compucolor

Vintage Computer Festival wrote: ... I didn't see any smoke. The previous owner reported it, so it was just speculation on my part that it was dust cooking off the CRT neck. A very common problem reported is that the switching power supply sometimes wouldn't start oscillating and it would result in a cooked machine. I have to respect both, for different reasons. The compucolor design (given the fact that the RS-232 chip was already there) cost them one jellybean chip -- they mux/demux the data to the RS-232 port or the disk drive using a few sections of a tristate buffer. The apple II design by comparison was 10x more complicated. The apple II design also had super critical timing requirements of the driver code but the compucolor design didn't. On the flip side, the apple design had better density and was incredibly flexible. So I respect the compucolor for minimalism and the apple design on esthetics. It has been reported that originally the compulor was designed to store to an 8-track cart, but then they ECO'd it to drive a floppy disk instead. The disk allocation is very simple and perhaps derives from its original tape cart implementation. Files are contiguously allocated on the disk and files are kept packed. Files can only be added to the end and if you delete a file in the middle, all the later files get shuffled down. And in order to make it go faster, they use the 4K of video RAM to buffer multiple sectors during the shuffling.