Filling in a Colourful Corner

I delve back into enough old computer systems that I do seem to let them lie fallow and then return to dig deeper. A big part of this depends on contributions made by other people, though, whether in the form of scanned documents or emulator programs. Pushing past the early 1980s, three different emulator programs for the Macintosh can get me to the end of the 1990s. One of the jumps between them is a bit bigger than the other, though, and it just so happened one single thing fell into that space to get my attention.
( A gradual process )