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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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