From: Marco Mailand (Newton_at_spymac.com)
Date: Tue Mar 09 2004 - 11:31:14 PST
"Eric Engle" wrote @ 9.3.2004 20:00 Uhr / <engleerica_at_yahoo.com>:
> <naive>How does one build an emulator?</naive> I would *love to have a fat mac
> emulated on my newt!
In general the hosting platform which runs the emulator software should have
at least a similar or better hardware like the emulated platform. From the
software viewpoint it is very helpful if the host's operating system has
comparable functionality as the emulated platform. About 15 years ago I
wrote a quick and dirty hack of a CP/M emulator for a Z80 computer with a
very simple EPROM burned monitor program. This emulator could process kbd
input and character output to the screen as well as cassette reading and
writing instead of floppy disk access. All what we had to do now was to get
CP/M programs, and I mean the compiled .com files from floppy onto the
cassette tape and modify it a bit with an HEX editor. We were very
successful with Prolog, a simple artificial intelligence programming
language at this time because it needed only 5 system calls.
I have to admit that we had the source code of the monitor system and a very
good documentation of the call 5h functionality of CP/M. With that
information it was really simple to write the emulator within a few hours
and it was only very few assembler lines, because most code functionality
was already well functioning in the monitor program. This was a nice time...
Not like today where we're helplessly exposed to the will of the software
giant(s).
Marco
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