A Simple Teaching Computer

Abstract

This chapter Introduces for the first time a simple computer and in so doing draws together material from earlier chapters. The relevance of binary representation of data and instructions is explained as is the importance of the three basic computer elements: the control unit the arithmetic unit and the store. The concept is introduced of a binary word of standard length — an instruction word — which may be used to represent both orders and the locations, the addresses, at which data is stored. In this simple machine which has an eight-bit word-length, eight simple orders are possible and only thirty-two locations containing data may be addressed. Nevertheless, in spite of the limited instruction set and the small number of address locations, the chapter and its various figures illustrate in detail how data is routed within the machine, how orders are executed and how store locations are addressed. For simplicity, the machine operates in serial fashion in contrast to most modern machines which operate in parallel mode.

The chapter concludes with consideration of the serious limitations of the simple machine which has just been discussed. The Problems at the end of the chapter encourage students to consolidate their knowledge by drawing out a complete diagram of the machine using the detailed information contained in this chapter supplemented by limited design work.