RFC 190 (rfc190) - Page 1 of 16

DEC PDP-10-IMLAC communications system

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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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