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=-1.0 required=5.0 tests=MAILING_LIST_MULTI, NICE_REPLY_A,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 5104 invoked from network); 4 Feb 2021 11:29:35 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 4 Feb 2021 11:29:35 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id B232A9C9B1; Thu, 4 Feb 2021 21:29:31 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 48DB69C7CB; Thu, 4 Feb 2021 21:28:55 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id A64769C7CB; Thu, 4 Feb 2021 21:28:51 +1000 (AEST) Received: from kvm5.telegraphics.com.au (kvm5.telegraphics.com.au [98.124.60.144]) by minnie.tuhs.org (Postfix) with ESMTP id 9D98F9C0A7 for ; Thu, 4 Feb 2021 21:28:50 +1000 (AEST) Received: from [10.210.249.17] (unknown [10.210.249.17]) by kvm5.telegraphics.com.au (Postfix) with ESMTP id DB0E6292D1 for ; Thu, 4 Feb 2021 06:28:49 -0500 (EST) To: tuhs@minnie.tuhs.org References: <202102030759.1137x7C2013543@freefriends.org> <202102030858.1138wuqd011051@freefriends.org> <27567.1612399305@hop.toad.com> <20210204013356.GA16541@mcvoy.com> <20210204072326.GZ4829@ancienthardware.org> From: Toby Thain Message-ID: Date: Thu, 4 Feb 2021 06:28:49 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210204072326.GZ4829@ancienthardware.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [TUHS] 68k prototypes & microcode 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: , Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On 2021-02-04 2:23 a.m., Arno Griffioen wrote: > On Wed, Feb 03, 2021 at 05:33:56PM -0800, Larry McVoy wrote: >> I have to admit that I haven't looked at ARM assembler, the M1 is making >> me rethink that. Anyone have an opinion on where ARM lies in the pleasant >> to unpleasant scale? > > 'Different' is what I would call it.. > > Years ago I did a bunch of assembly hacking on the original ARM2 used in the > Archimedes A3000, which was an amazingly fast CPU for the time. > > The thing that stood out on these CPU's to me, which was wildly different > to what I was used to (M68K, 6502, Z80/8080, VAX), was the fact that > many instructions were (somewhat) composeable. > > Aka. you can/could add varuous logical operations like AND, OR, etc. 'into' an > instruction like a load or store and it would take the same number of clock > cycles to execute it all in 1 go. That is immediately reminiscent of DG Nova, PDP-8 (and to a tiny extent, PowerPC). > > That was great for doing data manipulation at very high rates for the time > compared to the common CISC CPU's as you did not need to go through multiple > fetch and modify cycles. > > Reminiscent of some VLIW setups, but still more 'human readable' :) > > The original ARM1/2/3 design did have some oddities like status bits being > encoded in the top of the (23) address bits, which meant that later versions of > the original design had to do some memory tricks to use a bigger address > space and keep compatilibity to the original code. > > I suspect the current common ARM revisions since the move to the StrongARM > (ARM4) architecture, when DEC got involved and ARM became a standalone chip > design firm, have long fixed those oddities. > > Probably still retains the way in which it encodes it's instructions to make > a lot of common logic operations while shuffling data more efficient though.. ARM MCUs also have the "bit manipulation engine" for a similar goal, I think. --Toby > > Having said that.. (and bringing it more back to TUHS instead of COFF ;) ) > > The ARM2 and ARM3 based machines could already run UNIX with Acorn selling > RISC iX for a short time, which was a 4.3BSD port done in the late 80's > and early 90's. > > Very few of those were ever used/sold though as the Acorn Archimedes series > of machines were quite a bit more expensive than more widespread CISC machines. > Most were found in the UK and often in universities and the like. > > Bye, Arno. >