On a sunny day (Mon, 23 Apr 2018 16:44:09 +0200) it happened "A. Dumas"
 wrote in
:

>On 23/04/2018 15:56, Jan Panteltje wrote:
>> For assembler I had '8080-Z80 Assembly Language-Techniques For
>> Improved Programming" by professor Miller,
>
>I had https://ewoud.home.xs4all.nl/misc/machinecode.pdf (15 MB)

Cute, with all those little pictures.
I see they mention ZX81, that had a nice BASIC.
I added some memory to my ZX81, and an EPROM programmer board,
then wrote a CP/M clone and floppy interface so I could run Kaypro II format
CP/M programs from the computer club on it from floppy.
Then added a RAM disk and a whole lot of other cards, finally took the ZX81
out of circuit and added a separate Z80 processor card, and a IBM AT keyboard.
Wrote the driver for that keyboard too.
Now it was a full CP/M system, and due to the I/O mapped RAM disk faster than
the early IBM PCs.
Would load the whole 256 kB Kaypro format floppy into ramdisk, then no more
seek rrr rrr rrr and read / write  times.
When finished write everything back to floppy.
Never understood why nobody else did it that way.
Had a C compiler C80? running on it from Software Toolworks IIRC.

Lots of evenings, some holidays coding, wrote a Z80 disassembler too,
people still seem to use it from emails I get:
 http://panteltje.com/panteltje/z80/index.html
 http://panteltje.com/panteltje/z80/system14/system14.doc.txt
 http://panteltje.com/panteltje/z80/system14/diagrams/index.html

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