The MP/M experiment - Page 1
Forum section: electronics / general

author: Just4Fun
author_rank: Contributor
timestamp: July 20, 2019, 07:44:36 am
content: This is a "crazy" experiment that I've done using my own HW, just because I was curious to see a MP/M system running in a "real" situation with 4 concurrent terminals/users.The FPGA board runs a VHDL Z80 Multicomp with MP/M 2.1, HD on SD and 4 serial ports (ported fromhereadding the needed modifications):One FPGA serial port (Serial 1) is connected to the STM32 MCU inside the board, and the STM32 runs a "sketch" to act as a serial-USB bridge. So the USB connector is used to power the board and also to connect the Serial 1 port of the Multicomp (inside the FPGA) to a terminal emulator (on a PC):Here the video:More info about the FPGA boardhere.

author: Ampera
author_rank: Super Contributor
timestamp: July 20, 2019, 02:18:42 pm
content: That poor Z80 (FPGA).I absolutely love this. I love the idea of timesharing computers. A bunch of terminals connected to just one big o'l userland, doing all sorts of stuff on huge monolithic equipment, all wrangled by some guy with the main terminal.

author: guenthert
author_rank: Frequent Contributor
timestamp: July 20, 2019, 06:06:50 pm
content: Quote from: Ampera on July 20, 2019, 02:18:42 pmThen I have good news for you: chances you have a "timesharing computer" already. In your phone or router, if not on the PC you typed the message above with. If not, for about $35 you can buy a Raspberry Pi which comes with a timesharing OS. Just connect your terminals.

author: Ampera
author_rank: Super Contributor
timestamp: July 20, 2019, 07:35:22 pm
content: Quote from: guenthert on July 20, 2019, 06:06:50 pmLol, if you mean do you run Unix (or perhaps Linux), yes, almost all my computers run something among those lines. My main server is even structured sort of like a timesharing server, and even has another user SSHing in every so often to run some stuff.The point being, it's not really the same as the classic implementations of timesharing systems. Of course I can make one, in essence I already have, but it doesn't have the same point or reason to exist as a genuine timesharing system, which has users, membership, things to do, admins, internal mail/chat, dial in connections, etc.

author: rrinker
author_rank: Super Contributor
timestamp: July 22, 2019, 06:57:58 pm
content: This is pretty cool. MP/M is something I've only read about (I ran CP/M on my TRS-80 as much as I did TRSDOS). Never saw it in operation before. My first exposure to something like this was Xenix on the TRS-80 Model 16/6000 - my friend and I hung out at the local computer center so much that they set us up with accounts to play around with the store demo system.My first job after college, one of the things I worked on was fixing a machine tool controlled by a PDP-11/23 with RSX-11. I had two terminals, so it was really neat watching the system time slice between my two sessions, all with I think a mere 4K words of memory. Been a long time but there was some sort of monitor utility that would how an updating view of the memory and cpu and what process was using what - on a VT100 CRT this would nicely refresh every few seconds, while my actual FORTRAN program controlling the machine tool ran on a DECWriter so I could get a hard copy output of the test results.I have a machine that can run CP/M, an old NEC PC8800, which also has the 16 bit card and can run MSDOS, but part of me wants to build a more pure Z80 system with simple terminals - though once I got it all up and running, I'm not sure what I'd do with it - which is the only thing stopping me.

author: duak
author_rank: Super Contributor
timestamp: July 27, 2019, 09:06:12 pm
content: A blast from the past! I remember getting MP/M running on my own home system. Never did much with it although I used CP/M for a few years after that.The last timeshare system I used was a VAX 11/780 in the early 80s. It was used for editing, software development, and general engineering processing. At 6 PM, what was normally a brisk, responsive system with 30-40 users would die because someone would start up some game program that did some ASCII graphic stuff on VT100s. VAX/VMS treated I/O and the associated process with high priority so everything else crawled while it serviced the game terminals. A compile that would ordinarily take a few seconds would take minutes if not more. The IT department bought some smart serial boards that offloaded the character I/O from the CPU and it started to run a whole bunch faster. In the interim, we found that ctrl-T on keyboard would show your process status and also escalate its priority so it would run quicker.

author: bd139
author_rank: Super Contributor
timestamp: July 27, 2019, 09:20:27 pm
content: Amazing stuff. Nice job. I have never seen MP/M working. I had some ancient experience with CP/M though in the distant past on RM 380Z at school. It really is just a multi user version of that which makes it more awesome.