Design and implementation of a microprogrammed computer

Includes bibliographical references (pages 73-75)This thesis is concerned with the application of microprogramming to the design and development of a data communications-oriented digital computer. The design philosophy is discussed, followed by a discussion of the computer architecture. Additional topics covered are a review of computer and micro programming history, and a typical system application for the computer that was designed and implemented for this thesis project. The modern digital computer has gone through many stages of development, evolving from a laboratory curiosity to an indispensable working tool in a relatively short period of time. The major stages of development can be defined by the active logic elements: vacuum tubes, discrete transistors, and integrated circuits. Along with these advances in hardware, significant changes have occurred in programming. The corresponding advances in software may be denoted as: machine languages and assemblers, high- level languages (example, FORTRAN) and monitors, and operating systems and multiprogramming. A recent trend in computer developments has been to make the computer control section programmable. Although the basic techniques of microprogramming have been known since the early 1950???s, they did not find widespread usage until the late 1960???s. The computer designed for this thesis project was designated the ADS-900. It is micro programmable and uses a bus-oriented, multiple general register structure. A 256 x 48 bit, read only memory is used to control operations for executing an IBM System 360/370 - compatible instruction set. A two???s complement, 16 -bit, data word is used. A powerful flexible input/output structure is included that allows installation of up to eight direct memory access channels and multiple, direct program channel controlled device s. Each direct memory access channel has 16 sub channels, each capable of handling multiple devices. The ADS -900 computer was successfully implemented and was used to control a data communications system. Present system plans involve interfacing with the IBM System 360/370 and a variety of data multiplexers and modems