Aucbvax.5536
fa.works
utzoo!decvax!ucbvax!works
Thu Dec 24 00:30:52 1981
WorkS Digest V1 #47
>From JSol@RUTGERS Thu Dec 24 00:21:16 1981
Works Digest Thursday, 24 Dec 1981 Volume 1 : Issue 47
Today's Topics:
Administrivia
Paging On Other Hardware
National Semiconductor NS16032s - Availability
Commentary - Contents Of This Digest
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Date: 20 Dec 1981 1924-EST
From: Jonathan Alan Solomon <JSOL AT RUTGERS>
Subject: Administrivia
An old bug involving truncated messages just cropped up while sending
Monday's digest. There was no digest yesterday. Let me know if you
did not receive a complete digest on Monday, and I will resend one to
you.
This is the final digest of the year. I want to wish everyone a very
Merry Christmas, and a Happy New Year. Next digest is scheduled for
the 4th of January.
Cheers,
JSol
------------------------------
Date: 21 December 1981 23:17 est
From: SSteinberg.SoftArts at MIT-Multics
Subject: stacks on the 68000
Sender: COMSAT.SoftArts at MIT-Multics
I thought that 68000 stack references went to memory. If so, the two
CPU paging kludge would work with no modifications. Is the stack
register a really weird kludge?
[FLAME ON]
The VAX paging system appears to offer no improvements in basic design
since the work done on the ATLAS in the early 60's. Granted the
hardware support is much better but I get the impression that the VAX
paging scheme is needlessly complex!
I also noticed that people cannot figure out the second step of the
reasoning chain which begins:
The reason for paging is to provide a large memory space
in a small physical memory.
The next step is:
The reason to have a large memory space is to provide a
large [object] name space.
Large name/address spaces eliminate the need for vasty crocks such as
overlay managers, data object paging managers and explicit user disk
I/O. A great deal was written about this in the early sixties but as
usual the industry is still 20-30 years behind the software
technology.
------------------------------
Date: 22 Dec 1981 02:27:29-PST
From: decvax!microsoft!gordon at Berkeley
There are currently 'several' National Semiconductor NS16032s which
are primarily functional. A completly functional chip is expected
soon, the MMU chip will be available around mid-year. It is
interesting to note that the 16032's MMU is a dual-level virtual
memory system, with an associative LRU memory to hold the mapping
elements.
The MMU also has lots of fancy debugging go-fast in it, such
as hardware breakpoints, and instruction back-tracing.
The architecture is very good, and it looks like the initial
10mhz part will run 'c' a little bit faster than the 8mhz 68000. The
hardware people claim that the internal layout of the chip will allow
a 2 to 1 improvement in speed, without requiring faster clocks and
memorys, when they do their next design itteration.
------------------------------
Date: 22 December 1981 22:06-EST
From: Brian P. Lloyd <LLOYD MIT-MC AT>
Subject: Content of this digest
C'mon gang. I thought that this digest was created to discuss
workstations and not chips. I accept the fact that the 68000 has
demand paging problems, but I also feel that the hardware hacking
sould be discussed in Info-Micro. I personally would rather talk
about making useful workstations for PEOPLE and what approaches other
manufacturers have taken. I guess I am interested in ideas rather
than engineering.
Brian
[I agree that the discussion of paging hardware for a specific
microcomputer should be best discussed on INFO-MICRO, but as the
discussion has started (with today's digest) to branch out to a more
general paging discussion, there is really no better forum to discuss
it (hint: The VAX is NOT a microcomputer). I don't advocate creating a
INFO-PAGING-HARDWARE digest, but messages about any other topic will
take precedence. Anyone wanting to discuss this, or any other policy
or mechanical issue of the WorkS digest, please send mail to
WORKS-REQUEST@MIT-AI, not to the whole list. -JSOL]
------------------------------
End of WorkS Digest
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