From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from minnie.tuhs.org (minnie.tuhs.org [45.79.103.53]) by inbox.vuxu.org (OpenSMTPD) with ESMTP id 5660e2b6 for ; Sat, 31 Aug 2019 03:19:43 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id B64909C0BF; Sat, 31 Aug 2019 13:19:42 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id E1D8D9C0A7; Sat, 31 Aug 2019 13:19:29 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id B8F039C0A7; Sat, 31 Aug 2019 13:19:27 +1000 (AEST) Received: from mail.bitblocks.com (ns1.bitblocks.com [173.228.5.8]) by minnie.tuhs.org (Postfix) with ESMTP id C78D29C00B for ; Sat, 31 Aug 2019 13:19:26 +1000 (AEST) Received: from mob.bitblocks.com (mob.bitblocks.com [192.168.125.11]) by mail.bitblocks.com (Postfix) with ESMTP id 236861570CE9; Fri, 30 Aug 2019 20:19:05 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\)) From: Bakul Shah In-Reply-To: <88242A0D-D08E-47EB-84DC-A7205780A417@ccc.com> Date: Fri, 30 Aug 2019 20:19:04 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: <8BFD5926-B916-4AA2-A896-4BA9E5AFDB69@bitblocks.com> References: <1567196510.21824.for-standards-violators@oclsc.org> <20190830215202.GA974@mcvoy.com> <20190831011359.E9F491570CE9@mail.bitblocks.com> <88242A0D-D08E-47EB-84DC-A7205780A417@ccc.com> To: Clem cole X-Mailer: Apple Mail (2.3445.104.11) Subject: Re: [TUHS] dmr streams & networking [was: Re: If not Linux, then what?] X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: The Eunuchs Hysterical Society Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" It would be interesting to see its MMU details. > On Aug 30, 2019, at 7:46 PM, Clem cole wrote: >=20 > There was most definitely a TLB or as Dave called it =E2=80=98The = TB=E2=80=99 *** > 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=20 >=20 >=20 > *** west coast VS east coast training - calling it a TB vs a TLB. =20 >=20 > Sent from my PDP-7 Running UNIX V0 expect things to be almost but not = quite.=20 >=20 >> On Aug 30, 2019, at 9:13 PM, Bakul Shah wrote: >>=20 >>> On Fri, 30 Aug 2019 20:58:13 -0400 Clem Cole wrote: >>>=20 >>> 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 >>=20 >> 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? >>=20 >> 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.