Documentation for the CHIP Computer System (Version 1.1)

Abstract

CHIP (Cornell Hypothetical Instructional Processor) is a computer system that was designed as an educational tool for teaching undergraduate courses in operating systems and machine architecture. This document constitutes the sole reference manual for the CHIP computer system. A simulator for this hypothetical system exists under the UNIX operating system. The CHIP architecture includes dynamic memory mapping suitable for implementing virtual memory, eight interrupt priority levels, memory-mapped input/output and two modes of processor operation. The central processor of CHIP is compatible with the PDP-11 at the user-mode instruction level. Therefore, any non-privileged code written for the PDP-11 can be executed on CHIP. Several new user and kernel-mode instructions have been added to CHIP for increased efficiency. The CHIP simulator also supports input/output devices such as terminals, drums, disks and printers. All interactions with CHIP take place through an operator's console being simulated on a terminal. Users can examine/alter memory locations, set breakpoints, detect the referencing of specified memory locations, start/stop execution, etc. through a console command language. Program global variables and functions can be referred to by symbolic name with the mapping to absolute addresses being performed automatically by the system. The software support environment for CHIP includes a C compiler, assembler and loader.