Welcome to Computer Systems, by J. Stanley Warford, where you can learn about the textbook and download resources.

What’s New – Pep/9 Command Line Simulator

Version 9.3.0

This version fixes the following bugs.

  • No longer hangs when given a bad Pep9CPU program.
  • No longer produces cycle numbers on UnitPre and UnitPost lines when saving to a file.

This version provides the following improvements.

  • Revised flag usage and -h output.
  • Apple signed app for Mac OS X.

Version 9.2

This version is the result of a refactorization that consolidates the code from four different applications – Pep/9, Pep/9 CPU, Pep/9 Terminal, and Pep/9 Micro – into a single suite of software for ease of maintenance. This is the first release of the Pep/9 Terminal application.

The Pep9Term application is designed to facilitate the batch grading of homework assignments. The application uses the assembler from the GUI version and produces trace tag warnings as well as fatal error messages.

Usage for assembling a .pep source program is

pep9term asm -i source.pep -o assembled.pepo

Usage for running a .pepo machine language program is

pep9term run -s asm.pepo -i charIn.txt -o charOut.txt

There is also a -m max_Steps option to set the maximum number of steps executed before aborting. The limit guarantees program termination when students submit programs containing endless loops. The default value is 25000 steps.