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Aucbvax.5294 fa.works utzoo!decvax!ucbvax!works Tue Nov 24 00:38:17 1981 WorkS Digest V1 #39 >From JSol@RUTGERS Tue Nov 24 00:34:45 1981 WorkS Digest Tuesday, 24 Nov 1981 Volume 1 : Issue 39

Today's Topics: Programming Environments - Request For References MC6800 Paging ----------------------------------------------------------------------

Date: 18 November 1981 15:05 From: Eugene Bordelon <EPB AT BTL-IHUXO> Reply-to: ihnss!ihuxs!ihuxp!ihuxo!epb at Berkeley Subject: WorkS Digest V1 #38: Programming environments To: Stavros M. Macrakis at MIT-MC

I am interested in reading further about various approachs to programming environments. Could you list (in full) some references?

Eugene Bordelon

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Date: Sunday, 22 November 1981 18:01-EST From: FEINBERG at CMU-20C Subject: [G.KTK: 68000 Paging] cc: KTK at AI

This message was sent to me by a Hardware designer who is currently working on implementing his own 68000 system. He claims you can do totally winning paging on the 68000 without kludging two processors together, by adding hardware to detect page faults, and signalling a bus error which such an event takes place. If the following is true, why did people go to such great lengths to implment paging?

Date: Friday, 20 November 1981 22:54-EST From: Kristofer Karas <G.KTK AT MIT-EECS MIT-AI> To: FEINBERG Re: 68000 Paging

Howdy! Ah, but the 68000 has something even better in that it is really versatile; it has a BERR (bus error) interupt that can either re-run the bus cycle in case of parity error in memory, or call a routine in the monitor to modify the page and swap in/out virtual memory. This single input can (under complete control of the Monitor) trigger any special routine the user wishes when page faults or other such immediate conditions occur. Combine this with status outputs that can tell outside hardware (page-mappers for that matter) whether the currently running program is Monitor (privileged) or User (ordinary) and you have the basis for a really sophisticated virtual memory/multi user/multi tasking system with a minimum of external hardware! --Kris

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