In this chapter we have explained the operation of the interface board power supply, port interface, and LED Driver circuits. These circuits allow the parallel port of the PC to interface with the interface board and test operation of programs.
We learned how to develop C++ programs for sending and receiving bytes of data through the three addresses associated with the parallel port of the PC. These programs printed their results to the screen using either the cout object (as we did in Chapter 1), or using the functions of the printf() family. We also explained a small subset of the format specifiers that the printf() function uses.
The Exclusive OR bitwise operator was used to toggle some of the data bits we transmitted through the parallel port. Bitwise operators are a very useful part of the C and C++ languages and allow us to manipulate specific bits within a byte.