Re: Zilog stopping Z80 production

On a sunny day (Sat, 27 Apr 2024 13:57:05 +0200) it happened Gerhard Hoffmann
<dk4xp@arcor.de> wrote in <v0ip6h$1tn2$1@solani.org>:

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

I used 5 1/4 inch floppies in Kaypro2 format
added a 256 kB RAM disk addressed by the Z80 I/O instuctions.
Added a 'copy floppy to ramdisk' command, and could run from there.
No seek and no r/w times times.
 https://panteltje.nl/panteltje/z80/system14/diagrams/index.html
scroll down to
 Ramdisk card:
 diagram part 1
 diagram part 2
 component layout
 timing waveforms
Wrote my own CP/M clone.