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From: Gerhard Hoffmann <dk4xp@arcor.de>
Newsgroups: sci.electronics.design
Subject: Re: Zilog stopping Z80 production
Date: Sat, 27 Apr 2024 13:57:05 +0200
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Am 27.04.24 um 12:39 schrieb albert@spenarnc.xs4all.nl:

> Motorola was much better in this respect. Peripherals are accessed
> by handshake. So you could  put a longer delay iff the peripherals
> are slow.
> 
> I remember spending 2000 guilders in around 1980 for 16 K ram
> for my Z80.
> Just to discover that code in this ram couldn't run, because the
> Z80 was too slow. Only useable for data.

The other way around. The RAM cycle time was too slow for the
Z80 because of the DRAM refresh cycle after the instruction fetch.
And there was a /wait input on pin 24 if your bus logic was
unable to keep up with the Z80. Looks like handshake for me.

My first 64K*1 DRAMs did cost DM 64,00 each - which was quite a
sensation (NEC or Hitachi). And of course, my system got
the the first usable 8" DSDD floppy drives and ran CP/M.
I'm pretty sure that the instructions were in DRAM.
There was no ROM after booting at all.

I did the CP/M port with a friend. It later turned out that
the Altos computer was near identical, just patching the
I/O addresses would have been enough.
Later I even got a 1MB RAM floppy, powered by 8086.
(really to do a paid CP/M-86 port  :-)

regards, Gerhard