Recently my grandmother has retired her old 80's Janome MC6000 for a modern Brother somethingsomething modern equivalent. The MC6000 is mechanically starting to wear out and adjustments are getting little finicky to say the least, but I thought I would try my hand at giving it a good cleaning and lub once again along with maybe even backing up the ROM chips if it had any for good measure. It still works. I'm just looking at doing a partial restore as I'm a fan of 80's computer tech; aren't we all?
Anyways, while the yellowing plastics are soaking in a retrobrite solution I thought I would go ahead and start looking at the electronics. I've managed to figure out that the four larger NEC branded chips are two programmable microcontrollers, one PROM, and an IO expander. I've found the datasheet for the 8049, however, I cannot seem to find any more information on the other three chips other than what they are. No pinnouts, no nothing.
Any thoughts?