edward@ga.ecn.purdue.edu (Edward L Haletky) (12/17/87)
Netlanders,
I am trying to write a multitasking shell for am IBM PC, either as a
replacement for the braindead command.com or as a cooperating system. I would
like it as close to csh as much as possible. The processes will have to be
preemptive. This implies that in order to put a job in the background I need
to make an estimate of how much memory is needed (data, program, etc). How
would I go about finding this out?
I would like to continue adding background jobs until memory is gone. The
system would be prioritized. I assume I am approaching this correctly. In
order to switch processes I believe I would need to keep a record of all
the registers and necessary interupts as well as the current memory location
of the executing code. The main problem I can think of is in keeping track
of what memory is available for each process to call. Any help would be
appreciated. (either '286, '386, or 8088 cpu`s).
Thanks in advance:
===================================== ^ =================================
Edward L. Haletky |E |o| U| "To race against the sky..."
Usenet: ~!pur-ee!edward |L ^/| |\^ S| "The world of the
Arpa: edward@ga.ecn.purdue.edu |H / | | \ A| immagination is boundless."
=====================================/__-|-__\=================================simrin@mis.ucsf.edu (Steve Simrin) (12/19/87)
How about OS/2?
wtm@neoucom.UUCP (Bill Mayhew) (12/22/87)
>How about OS/2?
For '386 based systems, PC/MOS doesn't look too bad. The newest
release seems to be reasonably un-buggy. Of course, this requires
a '386 based system. The advantage is it is a lot cheaper than
OS/2, and it does multitask present day DOS applications. There
was supposed to be an MMU board to run PC/MOS on '286 based
systems; I don't know if the MMU has condensed from the vaporware
stage yet.
The AT&T 6300+ with Locus' Simultask is pretty decent. I've seen a
6300+ run up to 7 DOS windows, not all of which, though, were doing
really "hard" work.
Deskview 2.01 is another possiblity. It's probably the cheapest
solution. The previous versions of Deskview were too buggy to be
worthwhile. 2.01 still has some limitiations (which have been
already hashed over on the Net). Depends on how demanding your
application is and how flexible you are.
Season's Greetings,
--Billtim@cit-vax.Caltech.Edu (Timothy L. Kay) (12/23/87)
In article <871@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: > >>How about OS/2? > >For '386 based systems, PC/MOS doesn't look too bad. The newest >release seems to be reasonably un-buggy. Of course, this requires >a '386 based system. The advantage is it is a lot cheaper than >OS/2, and it does multitask present day DOS applications. There >was supposed to be an MMU board to run PC/MOS on '286 based >systems; I don't know if the MMU has condensed from the vaporware >stage yet. Funny you should mention a MMU for 80286 machines. I was just looking through this month's _Los Angeles Computer Currents_. A full page ad on page 29 starts with EXTEND DOS RAM TO 960K. It then goes on to describe a memory management board that lists for $399. They claim that this board allows you to do a zillion things, including running PC/MOS on your 80286. I just called them. My first question was, "Does it really work?" His answer was an emphatic yes. "So why aren't we seeing national advertising on this thing?" He said that we would be seeing it soon. Quite frankly, I don't see why somebody would spend $400 on this when you could spend about $1000 on a 80386 motherboard. It would also happen to run twice as fast. And it would do a much better job of multitasking. The name of the company is Compatible Computer Centers, Inc. 818-704-4955. If you have questions, you might just forward the questions to me. I am interested, and it is a local call for me. Then I'll send you mail back, or post it if there is enough interest. Tim