I didn't know if the processor was still working after all this time on a disintegrating piece of antistatic foam so I wired up the simplest possible test circuit on a solderless breadboard.
Just the CPU plus a 100nF cap and the crystal with its 20pF load caps is required. And three 1K resistors that pulls up the lower three bits of data bus to force the baudrate to be set to 300 baud.
It's hooked up to a Adafruit FTDI adapter which also supplies the 5 volts power for it.
It seems like it works rather well as can be seen on the terminal above. It complains about a syntax error at line 24950, but I guess that is because the BASIC firmware gets confused when databus is flowing while it probing the memory ranges. At least I hope it is so or else the BASIC ROM has succumbed to bitrot over the years. :-(