info-mac@uw-beaver (info-mac) (07/26/84)
From: gvax.kevin@Cornell.ARPA (Kevin Karplus) I've got a student building an A/D converter to hook up to one of the serial ports. To get sufficient speed, we have to provide an external clock. I've got documentation on the 8530 chip, so can probably figure out the right settings of the chip. What I need to know are the addresses to read and write. The only thing I could find in Inside MacIntosh was: "the 8530 SCC (Serial Communications Controller) $90000-$9FFFFF" That helps somewhat. There are four addresses that the chip should respond to (A/B choice and Data/Control choice). Can anybody tell me which of the low order 20 bits are used for this? Also, I can't remember which port is A and which B. Is A the modem port? Thanks, Kevin Karplus