I'm running the multicore SD card system on a Raspberry Pi 3.
This looks a lot like this bug
https://github.com/simh/simh/issues/815
If you are familiar with software development you could try to apply the patch yourself and rebuild.
(P.S.: I'm referencing the "old" simh repo so I can ppoint at this specific bug, but note that the Open SIMH project is now hosted here: https://github.com/open-simh )
PiDP-8/I release:id[280c662a13] [pi3b] [ils] [stdpcb] [gpio] [rt]
PDP-8 simulator V4.0-0 Current git commit id: 2f66e74c
Loading OS/8 from the RK05 cartridge disk...
PiDP-8/I release:id[280c662a13] - OS/8 V3D - KBM V3Q - CCL V1F
Configured by pidp8i@raspberrypi on 2021.02.15 at 03:51:25 GMT
If I run ps -u in another window I get this:USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
pidp8i 1305 0.0 0.3 8272 3548 pts/3 Ss+ Oct14 0:00 /bin/bash
pidp8i 1309 0.0 0.3 8272 3480 pts/4 Ss+ Oct14 0:00 /bin/bash
pidp8i 12304 0.0 0.3 8360 3524 pts/0 Ss 16:40 0:00 -bash
pidp8i 12358 141 0.2 13532 2424 pts/1 Rsl+ 16:40 10:36 /opt/pidp8i/bin/pidp8i-sim /opt/pidp8i/share/boot/0.script
pidp8i 12373 0.0 0.2 8000 2332 pts/0 S+ 16:40 0:00 screen -r -S pidp8i
pidp8i 12441 0.1 0.3 8360 3524 pts/2 Ss 16:45 0:00 -bash
pidp8i 12456 0.0 0.2 9788 2512 pts/2 R+ 16:48 0:00 ps -u
The figure for pidp8i-sim - 141% seems very high - the simulation is sitting idle at the OS/8 command prompt (dot).
ps -aux shows almost every other process is idle or consuming very little cpu.
After tweaking 0.script and restarting the emulation, show throttle says:
sim> show throttle
Throttle: 333 kiloinstructions
Throttling by sleeping for: 1 ms every 346 instructions
sim>
Andrew
The figure for pidp8i-sim - 141% seems very high - the simulation is sitting idle at the OS/8 command prompt (dot).