An excellent point on voltage levels, Leav. I hadn't really looked in to that in much detail before, because the serial applications I've used have been between PIC microcontrollers and PC's, and I have been able to successfully ignore the voltage specs. Not particularly good practice, perhaps, but it has worked pretty reliably for me.
The
PIC Basic Pro Manual in the section on the "Serout" (serial out) command suggests:
Quote:
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While single-chip RS-232 level converters are common and inexpensive, thanks to current RS-232 implementation and the excellent I/O specifications of the PICmicro, most applications don't require level converters. Rather, inverted TTL (N300..N9600) can be used. A current limiting resistor is suggested (RS-232 is suppose to be short-tolerant).
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Not guarantees that that would work with on old Apple, though. I just know that for a few simple applications using PICs and Pic Basic Pro, I've been able to ignore the differences between TTL and RS-232.
Jason