5 May
1999
5 May
'99
1:55 a.m.
I'm trying to put together a Prom Programming
station based on the iPDS
(Intel's Isis luggable) computer. I've managed to locate the OS, and some
applications but am still in need of the Prom programming software. I
think it was titled 'IPPS'.
Sorry, I can't help you. I was actually going to ask _you_ some questions.
You may want to try Intel's site, though. They have a small amount of ISIS
stuff there (an emulator and maybe some other things). It's very
disorganized -- you have to use the search function. Intel doesn't seem to
care about such ancient history.
Do you have any documentation for ISIS? I tried playing with the emulator
and couldn't manage to do anything. I'm mainly wondering what features ISIS
provides as an operating system and what its commands are.
It's also very enlightening to compare ISIS to CP/M. Although CP/M was
designed with an external interface that looked sort of like DEC's PDP-11
OSs, internally CP/M seems to have been inspired by ISIS to some degree. I
forget why I came to that conclusion (because I don't have the appropriate
articles in front of me) but I know the register conventions were similar
and I think the modular construction, memory layout, etc., may have been
similar too.
The funny thing is, CP/M has some silly flaws that shouldn't have happened,
because ISIS doesn't have those flaws! Two especially come to mind:
- No supported way to tell where in memory the parts of CP/M are.
DRI's approach of "assemble CP/M for your particular system" is
only workable for hobbyists that build and program their own
machines and never use anyone else's binaries. I think ISIS has
a system call that gives you the current memory layout.
- Not necessarily easy to get to the non-file parts of a disk
(the boot tracks, directory blocks, etc.) I've heard ISIS had
a number of fake "files" for the non-file parts of a disk, which
made disk hacking a lot easier.
- Warm boots. I never understood why the warm boot in CP/M was
combined with the routines to reread a disk directory. They are
not the same thing. Changing disks is such a nuisance. Oddly,
CP/M keeps enough information in memory to tell it that the
directory is invalid... so why can't it just read the new
disk instead of giving an error? I forget if ISIS solved this
problem as well.
Of course CP/M eventually got some features that I doubt ISIS ever had
(longer file names, network and graphics support, three different hardware
platforms, more software).
-- Derek