Being pedantic
about it, it appears you were bit-banging serial I/O over
lines of the IBM printer interface, in which case I think it becomes a
serial port :-).
Being pedantic about it, I'd say that twiddling more than one line
at once changes it from serial to parallel.
So an interface which transfers data bit-serially over a pair of
differentially-driving lines is a parallel interface? (2 lines are
changing at once)
I think that if you're sending data one bit at a time, that's a serial
interface. No matter whaty else you might be doing at the same time or
whether the conversion between that serial data and the parallel data
used by most microprocessors is done in hardware or software. A
bit-banged serial interface _is_ a serial interface, even if you're using
other lines on the same (parallel) port to do other things
Some older manuals refer to things like the Centronics interface as
'chracter serial, bit parellel' meaning the chracters are sent one after
the other but the bits for each character are all sent at once. Some old
digital measuring instruemnts have 'sigit parallel' interfaces. For
example the 9 display digits will be sent all at once over 36 wires (4
bit BCD for each digit).
Th HP11203 BCD interface for the 9800s is a converter from digit-parallel
data to digit-serial (but still bit-parallel) data. It takes in all the
digits, selects them one at a time and passes them on to the CPU I/O
register (where they then become bit-serial).
-tony
