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, MAILING_LIST_MULTI,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 3123 invoked from network); 14 Mar 2022 19:16:18 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 14 Mar 2022 19:16:18 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 37A3E9D685; Tue, 15 Mar 2022 05:16:15 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id B0A669D605; Tue, 15 Mar 2022 05:15:02 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=papnet.eu header.i=@papnet.eu header.b="GyloiHOt"; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=messagingengine.com header.i=@messagingengine.com header.b="JW1uLrR3"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id 903169D605; Tue, 15 Mar 2022 05:11:09 +1000 (AEST) X-Greylist: delayed 471 seconds by postgrey-1.36 at minnie.tuhs.org; Tue, 15 Mar 2022 05:11:05 AEST Received: from wout4-smtp.messagingengine.com (wout4-smtp.messagingengine.com [64.147.123.20]) by minnie.tuhs.org (Postfix) with ESMTPS id 58F999D5FB for ; Tue, 15 Mar 2022 05:11:05 +1000 (AEST) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.west.internal (Postfix) with ESMTP id 2D7D33200583 for ; Mon, 14 Mar 2022 15:03:12 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute3.internal (MEProxy); Mon, 14 Mar 2022 15:03:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=papnet.eu; h=cc :content-type:date:date:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to; s=fm1; bh=/e2HTv0KzoupVZhUA6KG19X0BHw4EmVOFxyf92 lVeME=; b=GyloiHOt9AFrA7MyrOOVJ75L8XWtMoAMY3l6kefMtLK+bndo8r/wra EEEPkS2roY8u2KfRrdGWRKN2duwxAYctiijpipB0tGl54LjgvFfgdhl7FLfKzqDP a4Y7fcqA1yxfyVpUsJ7gUjNk/656H5agbQxpPRodaHe9AzqhZCysh7bNauQBNndu R+5nTr0hgIKa02AYj6mb11aBNOntfkIysxQm7eYk/huIOX07ctVx5E2YoD/A5ePs ol/g7bj3bqyjENcg9W7bOhvA5gSlV4Z7o9I0iGfGuwNyULvoCvWOS8ch6rsx9P4f B8m4udrDrXieukatN48RpR3YVN6myvHQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:date:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:sender:subject:subject:to:to:x-me-proxy:x-me-proxy :x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=/e2HTv0KzoupVZhUA 6KG19X0BHw4EmVOFxyf92lVeME=; b=JW1uLrR32O1GFRagLEUK1RpAA+QIfsiCH laa67cIW+HsvkMV2lIv27UWQxMbTx48+OcIDEOABLgHZlMdvT4sMWKFZBzPganDy RJNHB4dm1Y1gWJQO9xJippr5CjzUYX0NpIO9AzR1yhBMoJBMDs1HTfY7oIfsIlU7 u/WHCe29KTqwDtOnueWbeqgFjopa/oEN24cBSVQIXaByG0OL6B3qd6uS2mfVS8YK yZ+TiMvIiNf7azUuqdeH9PdYftesPKXa/IZpmh+YWq4QyikLP8eXMFsn8X8gk31m gnQyHlCmgGiErdEdKE87Qoi1knuNdLysLEVBQCMpP5BIwOrddJPCw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvvddruddvkedguddukecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecunecujfgurhepfffhvffukfhfgggtuggjsehttd ertddttddvnecuhfhrohhmpeetnhhgvghlohcurfgrphgvnhhhohhffhcuoegrrghpsehp rghpnhgvthdrvghuqeenucggtffrrghtthgvrhhnpefghfeugfeiteeuvdfghfdugedvte elhfffhfevtdefudefvdetueetudetudegvdenucevlhhushhtvghrufhiiigvpedtnecu rfgrrhgrmhepmhgrihhlfhhrohhmpegrrghpsehprghpnhgvthdrvghu X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA for ; Mon, 14 Mar 2022 15:03:10 -0400 (EDT) Date: Mon, 14 Mar 2022 20:03:08 +0100 From: Angelo Papenhoff To: tuhs@minnie.tuhs.org Message-ID: References: <20220314165604.4889918C075@mercury.lcs.mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [TUHS] [tuhs] PDP-11 and early Unix 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 14/03/22, Clem Cole wrote: > > > > And a tip of the hatly hat for getting this: > > > > Although the ++ and - operators in C are equivalents of DEC and INC > > instructions, they were inspired by an addressing mode in the PDP-7. > > > As I said, the authors seem to have done a little homework, although I was > under the impression ??Ken?? had created them for B independently (which, > of course, was first on the PDP-7). The ++/-- for increment and decrement > was just a nice notation since they are such a common occurrence in real > code, it's handy to have. But, I did not think the PDP-7 ISA includes > addressing modes in the same manner as the 11. I'm probably confused, but > I thought PDP-7 is a very simple instruction (and small) with an AC, > Link/Indirection and a PC - it reminded me of the PDP-8 more than anything > else [although, IIRC it could do both 1's complement and 2's - depending > the type of AND instruction]. The PDP-7 has auto-increment registers at 10-17 that are incremented when addressed indirectly. I don't think it's even possible that the B runtime used them, because of the implied indirection, which is logically separate in B. They might still have been an inspiration, but i didn't get that impression from the copious discussion of that topic. aap