Re: Read full 8-bit character from serial port?

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

Ron Kneusel <oneelkruns@hotmail.com> wrote:

> I'm using an Apple IIgs to read/write characters while debugging a
> program on my PC.  I can send a full 8-bit character easily enough but
> my attempts to read a full 8-bit character have failed so far.  The
> high-bit is always set no matter what.
> 
> I've tried using IN#2 and the monitor routine at $FD0C.  I've also
> tried using the SSC routine at $C205 with the same result.  For output
> I'm using PR#2 and $FDED which seems to send a full 8-bit character.
> 
> So, any ideas on how to read a full 8-bit character from assembly?

It should be possible to get 8-bit data using the IIgs firwmare. It may
be necessary to send some commands to the firmware to enable 8-bit
character delivery, and/or put it into transparent mode.

It might also be necessary to use the Pascal 1.1 firmware entry points
rather than the BASIC ones. This is a little more complex as you have to
use self-modifying code with the routine address patched in from a
lookup table somewhere around $C211.

I don't have my manuals accessible so I can't fill in the details. If
someone has an online copy of the IIgs Firmware Reference, the necessary
info should be in there.

-- 
David Empson
dempson@actrix.gen.nz