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PDP-8/338 EXECUTIVE SYSTEM

IP.com Disclosure Number: IPCOM000128417D
Original Publication Date: 1967-Jun-01
Included in the Prior Art Database: 2005-Sep-15
Document File: 21 page(s) / 72K

Publishing Venue

Software Patent Institute

Related People

Frantz, Daniel R.: AUTHOR [+3]

Abstract

This manual describes the first step taken to provide a coherent executive system for the Digital Equipment Corporation's Type 338 Programmed Buffered Display (a PDP-8 computer and a display controller that drives a cathode-ray tube). The hardware may be viewed as two different computers operating on the same storage area, but each with a different scheme for accessing data. In addition, the organization of the storage area (3 ";banks"; of 4096 words each, and 32 ";pages"; of 128 words each in each bank) makes it impossible to treat all data and programs in a uniform fashion. The system is an attempt to provide a flexible method of handling these two problems. The executive resides in core bank zero during the loading and execution of a program. Part of the executive is a relocatable linking loader that will load a binary tape produced by the MALICS assembler. A user's programs are put into core banks one and two, providing him with approximately 8,000 words of working core storage. During execution, a program may call on the Executive Subroutine Caller to aid in calling subroutines across the core bank boundaries. Also during execution a priority interrupt dispatcher (the ";monitor";) provides a flexible tool for input-output processing and an effective method for computer display interaction. After execution of a portion of his program the user may swap programs into and out of core while maintaining the integrity of his data files. These functions and additional features are explained in detail below. Thorough knowledge of the PDP-8 internal organization and some knowledge of the display controller is assumed. This information may be obtained from the PDP-8 User's Handbook (DEC-85) and the Programmed Buffered Display 338 Programming Manual (DEC-08-G61B-0). The ALICS-II Programmer's Manual (Information Control Systems, Inc., Ann Arbor) is required reading for the section on the MALICS assembler. This manual and the system it describes are subject to change at any time.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 7% of the total text.

Page 1 of 21

THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

PDP-8/338 EXECUTIVE SYSTEM

THE UNIVERSITY OF MICHIGAN Memorandum Daniel R. Frantz

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

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

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

administered through: OFFICE OF RESEARCH ADMINISTRATION, ANN ARBOR June 1967

TABLE OF CONTENTS

Credits.....v
Introduction.....1
1. Organization of Storage: "Program" and "Data".....2
2. The Librarian.....5
2.1 The Communicator.....5
2.1.1 Format of Commands.....6
2.1.2 Debugging Aids.....7
2.1.2.1 DUMP.....7
2.1.2.2 REPLACE.....7
2.1.2.3 GOTO.....8
2.2 Multicore Assembler-Loader System (MALS).....8
2.2.1 Initialization Commands.....8
2.1.1.1 START.....9
2.2.1.2 LINK.....9
2.2.2 Program Continuation Commands.....9
2.2.2.1 LOAD.....9
2.2.2.2 RESUME.....9
2.2.3 Execution.....11
2.2.4 The Loader.....13
2.3 Service Routine Connections.....15
2.3.1 System Service Routines.....15
2.3.2 Interrupt Service Routines (ISR).....16
2.4 Executive Subroutine Caller (ESC).....17
3 The MALICS Assembler.....18

University of Michigan Page 1 Jun 01, 1967

Page 2 of 21

PDP-8/338 EXECUTIVE SYSTEM

3.1 ALICS Changes.....18
3.2 Additional Pseudo-ops.....19
3.2.1 Data Field Reference Pseudo-ops.....20
3.2.1.1 FLDHER.....20
3.2.1.2 DJHER Expression.....20
3.2.1.3 FIELD Expression.....21
3.2.2 Program Name Reference Pseudo-ops.....21
3.2.2.1 ENTRY NAME.....21
3.2.2.2 SUBR NAME.....22
3.2.3 Data Name Pseudo-ops.....23
3.2.3.1 DATNAM NAME.....23
3.2.3.2 FBA NAME.....23
3.2.4 Routine Pseudo-ops.....24
3.2.4.1 PEND.....24
3.2.4.2 DEND.....24
3.2.4.3 END.....24
3.3 Overrides.....24
3.4 Absolute Programs.....25
4. The Monitor.....25
4.1 Interrupt Scheduling.....26
4.2 Interrupt Service Routine Format.....26
4.3 Monitor Calls.....27
4.3.1 Monitor Initialization.....27
4.3.2 Non-standard Interrupt Service Routines.....28
Appendix 1 Subroutine Calling Conventions.....29
Appendix 2 Start-up Procedures.....32
Appendix 3 Relocation Codes.....33

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CREDITS

In the fall of 1966, a series of meetings of the personnel associated with the Terminal Room Operations Group produced ideas leading to the general organization of the system described in this manual. Among the contributors were Allan, T. Antrim, D. Frantz, B. Herzog, J. Jackson,
S. Lundstrom, W. Seider, and R. Taylor. Subsequently, J. Jackson designed and programmed the interrupt monitor; R. Taylor modified and supplemented the ALICS assembler until it turned into MALICS; and the author programmed the loader/librarian and supervised the assembly of the various parts of the system.

INTRODUCTION

This manual describes the first step taken to provide a coherent executive system for the Digital Equipment Corporation's Type 338 Programmed Buffered Display (a PDP-8 computer and a display controller that drives a cathode-ray tube). The hardware may...