RFC 190 (rfc190) - Page 1 of 16
DEC PDP-10-IMLAC communications system
Alternative Format: Original Text Document
Network Working Group P. Deutsch
Request for Comments: 190 Xerox Research Center, Palo Alto, CA
NIC: 7135 13 July 1971
DEC PDP-10 -- IMLAC COMMUNICATION SYSTEM
This report describes an operational system for communicating textual
display information between a main-site computer and a remote-display
processor.
The main site machine is a DEC PDP-10 with the BBN paging hardware
(henceforth TENEX).
The remote machine is a IMLAC PDS-1 (henceforth IMLAC).
Section (1) briefly describes the IMLAC hardware configurations.
Section (II) describes the display facilities presented to the
user.
Section (III) describes the system calls (JSYS calls) implemented
in the TENEX monitor to provide these facilities.
Section (IV) describes the formats of the messages used for
communication between TENEX and the IMLAC.
Section (V) analyzes the division of responsibility between the
two machines.
(1) Hardware configurations.
The standard IMLAC is a 16-bit minicomputer with 4K of 2 microsecond
core, a cycle-stealing display, an input keyboard, and an
asynchronous serial communication interface.
The display is normally programmed to draw characters using very
short vectors.
The display comes in two major configurations, depending on the
presence or absence of hardware for drawing long vectors.
In the sequel, specifications depending on the configuration will
be flagged LVH or non-LVH respectively.
The I/O system normally does not provide for interrupts when
characters arrive from the serial interface.
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