During the course of our work, we have created several "Technical Notes". We are happy to share some of them with anybody who is interested.
The PC Parallel Port is a ubiquitous and useful interface for TTL level I/O. Its ease of use almost overcomes the limited
number of I/O lines. There are 12 output and 5 input lines. We created this Technical Note to help us when we use the
parallel port to interface to external devices.
The intention of these "crib sheets" is to provide a one page reference that can be used when designing or programming.
The ribbon cable that leads from the motherboard of a PC to the DB-9 or DB-25 comes in two flavors.
We discovered this by accident a number of years ago.
One can imagine the fustration when the port refused to work correctly.
To ease the confusion, we created our very first technical notice and posted it over the computer bench.
This notice is also useful in easing some of the confusion created by IBM's gross abuse of the RS-232 standard
when they laid out the PC serial port.
This page was last updated 10 May 2002.