I am only just getting started with SIMH, so perhaps I'm getting a bit ahead of myself, but here goes...
A classic graphics system of the early 1970s was the Imlac PDS-1. The display was a vector-stroke type, driven by a display list in memory and continuously refreshed. It had a CPU for communicating with a host (typically a PDP-10) and local calculations, and a GPU (Graphics Processing Unit) for executing the elements of the graphics display list, both running out of the same memory. Peripherals were generally limited to a serial line, the light pen, and a single switch (often a foot switch). The CPU looked very much like a 16-bit PDP-8, which should be almost trivial to simulate. The GPU would be a bit trickier, as it would have to draw lines on the host's display. The real problem, as I see it, would be how to have *two* simulated computers operating simultaneously from the same memory. I seem to recall a discussion on this list about how that would be difficult, but can't recall the details. Does anyone have any ideas on how this might be done? I would be interested in doing it, as I just happen to have an Imlac PDS-1D here, and would like have a simulator before I sell the actual unit. I also have a complete set of documentation with all schematics, plus some software. A second system of interest is the CDC 6600. Again, the problem as I see it is combination of a CPU and multiple PPUs (Peripheral Processing Units). It also used ones-complement arithmetic, which might cause difficulties. Does anyone have any thoughts on these matters? Alan Frisbie _______________________________________________ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh