fast code and no morals

johnl at ima.UUCP johnl at ima.UUCP
Wed Jan 29 09:04:00 AEST 1986

The loop unwound into switch hack has been around for a long time.  We used 
it at Yale in 1977 for a terminal emulator running on an 11/05 which was a 
front end to an 11/45 running the 6th edition Unix, recently upgraded from 
5th edition.  The terminal emulator spent too much of its time doing 
scrolling (including region scrolling) so we unwound the loops, using the 
switch hack to deal with the edges of regions.  Worked great then, works 
great now.  That particular time, it was concocted by John Mostenan and Bob 
Tuttle.  It's evidently been rediscovered a zillion times since.  

John Levine, ima!johnl 

PS: Writing our 11/05 C code so that the 11/45 C compiler wouldn't emit any 
instructions that the 11/05 couldn't execute, like multiply and divide, was 
the hard part.  

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