On 2017-Oct-27, at 10:27 AM, Paul Koning via cctalk wrote: > So it's a question of what you're after. If you want to run the software, or > teach the machine at the programmer level, SIMH or equivalent is quite > adequate. If you want to teach FPGA skills, an FPGA behavioral model > emulation is a good project, especially for a small machine like a PDP-8. As > for the gate level model, I'm not sure what argument to make for that other > than "paul is a bit crazy" and "because the data exists to do it". :-)
I would add that gate/logic level simulations in some instances can be useful if you have to understand and repair the original hardware. Back in the 90s I was attempting to repair a 60s-era SSI-based calculator, I reverse-engineered it but was still stuck with issues of access to the PC boards, understanding the design, having to hack up the PCB traces or unsolder (unobtainable) ICs. I resorted to writing a logic simulator (in a high-level scripting language) and entering the 'net list' of the reverse-engineered logic to produce a gate-level simulation. I could then play around with the simulator, slow the clock to observable rates, monitor any and multiple points, break connections, force logic levels, eventually to obtain the same fault as the real hardware.
