[comp.sys.m6809] RS-232 port: hardware or software?

davis@utx1.UUCP (Gary A. Davis) (07/22/87)

in article <500@otto.COM>, rex@otto.COM (Rex Jolliff) says:
> Posted: Sat Jul 18 08:34:07 1987
> 
> 
> I was thinking of buying a coco (2 or 3) and I was wondering if the rs-232
> port is all hardware or if any of it is implemented in software.
> 
>                                                             Rex.

The coco comes with a serial port with 4 pins (send, rcv, gnd, status). It is
implemented in software by waiting for ready, transmitting a bit and then
delaying based on a pokeable variable and finally back to waiting for ready.

I have no problem transmitting (to a printer) at 9600 with this port. Modem
communications which is bidirectional is limited to 300 with many terminal
emulators but some can hack 1200.

Optionally, a hardware port is available (I think it has been discontinued,
but they are still around) called a Deluxe RS232 Pack. It plugs into the rom
port or one of the (optional) multi-pak ports. I think this allows upto
19.2k. Many people get both the multi-pak and the RS232 pack and plug the
modem into it leaving the serial port for the printer.

Gary
-- 
  Gary A. Davis
  Racal-Milgo, P.O. Box 407044, Fort Lauderdale, Fl 33340, (305) 476-4393

  ihnp4!allegra!novavax!utx1!davis