kadickey@phoenix.Princeton.EDU (Kent Andrew Dickey) (07/12/89)
I am working on a program that needs to use the GS's modem port--but
I don't want to use the built in firmware. I want to leave slot 2
open for another card, which is only possible if I write directly
to the port's registers at $C038 and $C03A. Everything works great--
but I don't have any manuals describing what each BIT in the SCC 8530's
registers mean. The //gs Hardware Reference Manual briefly states
what each register signifies--but not explaining what each bit does.
I have a driver working but I don't know how to properly initialize
some registers, and I don't see how to turn interrupts on for when
the transmit register is empty.
I have some code from other programs which use the port directly--
so I've figured out the baud-rate generator constants, etc.--but I
could use a more complete list. Also, some registers seem to be set,
and then changed again several milliseconds later to a slightly
different value in the routine I am examining--is this necessary?
If so, for what registers?
If anyone even has an address/phone number at which to contact the
Zilog Corp. to get their technical manual for the SCC8530, I'd
appreciate it.
Also, as a more general modem-related question: What's the best way
to check for carrier loss? Waiting for the words 'NO CARRIER' all the
time seems like a bad idea--is there some signal from the modem I can
check for? My modem doesn't seem to change the state of the DCD line,
but perhaps I am trying to access it improperly (I am guessing from
the code I'm looking at).
Any help/information/pointers in the right direction would be
appreciated.
Kent Dickey
kadickey@phoenix.Princeton.Edu
kadickey@PUCC.Bitnet