15 Aug
2005
15 Aug
'05
6:44 p.m.
In message <001e01c5a1fe$ad9c6480$0300a8c0 at downstairs2>, "Michael
Holley" write
s:
An early example of a bit banger serial interface was
the Motorola 6800
MIKBUG Monitor ROM. It used a parallel interface chip (MC6820 PIA) as a
bidirectional serial interface. It would work at 110 and 300 baud (some
people clocked it at 1200 baud.)
That reminds me or another little machine from Motorola. They
called it the Educator II (and was the first computer I ever
owned). Their cassette interface worked pretty much the same
way. They toggled a pin on the PIA in software for a simple
FM encoding at 110 baud. Even the receive side was software.
Brian L. Stuart