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From: Bakul Shah <bakul@bitblocks.com>
To: Clem cole <clemc@ccc.com>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] dmr streams & networking [was: Re: If not Linux, then what?]
Date: Fri, 30 Aug 2019 20:19:04 -0700
Message-ID: <8BFD5926-B916-4AA2-A896-4BA9E5AFDB69@bitblocks.com> (raw)
In-Reply-To: <88242A0D-D08E-47EB-84DC-A7205780A417@ccc.com>

It would be interesting to see its MMU details.

> On Aug 30, 2019, at 7:46 PM, Clem cole <clemc@ccc.com> wrote:
> 
> There was most definitely a TLB or as Dave called it ‘The TB’ ***
> Remember Dave Cane (Masscomp hw lead) was part of the 780, led the 750 and designed the BI before he left dec.  He was a bus and memory specialist 
> 
> 
> *** west coast VS east coast training - calling it a TB vs a TLB.  
> 
> Sent from my PDP-7 Running UNIX V0 expect things to be almost but not quite. 
> 
>> On Aug 30, 2019, at 9:13 PM, Bakul Shah <bakul@bitblocks.com> wrote:
>> 
>>> On Fri, 30 Aug 2019 20:58:13 -0400 Clem Cole <clemc@ccc.com> wrote:
>>> 
>>> Actually not in lock step.  They were independent.  One was called the
>>> executor and the other the fixer.  When a fault was detected the executor
>>> was sent wait stated while the fixer handled the fault and refilled the
>>> TLB.   Once the TLB was set to instruction was allowed to complete.    Btw
>>> when the 68010 was released the pals on the board were changed to allow the
>>> executor to actually take the fault and do something else while the fixer
>>> replaced the TLB entry
>> 
>> As I remember, the issue with 68000 was that instructions were
>> not restartable so in case of accessing memory that didn't
>> exist, you couldn't take a segfault and do anything useful.
>> This is why you needed a second processor to deal with an
>> external MMU. There would have been no TLB unless you actually
>> added an external TLB -- but an external CAM would've been
>> very expensive. May be a direct map?
>> 
>> What we did at Fortune was to utilize a 4 entry external map:
>> text, data, extra and stack.  When a new function was invoked
>> it would do a 'probe'. If the probe caused a segfault, stack
>> was extended in the handler. The probe didn't have to be
>> restartable. So we didn't need a second 68k. This logic may
>> have been in the V7 port we started from.


  parent reply index

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-28  9:17 Paul Ruizendaal
2019-08-28 10:44 ` Angelo Papenhoff
2019-08-28 17:57 Doug McIlroy
2019-08-28 18:05 ` Adam Thornton
2019-08-28 18:08 ` arnold
2019-08-28 18:27 ` Warner Losh
2019-08-28 18:34   ` Warner Losh
2019-08-28 21:54 ` Rob Pike
2019-08-29  6:43   ` arnold
2019-08-29  7:39     ` Rob Pike
2019-08-29 16:26       ` arnold
2019-08-29  3:29 ` Lawrence Stewart
2019-08-29  4:10   ` Larry McVoy
2019-08-28 18:41 Doug McIlroy
2019-08-28 18:49 ` arnold
2019-08-28 19:03   ` Chet Ramey
2019-08-28 19:05     ` Larry McVoy
2019-08-29 14:58       ` Jason Stevens
2019-08-29 16:25         ` arnold
2019-08-29 16:38           ` Ralph Corderoy
2019-08-29 17:35             ` arnold
2019-08-28 21:55 ` Rob Pike
2019-08-28 22:29   ` George Michaelson
2019-08-28 22:36     ` William Pechter
2019-08-28 23:02       ` Arthur Krewat
2019-08-29  0:11       ` Clem cole
2019-08-29  0:18         ` George Michaelson
2019-08-29  6:27         ` Lars Brinkhoff
2019-08-30 20:21 Norman Wilson
2019-08-30 20:28 ` Larry McVoy
2019-08-30 20:39 ` Clem Cole
2019-08-30 21:52   ` Larry McVoy
2019-08-31  0:58     ` Clem Cole
2019-08-31  1:13       ` Bakul Shah
2019-08-31  2:46         ` Clem cole
2019-08-31  2:57           ` Clem cole
2019-08-31  3:14             ` Gregg Levine
2019-08-31  3:47               ` Clem cole
2019-08-31  3:38             ` Bakul Shah
2019-08-31  5:37             ` Dave Horsfall
2019-08-31 19:03               ` Clem Cole
2019-09-05  5:11                 ` Al Kossow
2019-09-02  8:28               ` Peter Jeremy
2019-09-02 23:26                 ` Dave Horsfall
2019-08-31  3:19           ` Bakul Shah [this message]
2019-08-31  9:43 Rudi Blom
2019-08-31 15:41 ` Clem Cole
2019-09-01  2:16 Rudi Blom
2019-09-01  2:36 [TUHS] dmr streams & networking [was: Re: If not Linux, then what? Rudi Blom

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