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Aucbvax.4728 fa.works utzoo!decvax!ucbvax!works Tue Oct 27 20:14:31 1981 WORKS Digest V1 #25 >From JSol@RUTGERS Tue Oct 27 19:30:41 1981 WorkS Digest Wednesday, 28 Oct 1981 Volume 1 : Issue 25

Today's Topics: MC68000 Paging Query Lisp Machines: Not Everybody Likes To Program In Lisp ----------------------------------------------------------------------

Date: Friday, 23 October 1981 00:04-EDT From: Goldberg (Robert N. Goldberg) Re: MC68000 paging

Someone who works for a company that produces specialized computer systems has been telling me that they decided to build their next system around the Z8000 rather than the MC68000 because they had serious doubts about being able to do paging on the MC68000. They claim that there is a design problem that prevents instruction resumption after a page fault. I understand that Apollo solves the problem by using 2 68000 chips.

Having briefly studied the instruction set and architecture of the two CPU's, I see the MC68000 as superior for the application of this company (they want a large virtual address space that can be accessed from a high level language, and speed is important), and it seems to me that getting stuck with the funny segment addressing of the Z8000 will cause problems.

1) Is there a real problem implementing virtual demand paging on the MC68000?

2) Can anyone tell me some of the problems one faces when generating code from a compiler (e.g. C) for a segmented memory machine such as the Z8000? I know that you have to do array subscripting carefully, but what are some of the more insidious subtle problems that come up?

Bob Goldberg

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Date: 27 Oct 1981 15:14:19-PST From: decvax!pur-ee!purdue!cak at Berkeley Re: Lisp Machines

I may be called a heretic for this, but here goes. The Lisp Machine sounds very nice...I was really excited when I first saw the announcement. But,.... WHAT IF YOU DON'T WANT TO PROGRAM IN LISP? I personally am not crazy about Lisp. It is good for some things, but for most of my hacking, I prefer C (I fight with emacs because I have to do my extensions in MLisp. I understand why, but I don't have to like it.)

chris

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