Re: Apple IIc serial port problem?

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

In article <318ee9$clb@info2.rus.uni-stuttgart.de>,
Wulf Hofbauer <zcaa1122@rpool7.rus.uni-stuttgart.de> wrote:
> In article <CtLp7z.1Hs@actrix.gen.nz>,
> David Empson <dempson@actrix.gen.nz> wrote:
> >The fix involves a motherboard swap.  The revised IIc motherboard used
> >a 1.8432 MHz crystal to produce the correct speed for the serial ports.
> ...
> >This will give you a number which identifies the ROM version.  Version
> >255 is the original IIc ROM, which almost definitely means you have
> >the original motherboard.
> 
> I bought both of my //c's with the original ROM. Both have however a
> separate oscillator for port 2.

The crystal is associated with port 2, but its signal is also fed to
the ACIA for port 1.

OK, so Apple released the revised motherboard with a crystal for the
serial ports before they released the UniDisk version of the ROM.  I
think these systems will be rather rare though - yours is the first
case I've heard of the revised motherboard being supplied with the
original ROMs.  It may be related to country: if Apple had large
stocks of the original ROM for a particular country, they may have
shipped the new motherboard with the old ROM.

Another possibility is that all International (non-US) IIcs have the
revised motherboard (the IIc I have here is a US model donated to my
user group by Steve Wozniak in 1984).
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand