midkiff@portia.Stanford.EDU (Neil Midkiff) (07/20/90)
On the Mac SE and II, pin 7 of the serial ports is the "general-purpose input" or GPi, connected to the serial controller's Data Carrier Detect input for that port. The DCD input to the SCC can be polled by software or used to generate an interrupt. (Above summarized from p. 362 of _Guide to the Mac Family Hardware, 2nd edition_.) My question is HOW? Inside Mac volumes 4 and 5 are apparently silent on the matter, and since this input didn't exist on the Plus or before, it can't be in an earlier volume. (At least I couldn't find it!) -Neil
russotto@eng.umd.edu (Matthew T. Russotto) (07/23/90)
Reading GPi can only be done by reading the SCC directly at SCCRBase plus aCtl for port a or bCtl for port B. Sorry, I don't know the bit number for enabling DCD interrupts or for reading DCD. HEY APPLE: How about a trap for these things. And I DONT mean the Comm Toolbox! Having to purchase parts of the system separately is for MicroSloth and IBM. -- Matthew T. Russotto russotto@eng.umd.edu russotto@wam.umd.edu ][, ][+, ///, ///+, //e, //c, IIGS, //c+ --- Any questions? Hey! Bush has NO LIPS!