We used the buffer 74LS245 for our project. It is an electronic chip that has 20 pins. Pin 20 is the +5V power pin, and pin 10 is the ground pin.This 74LS245 buffer chip has 8 inputs pins and 8 output pins. Pin number 1 is considered the direction pin; therefore, it’s labelled DIR. It is called the direction pin because it controls the direction of the flow of electrical current. When DIR is held high, or 1, the input would be taken from the “A” side and the output would be given from the “B” side. In the same manner, when DIR is held low, or 0, the input is taken from the “B” side and the output would be given from the “A” side. When pin #19 is +5V, no information moves from A to B or B to A. When pin 19 is 0V, information flows from A to B or B to A depending on the wiring of pin 1. Pins 2-9 (A1-A8) and pins 18-11 (B1- B8) are the data pins.

We used The Turing programming language to reads the input status of the parallel port, and to write to the parallel port as integers. However, to determine the status of a specific pin of the input of the parallel port we needed to isolate that specific pin. The table on the left shows the way we isolate input pins for the purpose of decision making. We take the input from the pin like below:
S3 := ((input div  8) mod 2)
S4 := ((input div 16) mod 2)
S5 := ((input div 32) mod 2)
S6 := ((input div 64) mod 2)