Multics 832 entries
29 Aug 2017

Glossary - J

Glossary of Multics acronyms and terms. Entries by Tom Van Vleck ([THVV]) unless noted.


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Janus
[Wren McMains] Relational data base management system developed as part of the Consistent Systemby Jeff Stamen and Bob Wallace. Later development was the responsibility of Wren McMains. This data analysis application became one of the primary planning tools used on the United States Air Force Data Services Center system. Janus probably accounted for more CPU usage on those systems than all other programs put together during the 1970's.

jladdae
[BSG] (for "just logout and don't do anything else", pronounced, variously, jellad-eye, jellad-ey, or gelatti) A SIPB command (probably written by Charles Davis) that called the supervisor primitive to destroy the current process deliberately bypassing the user-ring process cleanup code invoked by the normal logout command, including the PL/I finish condition handlers and run unit cleanup.

jladdae arose from the conflict between the flexibility and robustness of the user ring process environment, resulting in its inability to support dependable cleanup code, as well as belief that these cleanups were largely worthless. Undebugged user code would damage the data needed by these cleanup handlers, causing logout to fail, often enough to be a problem. This is a Multics design flaw.

The exotic, Middle-Eastern sounding name of jladdae (cf. jihad, "Aladdin"), a contemporary of the 1979 Iranian Revolution, prompted Dan Weinreb to remark, memorably, "Did you hear about the jladdae in Iran? The Shah was forced to log out, and not do anything else."