Re: More on the Faster Super Serial Card

[David.Empson@bbs.actrix.gen.nz]

In article <3589@carroll1.cc.edu> acct069@carroll1.cc.edu (Ron) writes:
> 
> 2) This does not have anything to do with the //gs built-in serial port.
> Maybe after this project is complete, I'll look into the //gs serial
> hardware to see what can be done.

The IIgs can accept a clock input (at RS-232 levels) from an external
device.  This replaces the normal function of the HSHK IN line, and
requires reprogramming some registers of the Z8530 SCC.  I believe the
maximum frequency that can be input is 4 MHz.

The IIgs uses a 3.6864 MHz crystal.  For asynchronous transmission,
this is divided by at least 64, giving a maximum data rate of 57600
bps.  This can be done with no hardware modifications, just a simple
change to the contents of a couple of registers.

The maximum data rate for synchronous transmission (e.g. AppleTalk) is
230400 bps.
-- 
David Empson

Internet: David.Empson@bbs.actrix.gen.nz    EMPSON_D@kosmos.wcc.govt.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand