Implementation of the Assembler

Abstract

This detailed presentation of the design and implementation of an assembler is given for several reasons. First the production of an octal oncoding for the assembler is a necessary part of the bootstrap theme running through this book. No program of this complexity would be written directly in octal, and the systematic approach described here is one way in which it might be derived. In fact the approach adopted might be used to produce any significant program in machine code. Of course, with more aids in the form of fully operational computers. much of the detail work might be avoided, but such an approach would pre-empt the full understanding of the operation of the computer and its low level software which we are seeking here. Finally, an assembler might be regarded as a very simple compiler, and as such its main components could be a suitable base from which consideration of the more formal and complex algorithms of a compiler might begin.