Z80 / Z84C Swap (Doh!)

drlegendre . drlegendre at gmail.com
Sun Aug 16 19:20:38 CDT 2015

As the proud owner of an NtM Osborne 1 computer, courtesy of our own Jules
Richardson (and another list member), I made no delay in opening the case
to install a missing CPU. Jules was kind enough to let me know about the
missing part prior to handing the old girl over to me.

I'm sure you've already figured out what happened - unaware that the Z84C
series was CMOS, that's what went into the Osborne's CPU socket.

The machine came to life with a garbage display and howling on-board
beeper. Tried resetting it a few times, all I got was more and different
noise & garbage. That's when I shut down and did some reading - initially,
I thought it might be a clock speed issue - sometimes 'faster' chips won't
run at slower clock rates.

What I did learn is that Z-80 were made in CMOS versions, and the Z84C is

So what did I most likely do, here? Hose the CPU for sure? Collateral
damage on the board? Both / Neither?

As ever, it's what you don't get, that gets you.

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