Re: Using modem on IIGS

[dempson@actrix.gen.nz (David Empson)]

David Cross <dcross1@nospam.home.com> wrote:

> I heard once a very vague rumor that one could set the //gs's serial port
> to run at 115200 bps, but I have NEVER found a way to confirm this or even
> test it out.

I'm not aware of any way to do this.  It would require halving the
crystal frequency somehow, and changing the clock mode to bypass the
baud rate generator.  Most Macs offer this speed, but only because of
external hardware that changes the clock speed.  (Earlier machines only
support speeds up to 57600 and 230400.)

It could be done with an external box that produces a different clock
frequency (like with the Apple MIDI interface), but you would lose the
input flow control signal, which makes it impractical for a high speed
modem.

It is possible to get 230400 bps for asynchronous communication by
changing the clock mode, but I'm not aware of any software that does
this.  This would work better than the Turbo ASB by virtue of the three
byte receive buffer in the Z8530 SCC chip, but would need an accelerated
machine to keep up.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand