Re: ADTPro beta - now with native IIgs serial support

["Michael J. Mahon" <mjmahon@aol.com>]

schmidtd wrote:
> PZ wrote:
>
> > Keep up the good work.  Does this change bump up the max GS port
> > transfer speed from 19,200bps to 57,600bps by any chance?
>
>
> Not yet.  My SCC init routine is purposefully written to talk to the
> SCC registers directly - bypassing the CtrlA-1-5-B business.  (I groked
> the Darwin source code for insights into SCC programming...)
> http://darwinsource.opendarwin.org/Current/AppleSCCSerial-130.4.0/
>
> I can set up the timing constants up to 57,600, but I'm not sure the
> firmware can keep up at anything past 19,200.  I have example code from
> a BBS, and of course we have Apple's Technical Note #18 that goes into
> detail about interrupt routines that play nice with AppleTalk, etc.  I
> think the grail of 57,600 BPS lies down one of those paths.  I'll need
> another vacation's worth of geek-time to get that sorted out.

The key is to get to the metal and bypass all the serial port
firmware.  If a 1MHz 6502 can drive an SSC at 115kbps, then a
2.8MHz 65816 shouldn't have any trouble driving an SCC at 57kbps.

Polling is the key.

-michael

New, faster SUDOKU v2.0 solver for Apple II's!
Home page:  http://members.aol.com/MJMahon/

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