If you pulled the plug and then reconnected the power, the operating system picked up where it left off. This was a system with core memory that didn't need power to retain memory. The RSX light pattern starts from each side of the LEDs and moves to the center where it then explodes outward. In the early 1980s, I saw the RSX pattern on a PDP-11/70 at a DEC office in Chicago where I was taking the RSX operating system internals course. My goal was to run RSX11M+ on an emulator and have the reanimated display exhibit the idle light pattern that RSX systems produced on PDP-11s. This was a smaller front print PDP-11/70 that fit in two tall 19 inch racks. I bought a DECsystem 570 front panel on ebay. First I’d like to provide a bit of background on my project that Jörg Hoppe made possible with his modified Simh and the Blinkenbus technology he and his colleagues have developed.
