Re: //c w/serial baud rate issue

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

Donnie wrote:
> Tom Greene wrote:
>
> > Donnie wrote:
> >
> > > I do have the skills to do such a modification, myself.  It looks like a
> > > wire i soldered across a couple pads and/or the oscillator.  Do you know
> > > exactly what is done to perform the mod?
> > >
> > > Donnie
> >
> >
> > There are some cut traces and some bridged pads. Here's a couple more
> > pics of what I can see after poking around with my multimeter... I
> > can't say for sure if these are the only modifications that are
> > necessary.
> >
> > http://cerberus.cowgod.org/apple2/iicserialfix-front.jpg
> > http://cerberus.cowgod.org/apple2/iicserialfix-back.jpg
> >
> > In these pics, red marks are cuts, blue marks are bridged. The
> > oscillator is marked 1.8432 MHz. The chip on the un-fixed boards is a
> > 74LS161.
> >
> > Personally I don't know that it would be worth trying to modify the
> > board...
> >
> > Tom
>
> I'd imagine that would be all that is all that there is to it.  I'd look 
> at the pinout of an LS161 first, though, to see if what that does makes 
> any sense.

The mods primarily isolate three of the four pads used by the crystal
oscillator (since ground is common to both packages), so that the
crystal output can replace the 'LS161 output.

It's a shame they ever tried to "cheat" the UART frequency in the
first place.  ;-(

-michael

Music synthesis for 8-bit Apple II's!
Home page:  http://members.aol.com/MJMahon/

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