Keeping up with 19200 baud

[Stuart Lynne]

In article <568 at panix.UUCP> alexis at panix.UUCP (Alexis Rosen) writes:
>
>This is not my field of expertise, but I believe that the Mac's built-in
>serial ports can't begin to cope with 19.2kbps because they get an interrupt
>for every byte. If so, either your statistics are wrong, or you're using a
>serial card.
>
>So: Am I wrong? If not, are you? If not, what card are you using?
>

The Mac's serial ports work fine for keeping up with 19.2kbps. Most terminal
emulators have some problems do to screen updates etc. Using appropriate
load shedding techniques you can fairly easily have a terminal emulator that 
keeps up to 19.2kbps without flow control. I have a desk accessory that does it.
Worked well on a 128kb Mac, was only about 8kb in size, and was written in C
(well with some inline's).

Basically you need to setup a large FIFO buffer for serial data, get in
large chunks vs. one char per call, only update screen display for every few
lines ... just your basic optimizing techniques. 

Another data point, Appletalk (or whatever they are calling it these day's)
run's at 240(?)kbps without problems.


-- 
Stuart.Lynne at wimsey.bc.ca ubc-cs!van-bc!sl 604-937-7532(voice) 604-939-4768(fax)