I think I was about 12 or 13 when I first set eyes on a SC/MP system, a MK14 I think it was, back in to 70s when a friend of mine had one. Although I was already programming my own hand-wired vero-boarded (non-SC/MP) micro in machine code (no assembler then, we just coded up the hex directly onto paper from our heads), I couldn't figure out how to get the MK14 to do anything. ISTR you had to multiplex the 7 segment display in software, which in itself was a barrier to doing anything at all with it as there was a fair amount of complexity involved to do the most basic thing. I wonder how many of those ended up in drawers?
UHF modulators were the voodoo of the day, nobody knew how they worked, but the black and white ones looked really simple inside. The colour ones were on a different level though. Astec used to make the ones used in the UK, they had that market sewn up.
Beautiful Teletype by the way, I was expecting to see them on ebay when I looked last night, nothing to be had other than parts, it looks like they must be serious collector's items now.