suspect mostly due to (a) logic
threshold differences and (b) fan-out differences especially given one
logic family driving another ... but I wouldn't expect it to really damage
anything.
I have a mostly working Executive ... logic is OK but the screen will roll
when the environmental conditions are just right (probably some caps are
getting dodgy, or a cold solder joint) ... it's usable ... I have all the
original media and documentation; plenty of bootable floppies; I've got a
sleeve of 5.25" blanks and I could run off a few duplicates for you ... not
sure if these will work on the Osborne 1 ... if you're in the USA and you
want to give some of the media from the Executive a shot, maybe I could
help you out.
Best,
Sean
On Mon, Aug 17, 2015 at 1:48 AM, drlegendre . <drlegendre at gmail.com> wrote:
Thanks for the input, gents..
Sigh.. and here I sit, yet again, with neither a logic analyzer nor a
decent digital scope. Unless something comes up, looks like I'll have to do
it the hard way, as usual - heh.
At least the machine doesn't have a totally scrambled brain, with the
correct CPU - so it will be easier to work through things, as I can at
least partially communicate with the hardware if needed. Well, except for
the lack of bootable media..
Anyone have a spare Z-80? Or some bootable media for the Osborne 1? I have
a few CP/M machines here, but I don't think any of them can write media for
the Osborne. Even so, I'd need a way to get the Oz disk images to the
machine of choice.. and that's another huge hurdle.
Help a brother out.. I need some bootstrap media!! ;-)
On Mon, Aug 17, 2015 at 12:13 AM, tony duell <ard at p850ug1.demon.co.uk>
wrote:
[Replacement Z80 in an Osborne]
> What I did learn is that Z-80 were made in CMOS versions, and the Z84C
is
one.
So what did I most likely do, here? Hose the CPU for sure? Collateral
damage on the board? Both / Neither?
Most likely neither (unless you put the CPU in the wrong way round or
zapped
something with static -- CMOS _and_ NMOS parts can be damaged that way).
If the CPU is fast enough for the clock speed in that machine then most
likely
a CMOS one will work without problems.
My guess is that the missing CPU was not the only fault. You now have a
good
CPU but problems elsewhere (clock, ROM, RAM, support logic...). Time to
grab
the logic analyser :-)
-tony