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Aucbvax.5902 fa.works utcsrgv!utzoo!decvax!ucbvax!works Thu Jan 21 22:44:10 1982 WorkS Digest V2 #11 >From JSOL@USC-ECLB Thu Jan 21 22:41:56 1982 Works Digest Friday, 22 Jan 1982 Volume 2 : Issue 11

Today's Topics: Hard Copy Output - Not Needed? Query Reply - Everything In Main Memory Multics - Quicksorts ----------------------------------------------------------------------

Date: 21 Jan 1982 0942-EST From: WALKER at CMU-20C Subject: hard copy

There is certainly no use for an optical character reader to insert a machine-generated document into another machine, but what about all the books, papers, etc already laying around? Most of this stuff can be safely thrown away (look around your office, or at least mine), but a lot of it is relatively timeless. It would be a royal pain to have someone type in the Library of Congress by hand.

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Date: 21 Jan 1982 1457-PST From: BILLW at SRI-KL Subject: Re: Large address spaces

Re: the whole world is not in main memory (for example my terminal).

Well, It could be, maybe it should be, and on a lot of workstations, it IS. DMA displays have all sorts of advatages over any other type of display. Its just that if the display bitmap takes 128K bytes, and your processor only addresses 64K, you are in a lot of trouble.

WW

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Date: 21 Jan 1982 09:03:26-PST From: decvax!duke!unc!smb at Berkeley Full-Name: Steven M. Bellovin To: REM@MIT-MC Subject: Re: Multics

From REM@MIT-MC Thu Jan 21 08:55:16 1982 Via: duke!chico!ucbvax Date: 21 January 1982 01:34-EST From: Robert Elton Maas <REM MIT-MC AT> Subject: Re: Multics

To: chico!duke!unc!smb at UCB-C70

Quicksort is N^2 worst case, so even in main memory it isn't good. Thus it's a red herring. Anybody who would use it even when it all fits in realmemory (no thrashing) is a loser already and thrashing is beside the point. Some other methods of sorting are n log n worst case, and some of them can be made to run in virtual memory with much localness of accessing so as to avoid thrashing if real memory is small, even tiny.

Quicksort is n*log n in the average case, and generally does quite well, but that isn't my point at all. You've made it for me -- that some sorts "can be made to run in virtual memory with much localness of accessing", i.e., that the program *must* be aware that it may run in that environment, that awareness of the underlying structure *is* a concern of the programmer.

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