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An Interface Between the PDP-11 Computer and the IMSAI Microcomputer

IP.com Disclosure Number: IPCOM000128694D
Original Publication Date: 1978-Dec-31
Included in the Prior Art Database: 2005-Sep-16
Document File: 14 page(s) / 42K

Publishing Venue

Software Patent Institute

Related People

J. Michael Moshell: AUTHOR [+4]

Abstract

The purpose of this study is to design an interface between the PDP-11/34 minicomputer and the IMSAI 8080 microcomputer. An interface service request is initiated when the IMSAI interrupts the PDP-11. Data is transferred 8 bits (a "byte") at a time asyn-chronously via the interface at up to approximately 40,000 bytes per second. Three demonstration programs are presented. The inter-face is expandable to allow up to sixteen microcomputers to interface to a PDP-11.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

An Interface Between the PDP-11 Computer and the IMSAI Microcomputer

J. Michael Moshell Andrew Warm (Wang Shenq-Yen)

CS-78-29 November 1978

CONTENTS

CHAPTER 1 Introduction ,., 2

CHAPTER 2 Design Procedures , ,., 3

CHAPTER 3 Principles of Operation 8 CHAPTER 4 Programming , , 18 CHAPTER 5 Summary , : 22

BIBLIOGRAPHY .................................................. 24

APPENDIX A Schematics and Wiring Charts 25 APPENDIX B Test Programs 39

APPENDIX C Example Block Transfer Programs , 53

ABSTRACT

The purpose of this study is to design an interface between the PDP-11/34 minicomputer and the IMSAI 8080 microcomputer. An interface service request is initiated when the IMSAI interrupts the PDP-11. Data is transferred 8 bits (a "byte") at a time asyn-chronously via the interface at up to approximately 40,000 bytes per second. Three demonstration programs are presented. The inter-face is expandable to allow up to sixteen microcomputers to interface to a PDP-11.

The purpose of this study is to design an interface between the PDP-11/34 minicomputer and the IMSAI 8080 microcomputer. An interface service request is initiated when the IMSAI interrupts the PDP-11. Data is transferred 8 bits (a "byte") at a time asyn-chronously via the interface at up to approximately 40,000 bytes per second. Three demonstration programs are presented. The inter-face is expandable to allow up to sixteen microcomputers to interface to a PDP-11.

CHAPTER I INTRODUCTION

The Computer Science Department of the University of Tennessee is in the process of creating a minicomputer. laboratory. The Lab currently consists of two microcomputers and one PDP- 11/34 minicomputer. The PDP-11/34 has 64K words of memory, 7.5 megabytes of main disk

University of Tennessee Page 1 Dec 31, 1978

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An Interface Between the PDP-11 Computer and the IMSAI Microcomputer

storage, an RX-01 floppy disk drive, and four time.-.shard terminals. The UNTX operating system is used. The two microcomputers are the IMSAI 8080 and the Xitan Alpha 2. The I'MSAT 8080 microcomputer is equipped with 28 kilobytes of memory, a floppy disk drive, a "TV Dazzler" color graphics system, and analog-digital I'/0 divices. The IMSAI operates under the CP/M operating system. The Xitan Alpha 2 microcomputer has 18 Kilobytes of memory, a resident ROM monitor, another TV Dazzler, and audio cassette storage. It is highly desirable that, in the future, each of the micro-computers will appear to the PDP-11/34 as a single timesharing terminal; and the PDP-11/34 will appear to each microcomputer as if it were a floppy disk drive. In more detail, each microcomputer will contain a small ROM-based monitor used to store and load files to the PDP-11/34. One command to that monitor will make the entire microcomputer a terminal on the PDP-11/34 so that the PDP-11/34 can, for instance, generate images and display them on the graphics display using the microco...