I have the professional diagnostic chip-set and plug-ins for a C64 if anybody is interested - all in their original box. On the hierarchical list of dinosaurs there should have been the Lucas NASCOM (Zilog Z80 based machine that I built from kit having first to fault-find and resolve PCB faults first), the Commodore Vic 20 which was the ancestor of the C64, and the Commodore Plus-4 which had software preloaded and accessible by soft-key (and a better machine in my opinion but marketing of the C64 pushed this aside in preference of the gaming community). I built a modem and used a Commodore 64, in conjunction with a 145MHz transmitter, to connect to local BBS on the ham packet radio network in the early days. There was GEOS a 'Graphics Environment Operating System', extra (massive at the time) plug in half-meg RAM packs and early internet connectivity. There were also hard-drives and faster chip-sets available from the small but very valid team of die-hard Commodore supporters. Fun times - gonna go SYS65535 now