kolloid
New Member
I worked with a PDP-12 that was installed in the faculty of Medicine in Montevideo, Uruguay, where I lived at the time. Around 1969, a 8K machine with two linctapes. After working with a IBM 360 with punched cards, it was fascinating being able to edit text interactively on a screen!
First we used a version of LAP-6, a OS written originally for the LINC. Later we changed to OS/12, a variant of OS/8 for the -12.
Years after that, after having moved to Spain, I decided to write an emulator, since there seemed to be none. But I wrote it from scratch. At that time, some 15 years ago, simh was not up to emulating the -12.
I also got a LAP6 listing from the Computer Museum in California, typed the sources then wrote a simple assembler in Python, and now have the LAP6 essentially working in the simulator.
Not everything works, though. LAP6 is small but complex with overlays, instructions that are overwritten and so on. Also the sources are very sparsely commented.
The problem is that I don't have access to a real machine, so I can't compare results. But the simulator runs the maindecs well, I wrote a minimal PDP8 code to test the -8 instructions since LAP6 doesn't use -8 instructions.
What runs now is the CPU, with the whole set of instructions, the panel lights, the panel switches (albeit in a sui generis fashion), the VR12 screen, the A/D converters, the variable speed of the original machine. Also a debugging infrastructure ...
Alex, thanks for your welcome!
Antique Kid, the emulator is written in C++ using the Qt library. The screen updating is too slow, so I'm thinking about rewriting that in SDL2 or something. I have been looking at the screen code in simh, perhaps that could be useful.
Djg, I also don't have any hardware for reading those tapes. I know that there are/is some -12 here in Europe, will have to look around...
First we used a version of LAP-6, a OS written originally for the LINC. Later we changed to OS/12, a variant of OS/8 for the -12.
Years after that, after having moved to Spain, I decided to write an emulator, since there seemed to be none. But I wrote it from scratch. At that time, some 15 years ago, simh was not up to emulating the -12.
I also got a LAP6 listing from the Computer Museum in California, typed the sources then wrote a simple assembler in Python, and now have the LAP6 essentially working in the simulator.
Not everything works, though. LAP6 is small but complex with overlays, instructions that are overwritten and so on. Also the sources are very sparsely commented.
The problem is that I don't have access to a real machine, so I can't compare results. But the simulator runs the maindecs well, I wrote a minimal PDP8 code to test the -8 instructions since LAP6 doesn't use -8 instructions.
What runs now is the CPU, with the whole set of instructions, the panel lights, the panel switches (albeit in a sui generis fashion), the VR12 screen, the A/D converters, the variable speed of the original machine. Also a debugging infrastructure ...
Alex, thanks for your welcome!
Antique Kid, the emulator is written in C++ using the Qt library. The screen updating is too slow, so I'm thinking about rewriting that in SDL2 or something. I have been looking at the screen code in simh, perhaps that could be useful.
Djg, I also don't have any hardware for reading those tapes. I know that there are/is some -12 here in Europe, will have to look around...
