A Review of Available Microprocessors

INTRODUCTION The purpose of this review is to update the table of available microprocessors included in the first of a series of papers entitled 'An introduction to microprocessors' which appeared in this journal 1 and to provide an indication of recent development trends in this field. The original table, which is now over two years old, does not reflect many of the conceptual developments that have occurred in the intervening period. The advances have primarily been due to the increase in circuit component density achieved in N-channel metal oxide semiconductor (NMOS) integrated circuits. The levels of NMOS integration have typically been doubling every year since the mid 1960's as shown in Fig. 1. This is likely to continue well into the 1980's. Over the past two years this has led to the general availability of 16,384bit random access memory (RAM) chips, "65,536 bit read only memory (ROM) chips, 32,768 bit UV erasable electrically reprogrammable ROM's (UV-PROM) and a variety of microprocessor/microcomputer devices. The long-awaited 65,536 bit (64k) dynamic RAM will also become readily available this year.