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, RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 10772 invoked from network); 4 Feb 2021 07:31:16 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 4 Feb 2021 07:31:16 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 46E999C9E4; Thu, 4 Feb 2021 17:31:10 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 30D659C893; Thu, 4 Feb 2021 17:30:45 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id 6BBEF9C893; Thu, 4 Feb 2021 17:30:41 +1000 (AEST) X-Greylist: delayed 428 seconds by postgrey-1.36 at minnie.tuhs.org; Thu, 04 Feb 2021 17:30:38 AEST Received: from lb1-smtp-cloud8.xs4all.net (lb1-smtp-cloud8.xs4all.net [194.109.24.21]) by minnie.tuhs.org (Postfix) with ESMTPS id 643F19C0A7 for ; Thu, 4 Feb 2021 17:30:38 +1000 (AEST) Received: from cust-27e06a8f ([IPv6:fc0c:c122:908c:cb8e:3cc1:64e8:cd54:9bbd]) by smtp-cloud8.xs4all.net with ESMTPA id 7Yz8lGVWiW4yN7YzAlbcFt; Thu, 04 Feb 2021 08:23:28 +0100 Received: from arno by mail.ancienthardware.org with local (Exim 4.94) (envelope-from ) id 1l7Yz8-0007Yt-E9 for tuhs@minnie.tuhs.org; Thu, 04 Feb 2021 08:23:26 +0100 Date: Thu, 4 Feb 2021 08:23:26 +0100 From: Arno Griffioen To: tuhs@minnie.tuhs.org Message-ID: <20210204072326.GZ4829@ancienthardware.org> References: <202102030759.1137x7C2013543@freefriends.org> <202102030858.1138wuqd011051@freefriends.org> <27567.1612399305@hop.toad.com> <20210204013356.GA16541@mcvoy.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210204013356.GA16541@mcvoy.com> X-CMAE-Envelope: MS4xfPStV4j+2grFFH2QUypE5ceI3mtC5GE41Havssa459RBXtA6FmiQlBx38TLbuunuVyyDNjy1Pg1MB7dbX7970iV4uHD0StBiSzqT6xcNj4yd/FI1hwSS q5z4baZxoZ3cr4R5v9XcnE44IXmPY1xaN/M6TfQP0JfICVOvGC+eONm0L3qe6b0LDTr3Z3fc7LCDzZuNoe6Fe33voHrddazrJ+FBqvdop0EDqSA5FT1cNXE1 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 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 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.. 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.