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,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 25796 invoked from network); 25 Sep 2020 01:40:39 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 25 Sep 2020 01:40:39 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id D39309CEC9; Fri, 25 Sep 2020 11:40:38 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 7431E945A9; Fri, 25 Sep 2020 11:40:02 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ccil-org.20150623.gappssmtp.com header.i=@ccil-org.20150623.gappssmtp.com header.b="NRRToUp1"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id 5431D945A9; Fri, 25 Sep 2020 11:39:59 +1000 (AEST) Received: from mail-qt1-f169.google.com (mail-qt1-f169.google.com [209.85.160.169]) by minnie.tuhs.org (Postfix) with ESMTPS id CAC5D93D65 for ; Fri, 25 Sep 2020 11:39:57 +1000 (AEST) Received: by mail-qt1-f169.google.com with SMTP id n10so745882qtv.3 for ; Thu, 24 Sep 2020 18:39:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ccil-org.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=iEmWrWQMj5U/jgSSdn4QvlBuMBZr8ZBPzzKLG+bWTe4=; b=NRRToUp1va3SGXBamkNzIlyQm3t4io7kq2GqDpoZJPHJ46gDAtN0S25D3teLccPAap XJzvt6IRJfNjHWx7MTV8fFDpUbdcdVXFcPbTETR2hciyfXwx28RNFZRGipXW5q0TLwgn ZxTzJnS3vfX6XiZdbq2MXpk3R3X0sZ3u3p7o11WmJ4J0DAAp1wm3J0us1/c1X6XFAMqS U6hja8KfPXa2OGlkSbb06R3RJP/g5oXQfncM8CM415mVjMJUC4MVH3rnUv7xUlwK27CD oZ2CiGRms1rNniQVQpPX9CipZlfxG4K87RiIPYDCdIv6ALBTtU2DxKUWSaU0Kb0ydXrz 36Cw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=iEmWrWQMj5U/jgSSdn4QvlBuMBZr8ZBPzzKLG+bWTe4=; b=aiOZY0KmhmvBpynZ2QHr2mmHQ6XzHfLeuj4mf52JOcLzeUpFImOpNz28UkieN7umS/ 4sdyC1D6IWvdnpiCcc4KY7U6l3qGA2viaAY3wOEhIvotqXWNNxLOrh/X/bgeYYeWs6sO nHO4V9PpZ94BEq0G+KaB8OspZU+bvEvfSDGBGF11pg+DENprr7TIIOJCPTESv/LZJmcU dZurFPf/wqszGcSK8wnZyriB1oPhoVrEziae6Pjfevhme+21N/NLXErOuEKZ8dfKCPbg FstbKNBAB8hhl06lpkPJL6Uir0LUvbnNRQSWg1vtVyMW8rgazRRVwgmUUaFmfc7yiQ5Q aa6w== X-Gm-Message-State: AOAM5328S7wDdZM87HiY4YjAi0o1Jix2dXVcnvlXWqnwp39nPQADzVse ClYgfVizfcI8JmI3OWjSvx29RibCuwN928C3c1OaHw== X-Google-Smtp-Source: ABdhPJzlAq2j/GCjdPBP4xQ6itqlmdDlH1LRFYgoa8rbGPD7goEfPNCDOUYOE/SHzZRgKM+qZYrrXP2g9cDljsSeGt8= X-Received: by 2002:ac8:1a7b:: with SMTP id q56mr2239741qtk.56.1600997996855; Thu, 24 Sep 2020 18:39:56 -0700 (PDT) MIME-Version: 1.0 References: <202009190151.08J1pYnb066792@tahoe.cs.dartmouth.edu> <202009201842.08KIgn2f022401@freefriends.org> <04211470-AD63-452A-A0BB-6A7A6FD85AAE@gmail.com> <20200925001859.GC53226@eureka.lemis.com> In-Reply-To: From: John Cowan Date: Thu, 24 Sep 2020 21:39:46 -0400 Message-ID: To: Warner Losh Content-Type: multipart/alternative; boundary="000000000000e399b905b01964f8" Subject: Re: [TUHS] One's complement (was: reviving a bit of WWB) 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" --000000000000e399b905b01964f8 Content-Type: text/plain; charset="UTF-8" On Thu, Sep 24, 2020 at 8:22 PM Warner Losh wrote: Don't know about the others, but I'm pretty sure PDP-10 wasn't 1's >> compliment / was 2's compliment.. > > Correct. The PDP-1 (18 bits) was DEC's 1's complement machine. Its direct successors the 4/7/9/15 had both 1's and 2's complement arithmetic. The 12-bit 5/8/12 machines had only 2's complement, but retained the PDP-4 mnemonic TAD (Two's-complement Add). By the time the 36-bit 6/10/20 line was designed, it was clear that 1's complement was history, and the mnemonic was changed to ADD. (The PDP-3 was a PDP-1 with a 36-bit data path, and only one ever went into production; the PDP-2 was to be a 24-bit machine, perhaps a compromise between 6-bit and 8-bit byte systems, but was never even designed.) John Cowan http://vrici.lojban.org/~cowan cowan@ccil.org I marvel at the creature: so secret and so sly as he is, to come sporting in the pool before our very window. Does he think that Men sleep without watch all night? --Faramir --000000000000e399b905b01964f8 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


=
On Thu, Sep 24, 2020 at 8:22 PM Warne= r Losh <imp@bsdimp.com> wrote:<= br>

Don't know about th= e others, but I'm pretty sure PDP-10 wasn't 1's compliment=C2= =A0/ was 2's compliment..
Correct.=C2=A0 The PDP-1 (18 bits) was DEC's 1's comple= ment machine.=C2=A0 Its direct successors the 4/7/9/15 had both 1's and= 2's complement arithmetic.=C2=A0 The 12-bit 5/8/12 machines had only 2= 's complement, but retained the PDP-4 mnemonic TAD (Two's-complemen= t Add).=C2=A0 By the time the 36-bit 6/10/20 line was designed, it was clea= r that 1's complement was history, and the mnemonic was changed to ADD.= =C2=A0=C2=A0

(The PDP-3 was a PDP-1 with a 36-bit= data path, and only one ever went into production; the PDP-2 was to be a 2= 4-bit machine, perhaps a compromise between 6-bit and 8-bit byte systems, b= ut was never even designed.)



John Cowan =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0http://vrici.lojban.org/~cowan =C2=A0 =C2=A0 =C2= =A0 =C2=A0cowan@ccil.org
I marvel = at the creature: so secret and so sly as he is, to come sporting
in the = pool before our very window.=C2=A0 Does he think that Men sleep without
= watch all night? =C2=A0 =C2=A0--Faramir

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