A Message Exchange for Computer Programs and Terminals.
ResearchPublished 1972
ResearchPublished 1972
Documentation of the Video Graphics System Message Handler (VMH), that provides interprocess communication and message switching among Video Graphics terminal users and multiaccess and personal programs running in the connected computers--which, at RAND, includes the entire ARPA Computing Network. VMH enables terminals and programs to communicate selectively, either one-to-one or multiplexed, across the boundaries set by computer system architecture. Message privacy is preserved. Written in OS/360 Assembler Language, VMH is a set of interrelated high-priority routines available to programs via macro instructions and to terminals via communication control commands. The message path scheme is separate from the message handling, which (1) permits users to be kept up to date about message path activity, and (2) makes the control system modifiable by simply adding new control requests and status values. VMH has operated almost continuously since early 1971, supporting 32 terminals. Tested throughput averages 600-850 messages/sec on a 360/65.
This publication is part of the RAND report series. The report series, a product of RAND from 1948 to 1993, represented the principal publication documenting and transmitting RAND's major research findings and final research.
This document and trademark(s) contained herein are protected by law. This representation of RAND intellectual property is provided for noncommercial use only. Unauthorized posting of this publication online is prohibited; linking directly to this product page is encouraged. Permission is required from RAND to reproduce, or reuse in another form, any of its research documents for commercial purposes. For information on reprint and reuse permissions, please visit www.rand.org/pubs/permissions.
RAND is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.