THE UNIVERSITY OF MICHIGAN Memorandum 4 PDP-8/103A DATAPHONE INTERFACE
Original Publication Date: 1966-Nov-01
Included in the Prior Art Database: 2005-Sep-15
Publishing Venue
Software Patent Institute
Related People
Lundstrom, Stephen F.: AUTHOR [+2]
Abstract
The Concomp Project's DEC 338 Display system is now interfaced to two Bell System 103A Dataphones. This memorandum describes the use of the system as well as the interface construction.
THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.
THE UNIVERSITY OF MICHIGAN Memorandum 4
PDP-8/103A DATAPHONE INTERFACE
Stephen F. Lundstrom
CONCOMP: Research in Conversational Use of Computers
ORA Project 07449
F. H. Westervelt, Director
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 November 1966
ABSTRACT
The Concomp Project's DEC 338 Display system is now interfaced to two Bell System 103A Dataphones. This memorandum describes the use of the system as well as the interface construction.
[ Chapter ] I. GENERAL DISCUSSION
The interface to the 103A Dataphones required only minimum hardware additions. It involved the use of the teletype control built into the PDP-8. Figure 1 shows the standard system configuration.
(Image Omitted: Figure containing following caption omitted: Figure 1. Standard PDP-8 TTY I/O Configuration.)
(Image Omitted: Figure containing following caption omitted: Figure 2, below shows the additions to the above basic system.)
(Image Omitted: Figure 2. Modified PDP-8 TTY I/O Configuration.)
Notice that the console typewriter is now essentially an independent console since it is connected to its own dataphone. In particular, it may be connected to the PDP-8 to operate as a
University of Michigan Page 1 Nov 01, 1966
THE UNIVERSITY OF MICHIGAN Memorandum 4 PDP-8/103A DATAPHONE INTERFACE
normal online teletype with one exception: the tape reader on the ASR 33 will advance as long as there is tape in the reader (similar to handling tape in the reader during interrupt control of the normal online configuration.
[ Chapter ] II. PROGRAMMING CONSIDERATIONS
The new system is programmed using the standard PDP-8 IOT Instructions for teletype I/O (see the PDP-8 User's Handbook). The programmer should note the comment above concerning the independence of tape advance from the TTY reader flag. Also, the programmer should note that many standard Bell System teletypes automatically generate a parity bit which appears as the high order bit of the 8-bit character code. In such cases, there will be no guarantee that the high order bit is set during input from the keyboard as is the case with the ASR 33 supplied with the PDP-8.
[ Chapter ] III. SYSTEMS CONSIDERATIONS
The new PDP-8 I/O configuration allows a wider degree of flexibility in the integration of the 338 Display into The Uni...