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 [thread overview]
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.
next prev parent reply other threads:[~2019-08-31 3:19 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
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]
-- strict thread matches above, loose matches on Subject: below --
2019-09-01 2:36 [TUHS] dmr streams & networking [was: Re: If not Linux, then what? Rudi Blom
2019-09-01 2:16 [TUHS] dmr streams & networking [was: Re: If not Linux, then what?] Rudi Blom
2019-08-31 9:43 Rudi Blom
2019-08-31 15:41 ` Clem Cole
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
2019-08-28 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 9:17 Paul Ruizendaal
2019-08-28 10:44 ` Angelo Papenhoff
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