A computer interface to a line printer has seven data

Chapter 4, Problem 4.22

(choose chapter or problem)

A computer interface to a line printer has seven data lines that control the movement of the paper and the print head and determine which character to print. The data lines are labeled A, B, C, D, E, F, and G, and each represents a binary 0 or 1. When the data lines are interpreted as a 7-bit binary number with line A being the most significant bit, the data lines can represent the numbers 0 to \(127_{10}\). The number \(13_{10}\) is the command to return the print head to the beginning of a line, the number \(10_{10}\) means to advance the paper by one line, and the numbers \(32_{10}\) to \(127_{10}\) represent printing characters.

(a) Write an equation for the variable X which is 1 iff the data lines indicate a command to return the print head to the beginning of the line.

(b) Write an equation for the variable Y which is 1 iff there is an advance paper command on the data lines.

(c) Write an equation for the variable Z which is 1 iff the data lines indicate a printable character. (Hint: Consider the binary representations of the numbers 0–31 and 32–127 and write the equation for Z with only two terms.)