I remember seeing a computer with 24-bit graphics at a computer store in the mid-1980s. It was not a normal PC with a high-end graphics board installed; the graphics came standard, possibly with three 8-bit graphics boards pre-installed. In my memory this was a DEC Rainbow, but I looked that up, and that seems to have been am unremarkable business machine with just 1-bit/pixel. Now I am thinking it may have been a high-end TI 808x machine aimed at the professional market (unlike the TI 99/4).
As I remember, this machine did not last very long. There was very little software available supporting 24-bit graphics on PCs, and, while an MSDOS machine, it was not considered a PC Clone. Does anyone else remember such a thing? What was it?