[CCTECH] any ISIS info out there?

From: Derek Peschel <dpeschel_at_eskimo.com>
Date: Mon Jun 24 16:24:23 2002

> I used ISIS-II extensively in its heyday. Today I have a few Intel MDS
> (Microcomputer Development Systems) that run ISIS-II along with the
> ICE80 (In-Circuit Emulator...quite a bit more powerful than a
> simulator), UPM, PL/M-80, and all the other development

Does ICE80 interface with a real ICE, then? I thought it might have been
marketing-speak similar to SoftICE.

> BTW, I'm not sure why you say that diskette formatting was more
> complicated. ISIS-II used a different file structure than CP/M, but it
> wasn't all that much more complicated, as I recall. The formats for

I was talking about the procedure to format disks, not the design of
the disk format. You can't format a nonsystem disk and then turn it
into a system disk later. The procedure for a one-drive system is
especially complicated.

BTW I like the idea of the "magic files" (ISIS.DIR and its relatives)
but I don't see why they have a special "format" attribute in the directory.
Doesn't the kernel recognize them by name already?

> files was more structured with object module files having identifiers
> embedded in them rather than just being a stream of binary that was
> assumed to be loaded at 100H and contiguous from there. You see, Intel

That relates to one of the flaws in CP/M that I mentioned. DRI assumed
you would be doing your own assembly and would know your own memory size,
so there's no portable way (that I know of) to find the locations of the
CCP, BIOS, and BDOS.

With the MDS you can find the size of the first contiguous block of RAM.
Unfortunately (I didn't realize this until I read the user guide) the
_starting_ address of your program could vary if the number of buffers
is different, so finding the end of free memory isn't as useful as it
could be. I suppose you could reLOCATE your program though.

The other flaw in CP/M is that the "change disk" and "reboot" functions
are inseparable. ISIS doesn't need to be told when a disk changes but
it does seem to have the same reliance on rebooting.

> the MDS's and all their programming tools. If you have some specific
> questions, maybe I can help. Also, you have a wealth of other sources
> here in Tony Duell and Joe Rigdon, and others I'm sure.

OK, you asked for it...

Do you know how much ISIS was tied to the IBM 3740 disk geometry?

What exactly is the purpose of all that switch-flipping at boot time?

Did anyone ever replace the text editor with a CRT-oriented one?

Did Intel publish the source code to any part of the system?

-- Derek
Received on Mon Jun 24 2002 - 16:24:23 BST