From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED, HTML_MESSAGE,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 28177 invoked from network); 30 Nov 2021 16:49:51 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 30 Nov 2021 16:49:51 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 59FE794613; Wed, 1 Dec 2021 02:49:49 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 7190693D60; Wed, 1 Dec 2021 02:48:18 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=ccc.com header.i=@ccc.com header.b="blCgaN1e"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id 1108693D60; Wed, 1 Dec 2021 02:48:16 +1000 (AEST) Received: from mail-qt1-f170.google.com (mail-qt1-f170.google.com [209.85.160.170]) by minnie.tuhs.org (Postfix) with ESMTPS id 7713293D29 for ; Wed, 1 Dec 2021 02:48:15 +1000 (AEST) Received: by mail-qt1-f170.google.com with SMTP id j17so20842884qtx.2 for ; Tue, 30 Nov 2021 08:48:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ccc.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=UDyFFIBR/OB+kiX1BzGbNfWyfyJfg+loAwm8tw80JN8=; b=blCgaN1elsT3n0tlWbG+NzVvVEut+eyGY9SqTRUPEt2mCDuNlPpieUrQu6t/2cFZq8 bZWWgltrylDZOUacAN/1it/KfdCbO4m7RjxbslMtvQYhpsC9fQSLQib810QCTYntaxfj xdSBps+a14Q0EifcwD2/tQff8JaVgzaUvrgfQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=UDyFFIBR/OB+kiX1BzGbNfWyfyJfg+loAwm8tw80JN8=; b=1v3gPGq7O46f3xXIK6s+oIpsBFY2HEEFPlma2USaqLlC8Rsm/Gbxa3RbfxRa6JyPdo 5a1aGu+pxvR/fxHAr85JVT/0t3VyTe0PYzEST6Zn1Xl15taWXmce4AMmrsUPoAlNOO7K RlIpI/Er0QblhEAYZsILG+sWC9A41UXgW/WR/4k/yVj2gmOBFxgnLMsm1nOu9UZNiO7g P5d3gjy5+JuQ+jYcaGskbroYEOnfERvntUZHFOmeySwBx2EEt0CPCQqqTJ+EmMmh8Det uYQjF/cmKo9cPFA2NNhYusYgnjLJztqPnOzmbbHRpnQ8JcC/eiOj1WMO/jqqtmRE+7Sz U/oA== X-Gm-Message-State: AOAM533s9zUga2PQISnyWFboE8y0nN8dgLFjbJMtasWLKYmrO38iOmZ/ 4V4+qNeOKeIYf23FtRWqsHNVbaevRQQbxAbRZXqRKCmHw4PfZQ== X-Google-Smtp-Source: ABdhPJw/7CSYVlNX0zLE4hWIW5qIfKL+0vayUmBcjR/NpQXOMiEHKukg8hKacj0ehQQ/GyDTDa8BOtZqPAtep0HMbLQ= X-Received: by 2002:a05:622a:14d3:: with SMTP id u19mr467609qtx.547.1638290894045; Tue, 30 Nov 2021 08:48:14 -0800 (PST) MIME-Version: 1.0 References: <010901d7e5c1$4a0c7c20$de257460$@gmail.com> In-Reply-To: <010901d7e5c1$4a0c7c20$de257460$@gmail.com> From: Clem Cole Date: Tue, 30 Nov 2021 11:47:48 -0500 Message-ID: To: COFF Subject: Re: [COFF] Encoding an ISA: Random Logic vs. Control Stores X-BeenThere: coff@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: Computer Old Farts Forum List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============2372384631597937054==" Errors-To: coff-bounces@minnie.tuhs.org Sender: "COFF" --===============2372384631597937054== Content-Type: multipart/alternative; boundary="000000000000c7577505d2045264" --000000000000c7577505d2045264 Content-Type: text/plain; charset="UTF-8" Moving to COFF as this is less UNIX and more computer architecture and design style... On Tue, Nov 30, 2021 at 3:07 AM wrote: > Given a random logic design it's efficient to organize the ISA encoding > to maximize its regularity. Probably also of some benefit to compilers in a memory-constrained > environment? > To be honest, I think that the regularity of the instruction set is less for the logic and more for the compiler. Around the time the 11 was being created Bill Wulf and I think Gordan as co-author, wrote a paper about how instruction set design, the regularity, lack of special cases, made it easier to write a code optimizer. Remember a couple of former Bell and Wulf students were heavily involved in the 11 (Strecker being the main one I can think of off the top of my head). Also remember that Gordan and the CMU types of those days were beginning to create what we now call Hardware Description Languages (HDL). Gordon describes in "Bell and Newell" (the definitive Computer Structures book of the 1970s) his Processor-Memory-Switch (PMS) diagrams. The original 11 (which would become the 11/20) was first described as a set of PMS diagrams. PMS of course, beget the Instruction Set Processor Language (ISPL) that Mario created a couple of years later. While ISPL was after the 11 had been designed, ISPL could synthesize a system using PDP-16 RTM modules. A later version from our old friend from UNIX land, Ted Kowalski [his PhD thesis actually], that could spit out TTL from the later ISPS simulator and compiler [the S being simulation]. ISPS would beget VHDL, which beget today Verilog/System Verilog. IIRC it was a lecture Gordon Gordan gave us WRT to microcode *vs.* direct logic. He offered that microcode had the advantage that you could more easily update things in the field, but he also felt that if we could catch the errors before you released the HW to the world, and if we could then directly synthesize, that would be even better - no errors/no need to update. That said, by the 11/40, DEC started to microcode the 11's, although as you point out the 11/34 and later 11/44, where more direct logic than the 11/40 - and of course Wulf would created the 11/40e - which writeable control store so they add some instructions and eventually build C.mmp. --000000000000c7577505d2045264 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Moving to COFF= as this is less UNIX and more computer architecture and design style...

On Tue, Nov 30, 2021 at 3:07 AM <pbirkel@gmail.com> wrote:
=
Given a random logic design = it's efficient to organize the ISA encoding to maximize it= s regularity.
Probably also of some benefit to compilers in a memory-constra= ined environment?
To be h= onest, I think that the regularity of the instruction set is less for the l= ogic and more for the compiler.=C2=A0 Around the time the 11 was being crea= ted Bill Wulf and I think Gordan as co-author, wrote a paper about how inst= ruction set design, the regularity, lack of special cases, made it easier t= o write a code optimizer.=C2=A0 Remember a couple of former Bell and Wulf s= tudents were heavily involved in the 11 (Strecker being the main one I can = think of off the top of my head).
Also remember that Gordan and the= CMU types of those days were beginning to create what we now call Hardware= Description Languages (HDL).=C2=A0 Gordon describes in "Bell and Newe= ll" (the definitive Computer Structures book of the 1970s) his Process= or-Memory-Switch (PMS) diagrams. =C2=A0 The original 11 (which would become= the 11/20) was first described as a set of PMS diagrams. =C2=A0 PMS of cou= rse, beget the Instruction Set Processor Language (ISPL) that Mario created= a=C2=A0couple of years later. =C2=A0 While ISPL was after the 11 had been = designed, ISPL could synthesize a system using PDP-16 RTM modules.=C2=A0 A = later version from our old friend from UNIX land, Ted Kowalski [his PhD the= sis actually], that could spit out TTL from the later=C2=A0ISPS simulator a= nd compiler [the S being simulation]. =C2=A0 ISPS would beget VHDL, which b= eget today Verilog/System Verilog.
<= br>
IIRC it was a lecture=C2=A0Gordo= n Gordan gave us WRT to microcode vs. direct logic.=C2=A0 He offered= that microcode had the advantage that you could more easily update things = in the field, but he also felt that if we could catch the errors before you= released the=C2=A0HW to the world, and if we could then directly synthesiz= e, that would be even better - no errors/no need to update. =C2=A0 That sai= d, by the 11/40, DEC started to microcode the 11's, although as you poi= nt out the 11/34 and later 11/44,=C2=A0where more direct logic than the 11/= 40 - and of course Wulf would created the 11/40e - which writeable control = store so they add some instructions and eventually build C.mmp.
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