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 10734 invoked from network); 1 Apr 2021 20:58:13 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 1 Apr 2021 20:58:13 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id A279C9CA42; Fri, 2 Apr 2021 06:58:11 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id A63F79C9A8; Fri, 2 Apr 2021 06:57:40 +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="hZBTwBKr"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id 6A0F59C9A8; Fri, 2 Apr 2021 06:57:36 +1000 (AEST) Received: from mail-qv1-f45.google.com (mail-qv1-f45.google.com [209.85.219.45]) by minnie.tuhs.org (Postfix) with ESMTPS id 9E13D9C8A5 for ; Fri, 2 Apr 2021 06:57:35 +1000 (AEST) Received: by mail-qv1-f45.google.com with SMTP id t16so1653807qvr.12 for ; Thu, 01 Apr 2021 13:57:35 -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=+QBXJ4j1KLdt74n5BB5baBGu/CQtjg2MyysX2eiY3SQ=; b=hZBTwBKrPPwYdAXGXF6NkVsTb1eUp/I2HjILndx0ZtL7iBLMo1n2BR2vwxAHQcAMiw vrLaAp1R9LpywctUyMZkrgWUT4Yv2xC+cUhLsgPsR3PyptQ0+9YGwisNeBKwuvfuEiWI 7mlVk3annI3J4INRRSi8/09YZqnya++5Vpk2D0HV8NZeBvm7iEUuwwRzi5oXp2EfSFc4 O94/rltP4j4C9j0kv16iYpyDqcLKdLWv1ihp4DBejvoNm6ttsITLtJgvuEZnsWrIEIjn oE+qtu0/a0ak4pWddT2MstY4RuLUlqkQHy4m0413cuAddtJA8gbYyWABashhOa8alAsP NsJA== 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=+QBXJ4j1KLdt74n5BB5baBGu/CQtjg2MyysX2eiY3SQ=; b=ckYm4kthumSkDorTev+l1Mf90lZIcDOIbBEVi7aADOapLjmSpdxrVAQ5WH9pTu10RC MrDH4QO9HGaUH+xPdHOQje/j19X5R8BQcpYbpOeALakZQNn13pbBCvyC3jsuAxChper5 /xSPtFjjXrklLo7GwbByg8h0VM+VFOCVHmGnwms10JDtU7gkMhSZMyJ++iCfZnY00QO0 x+Sq8wXljZ2sLD5/Ocpyc+EZl3ap3ucKbXxZAAoPpNHyL2ypYhi3uljFoAFsIuZ2so0O WT4H0v3SKrZi7nPG6JSGEmw4/zm+gwclg2oRPTtNCMEcX5mE/2Ym56oNgQ+nftaornT3 jSxA== X-Gm-Message-State: AOAM533C4mqMSCDuYLovtw3VoQgRSSK6Qab2JPB9rQ1r1g1uNJvvNK0r Mnmth0CQfdi9vFP5soELwPx/Mikv3BMcI5ApeoxeWREobD5RhwJj X-Google-Smtp-Source: ABdhPJxu7zNZ7eBul/202lvh7p9DMRguDTGJEXngwTynbt7l8y3Aa8DQIWl7t7Prmltq3F695EvrE6RN8TO1YhhoPBI= X-Received: by 2002:ad4:4e23:: with SMTP id dm3mr10169678qvb.4.1617310654717; Thu, 01 Apr 2021 13:57:34 -0700 (PDT) MIME-Version: 1.0 References: <20210401201211.97D7B18C073@mercury.lcs.mit.edu> In-Reply-To: <20210401201211.97D7B18C073@mercury.lcs.mit.edu> From: John Cowan Date: Thu, 1 Apr 2021 16:57:22 -0400 Message-ID: To: Noel Chiappa Content-Type: multipart/alternative; boundary="00000000000010ef7105beef7b84" Subject: Re: [TUHS] Data structures in Unix editors 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: TUHS main list Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" --00000000000010ef7105beef7b84 Content-Type: text/plain; charset="UTF-8" On Thu, Apr 1, 2021 at 4:31 PM Noel Chiappa wrote: > The first is a TECO from the fourth floor V6 machine (DSSR/RTS) at Tech Sq > at > MIT: > I happen to remember how PDP-8 Teco stored its content. In Teco, for those who have never made its acquaintance, there is the current buffer (which does not typically contain all of the current file) and a bunch of named Q-registers that store blobs of text. Since the PDP-8 is a 12-bit machine, the normal way to store ASCII uses three characters in two words: one in the low 8 bits of the first word, one in the low 8 bits of the second, and one in the top four bits of both words, split big-endian. In Teco, however, the current buffer is stored in the bottom 8 bits of a single 4KW memory field. The Q-registers are stored in alphabetical order by name (a single character) using the straddling top-4-bits method described above. Because the processor cycle time was the same as memory access time anyway, this storage method was perfectly adequate. You can also look at the source for Teco-C, which is available in several places on the net, the last I looked. John Cowan http://vrici.lojban.org/~cowan cowan@ccil.org Heckler: "Go on, Al, tell 'em all you know. It won't take long." Al Smith: "I'll tell 'em all we *both* know. It won't take any longer." --00000000000010ef7105beef7b84 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Thu, Apr 1, 20= 21 at 4:31 PM Noel Chiappa <j= nc@mercury.lcs.mit.edu> wrote:
=C2=A0
The first is a TECO from the fourth = floor V6 machine (DSSR/RTS) at Tech Sq at
MIT:

I happen to r= emember how PDP-8 Teco stored its content.=C2=A0 In Teco, for those who hav= e never made its acquaintance, there is the current buffer (which does not = typically contain all of the current file) and a bunch of named Q-registers= that store blobs of text.=C2=A0 Since the PDP-8 is a 12-bit machine, the n= ormal way to store ASCII uses three characters in two words: one in the low= 8 bits of the first word, one in the low 8 bits of the second, and one in = the top four bits of both words, split big-endian.

In Teco, however, the current bu= ffer is stored in the bottom 8 bits of a single 4KW memory field.=C2=A0 The= Q-registers are stored in alphabetical order by name (a single character) = using the straddling top-4-bits method described above.=C2=A0 Because the p= rocessor cycle time was the same as memory access time anyway, this storage= method was perfectly adequate.

You can also look at the source for Teco-C, which i= s available in several places on the net, the last I looked.



John Cowan =C2=A0 =C2= =A0 =C2=A0 =C2=A0 =C2=A0http://v= rici.lojban.org/~cowan =C2=A0 =C2=A0 =C2=A0 =C2=A0cowan@ccil.org
Heckler: "Go on, Al, tell 'em a= ll you know.=C2=A0 It won't take long."
Al Smith: "I'l= l tell 'em all we *both* know.=C2=A0 It won't take any longer."= ;

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