The idea behind the HP 64000 was brilliant, and way ahead of its time, in my opinion... Basically you have a "debugee" CPU/computer system and a second "debugg

The idea behind the HP 64000 was brilliant, and way ahead of its time, in my opinion... Basically you have a "debugee" CPU/computer system and a second "debugger" computer on the same motherboard or integrated circuit backplane... An on-board signal analyzer (also on the same motherboard or backplane) is connected to all of the signal paths of the debugee computer system -- which in turn is connected to the debugger computer. It's sort of like having two computers on the same motherboard/backplane -- but one can monitor/trace/log/breakpoint/debug -- absolutely all of the I/O of the second one -- at the electrical/hardware/signal level. Which is no small task... If I were designing future computers, and money/space limitations were no object -- I'd design them all around this model. Why? Because it allows debugging/transparency of the debugee machine at a level that just can't be obtained by running a software debugger on the debug machine! (Running a software debugger on a debug machine destroys that machine's absolute system state and timings -- it may work and it may be 99.9% accurate -- but it will never be 100%. Not touching but merely observing a second system via a non-interfering signal analyzer -- does not interfere with anything related to the debuged computer's system state, and is theoretically 100% perfectly accurate...) Anyway, it's a brilliant idea -- way before its time!