Aucbvax.2240
fa.works
utzoo!duke!decvax!ucbvax!works
Sun Jul 12 04:11:56 1981
Keystroke log / replay method of recovery
>From WorkS-REQUEST@MIT-AI Sun Jul 12 04:05:55 1981
The "replay" method of protecting a user from a crash during
an editing session was first used, to my knowledge, by Butler
Lampson and Charles Simonyi of PARC, in both the Bravo and
BravoX editing systems. A relatively recent Seybold report
covers BravoX in some detail.
-- Martin <HAEBERLI AT PARC-MAXC>
Convergent did not invent the keystroke log / replay method:
it was invented (as far as I know) by Charles Simonyi and
Butler Lampson for the PARC Bravo editor sometime around
1974. Replaying keystrokes is a special case of the comment
I made a couple of messages ago about logging state changes.
It still requires that the log be kept in a place that is
immune to crashes. What Bravo does is update the disk copy
of the log after every command, and every 20 characters or
so during text typein. It is a nice, cheap method for
protecting against a class of common failures.
-- Deutsch at PARC-MAXC
The rand editor does the same thing (with keystroke files).
-- decvax!duke!chico!esquire!nrh at Berkeley
Ok, ok. It's not new. Please don't send me any more mail.
My mailbox was swamped with informative replies. I should
have known better since the system hackers at CT were Xeroids
in previous incarnations. I should have guessed that replay
was in Bravo but didn't check before commenting (load brain
before shooting mouth). Sorry.
-- Brian <LLOYD AT MIT-AI>
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