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=DKIM_SIGNED,DKIM_VALID, HTML_MESSAGE,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 14518 invoked from network); 25 Sep 2020 15:31:41 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 25 Sep 2020 15:31:41 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 267D89CEDE; Sat, 26 Sep 2020 01:31:40 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 2CB4E94552; Sat, 26 Sep 2020 01:31:06 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=pass (2048-bit key; unprotected) header.d=bsdimp-com.20150623.gappssmtp.com header.i=@bsdimp-com.20150623.gappssmtp.com header.b="ZwjhHNEk"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id F156994552; Sat, 26 Sep 2020 01:31:02 +1000 (AEST) Received: from mail-qv1-f49.google.com (mail-qv1-f49.google.com [209.85.219.49]) by minnie.tuhs.org (Postfix) with ESMTPS id 609CE93D65 for ; Sat, 26 Sep 2020 01:31:00 +1000 (AEST) Received: by mail-qv1-f49.google.com with SMTP id cr8so1548304qvb.10 for ; Fri, 25 Sep 2020 08:31:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=QU7RATJ/APq00ClgQctDSvL1ApsPIl5aOVcjFaSFW3k=; b=ZwjhHNEkh4JvN2T7N7Q6IS2hJj6Jz5Jr1sFPAUC6jIOR8RyMU+7gQsComOCV+bI1Uy bW6/w+vth5KkXGdtlnciYNNF+eznwWq+sYzg8QNmTVpBpo6VZEw6DVS9SFwhyfB0mRWm ShhHdznNvrGE8F4Ov7aC8zQnyBuRZr8rsU4oVeuqgTC8IM5f71AYJhOv1/niM2LsUyPK bggNrMjgav1N/t9nYsdNH2/H8fyeAdpZpf2ETpfEZZvJQv/2fOxWYzTEihNdcI5fb4Hu qYx8anVw14gaTWR2CQN619pGxfqE0jQbzZ8FqsHsm6L4kGw2ylTCadA3a/lNjQOTvMWm mP+A== 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=QU7RATJ/APq00ClgQctDSvL1ApsPIl5aOVcjFaSFW3k=; b=sHNSG1arHI32wnetjMoJCXc8T/HZ0rQomzpvgV87HFfPh7YJ9ovi1qK5X/bepVPUl5 Udmnd2hZQzAw9jWhQrUphiHTTrgLb7Rxtv7WYgsWaeMpNk07+zg7+KymFZeAhER3npdG s+ys9G00BxXsCwkvAQVTPG28phfhuMHU7wHQ9XBbQAZ4biU0+kkMibfZL3YG+7wuMJzH pJHOhiniNYTEjgO+HaufoscZjfPAM24VkLdBw1C9Un7H/Zsoc7mmf17/uDGPTCfU+E3E dpfgRxT8HRn0HdsAqbcFOGuyJAgEjqtY9LMvHFB28rUAZy403d+DNd+Zd/VeYPve88lj LlTQ== X-Gm-Message-State: AOAM533MzBcbjem+NbVqhW99VmRS5pgS79hUNPCEmWoMSrbFtdMSAJfT tlOdqDWaEEDmpKWCB4f+JnEME7Ptx12t/2EeC0qQP2f1tVSQtw== X-Google-Smtp-Source: ABdhPJwU/Lrc06rhupg+FJajMiAcA6e5fhWeAP73dzpUUuen74HlTmZ0uhHXQswhk0/yAQo/8hRm9GK/9YMnkkGZvGo= X-Received: by 2002:ad4:4a6b:: with SMTP id cn11mr5194331qvb.53.1601047859236; Fri, 25 Sep 2020 08:30:59 -0700 (PDT) MIME-Version: 1.0 References: <20200925152108.2AD1218C0C1@mercury.lcs.mit.edu> In-Reply-To: <20200925152108.2AD1218C0C1@mercury.lcs.mit.edu> From: Warner Losh Date: Fri, 25 Sep 2020 09:30:46 -0600 Message-ID: To: Noel Chiappa Content-Type: multipart/alternative; boundary="000000000000eb28e105b0250071" 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" --000000000000eb28e105b0250071 Content-Type: text/plain; charset="UTF-8" On Fri, Sep 25, 2020, 9:22 AM Noel Chiappa wrote: > > From: Warner Losh > > > I'm pretty sure PDP-10 wasn't 1's compliment / was 2's compliment.. > > Just to confirm, I pulled out my PDP-10 Hardware Reference Manual; Vol I - > CPU > (EK-10/20-HR-001), and it does indeed say (pg. 1-12): "The fixed-point > arithmetic instructions use 2's complement representations to do binary > arithmetic." Selah. > Back in school, we had our machine organization course. When we learned about 1's complement, the professor said "I've used a lot of machines that had this. You will likely never see one with it. There are no operational machines on campus with that." It stuck with me. We had a TOPS-20 machine... the odd turn of phrase was due to a professor that had a board of unknown origin hanging on the wall that was a rumored to be a CDC or similar... ah, the mid 80s... Warner > --000000000000eb28e105b0250071 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Fri, Sep 25, 2020, 9:22 AM Noel Chiappa <jnc@mercury.lcs.mit.edu> wrote:<= br>
=C2=A0 =C2=A0 > From: Warner Los= h

=C2=A0 =C2=A0 > I'm pretty sure PDP-10 wasn't 1's compliment= / was 2's compliment..

Just to confirm, I pulled out my PDP-10 Hardware Reference Manual; Vol I - = CPU
(EK-10/20-HR-001), and it does indeed say (pg. 1-12): "The fixed-point=
arithmetic instructions use 2's complement representations to do binary=
arithmetic." Selah.

=
Back in school, we had our machine organization cou= rse. When we learned about 1's complement, the professor said "I&#= 39;ve used a lot of machines that had this. You will likely never see one w= ith it. There are no operational machines on campus with that." It stu= ck with me. We had a TOPS-20 machine...=C2=A0 the odd turn of phrase was du= e to a professor that had a board of unknown origin hanging on the wall tha= t was a rumored to be a CDC or similar... ah, the mid 80s...

Warner
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