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 . <drlegen...@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 <a...@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 > > >
