ralphw@ius3.ius.cs.cmu.edu (Ralph Hyre) (02/17/89)
Is there anything that describes the programmer's and user's interface
to this beast?
Mainly to satisfy my curiosity, I want to understand how the system works
and compares with other multitasking/multiuser versions of operating systems
that run in an 8-bit environment. (I've also heard of a possibly competing
system called TurboDOS, but am not very familiar with it.)
Thanks for any pointers provided.
--
- Ralph W. Hyre, Jr.
Internet: ralphw@{ius{3,2,1}.,}cs.cmu.edu Phone:(412) CMU-BUGS
Amateur Packet Radio: N3FGW@W2XO, or c/o W3VC, CMU Radio Club, Pittsburgh, PA
"You can do what you want with my computer, but leave me alone!8-)"
-- rbloom@APG-EMH1.APG.ARMY.MIL (Robert Bloom AMCICP-IM 3775) (02/21/89)
MP/M is a multi-user version of CP/M v2.2. Each user gets their own 48k bank of ram, the upper 16k is the 'executive'. The single processor is switched between users by bank selecting. I don't know if CP/M itself must also squeeze in the 48k, giving each user their own copy of the os. There is a Osborne-Hill guide to CP/M and MP/M with all the system calls - maybe still in print, it (the book, not the os!) was very popular at the time. MP/M gave the user too little memory, a slower than normal processor (due to sharing it with other users), and very rudimentary file control (user numbers). Looked just like standard CP/M to the user, but with the user # in the prompt. I'm much more familiar with NorthStar's varient of MP/M called TSS/C - each user got 56k of Ram to hold a copy of CP/M and their programs, the upper 8k did nothing but switch the z80 between banks and manage the disk(s) and printer(s). There was also a 32k bank dedicated to the system. Worked well but slow. (Five [!] users on one 4mHz Z80 - what did I expect!) NorthStar (and I) replaced TSS/C with TurboDOS, a multi- *processor* system - giving each user a dedicated (z80 or 8086) processor w/Ram with one 'master' processor w/Ram for shared resources. Block diagram looks just like a LAN with all processors in one box. Both systems generally ran only on S100 boxes. Most s100 SBC's (Single-board computers) have TurboDOS drivers available. Bob (rbloom@apg-1.arpa) Bloom