15 Nov
2015
15 Nov
'15
6:28 a.m.
All Centronics ports have 8 bits going one way, and 4
"handshake" bits
going the other way.
That's a very PC-centric statement for you, and I am not convinced it's even true
on IBM PCs and compatibles!
There are plenty of machines that have 7 or 8 data bits output, automatic strobe
when the CPU writes to that output port and just a single busy pin input.
On the PC, there are indeed 8 data output lines. But there are also 4 more
control output lines that are fully under program control (strobe, etc) and
4 (or is it 5) input lines normally used for printer status input.
-tony