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AN EXECUTIVE SYSTEM FOR A DEC 339 COMPUTER DISPLAY TERMINAL

IP.com Disclosure Number: IPCOM000128426D
Original Publication Date: 1968-Dec-01
Included in the Prior Art Database: 2005-Sep-15

Publishing Venue

Software Patent Institute

Related People

Jackson, James H.: AUTHOR [+3]

Abstract

This report describes a real-time multiprogramming software system for a DEC 339 computer display terminal, which may communicate with an external computer through a serial-synchronous data set. The system is designed to support both programs which require the attention of an external computer while they are being executed and programs which are independent of external computation service. For either type of program, the entire graphics support is provided by the 339 system, but the interpretation of the relations implied by the graphics may be performed either in the 339 or in an external computer. Multiprogramming facility is provided to facilitate effective use of I/O devices in order to cope with the demands of a real-time environment.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

AN EXECUTIVE SYSTEM FOR A DEC 339 COMPUTER DISPLAY TERMINAL

James H. Jackson THE UNIVERSITY OF MICHIGAN Technical Report 15

CONCOMP: Research in Conversational Use of Computers
F. H. Westervelt, Project Director ORA Project 07449

Supported by:

ADVANCED RESEARCH PROJECTS AGENCY DEPARTMENT OF DEFENSE WASHINGTON, D. C.

CONTRACT NO. DA-49-083 OSA-3050 ARPA ORDER NO. 716

Administered through: OFFICE OF RESEARCH ADMINISTRATION ANN ARBOR

December 1968

ABSTRACT

This report describes a real-time multiprogramming software system for a DEC 339 computer display terminal, which may communicate with an external computer through a serial- synchronous data set. The system is designed to support both programs which require the attention of an external computer while they are being executed and programs which are independent of external computation service. For either type of program, the entire graphics support is provided by the 339 system, but the interpretation of the relations implied by the graphics may be performed either in the 339 or in an external computer. Multiprogramming facility is provided to facilitate effective use of I/O devices in order to cope with the demands of a real-time environment.

TABLE OF CONTENTS

ABSTRACT.....iii

1. INTRODUCTION.....1

2. SYSTEM ORGANIZATION.....3
2.1 Bootstrap Arrangement....3
2.2 Tasks.....4
2.3 States of the System.....4

University of Michigan Page 1 Dec 01, 1968

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AN EXECUTIVE SYSTEM FOR A DEC 339 COMPUTER DISPLAY TERMINAL

2.4 Entering System State.....5

3. SYSTEM SUBROUTINES.....7
3.1 Word Queues.....8
3.2 Task Scheduling and I/O Device Allocation.....11
3.3 Format Conversions.....16
3.4 Buffered I/O.....17
3.4.1 Dataphone I/O.....18
3.4.2 Paper Tape I/O.....22
3.4.3 Teletype I/O.....25
3.5 Nonbuffered I/O.....26
3.6 Push-Button Processing.....29
3.7 Display Control Communication.....31
3.8 Light Pen Tracking.....32
3.9 Display Structure Topology.....35
3.10 Level Modification.....40
3.11 Text List Manipulation.....61

4. IDLE-TIME TASK.....64
4.1 Copy Functions.....64
4.2 Scheduling of User Tasks.....67
4.3 Clearing the Task Queue or Display Storage.....67
4.4 Teletype to Dataphone Transmission.....68
4.5 Entering User State.....68

5. SYSTEM CAPABILITY.....69

BIBLIOGRAPHY.....70

APPENDICES A LISTING OF THE EXECUTIVE SYSTEM.....A-1
B SUMMARY OF SYSTEM SUBROUTINES.....B-1
C SUMMARY OF IOT INSTRUCTIONS.....C-1
D ASSEMBLY LANGUAGE.....D-1

1. INTRODUCTION

The objective of this report is to describe the conceptual organization of the SEL (Systems Engineering Laboratory's) Executive System for a 339 computer display terminal, as well as to provide a manual for its use. More specifically, the hardware configuration for which the System was designed consists of the following items (plus necessary interfaces, multiplexors, etc.): DEC PDP-9 with at least two 8192-word memory banks DEC KE09A extended arithmetic element DEC 338 display c...