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 22050 invoked from network); 3 Feb 2021 14:55:52 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 3 Feb 2021 14:55:52 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 9EB0C9C8E8; Thu, 4 Feb 2021 00:55:48 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 8FA2D9BA43; Thu, 4 Feb 2021 00:55:32 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=dartmouth.edu header.i=@dartmouth.edu header.b="jkKfTUdq"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id 9A1319BA43; Thu, 4 Feb 2021 00:55:30 +1000 (AEST) Received: from mail-wr1-f43.google.com (mail-wr1-f43.google.com [209.85.221.43]) by minnie.tuhs.org (Postfix) with ESMTPS id 737109BA40 for ; Thu, 4 Feb 2021 00:55:29 +1000 (AEST) Received: by mail-wr1-f43.google.com with SMTP id p15so24612523wrq.8 for ; Wed, 03 Feb 2021 06:55:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dartmouth.edu; s=google1; h=mime-version:from:date:message-id:subject:to; bh=U9l7K44V0P/BmQNjuyI6bdnUWXvei5vaV+UNqrZQsg4=; b=jkKfTUdqNOTQGH6SdXosGnz5a4lRSUtxfO2yvRj6PeqXDCsH8oERoKSxDtAAm/MilE /D9INMrxPfQUkUM0AdDIMTBRCNC6rdSBGvXHZ58LxcebBh3rpR4AQ2BBLyMBfxZB2g/P Q2ZNcEU6LpP1f9IHSivkqlooK3vFLNP+kHPUo1kMu/b9X3qNqnS0ngwXtUkd7SWQLB47 hrTuW7dKB9zvN1PTIlbvU6bcDk/G8a1J4hqJmxdGCOZVjHPsZ+Q5ne3uFrBrtBmtKc4j jSHwrUA6NQyai5InDMMYp7o5OG3MYwd6pNkY1C5eJn3dsZjhlFSdRaXHpX5/OBhgai1r kwVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=U9l7K44V0P/BmQNjuyI6bdnUWXvei5vaV+UNqrZQsg4=; b=KvAxgFN6aF+CR0IG33n1dnoDrJbNFvQocawoeCl12thNCqmESB09XPOx8hY/ny97Wf naobeaq3yfrIhNjZwUFTDTh8pi2RFyYSVxSfTYrGWxqAh2f847j55nlBAX7CyZylPibL ayVYYH4ztNPQmnUw9jHuYxdn8rO2QCv9vN0CD/8wPas47+yAmxVDn9FoTLOWlXjfhACE 4MdzDF7eFNqQOLT7w1k2zAOD/v8j6iXx0E0Jv4CmdXJzE68NG5zhL62+us+UDN26lD3L lppWwvQmAUNhw/2r0bxWWuMbTwoRyNlDMwQj4m12YfI/EMyZK3LXvUHwYkgyBkE8lA1U 8oFw== X-Gm-Message-State: AOAM532FeKwr+WwNO8ZaA6os8Mfog7v8qLhrmlReypYbzWUxTTKfJkK7 ajTVdb1Tfy1rTAHK/weNnDmHA2Z06F0mIPYB0+VnJVP9gG9fdA== X-Google-Smtp-Source: ABdhPJz671x130qWoPMwVHC5DN0VXz6M+uA5JjzE1MrAa+Ag4IKm/B7fSrriXN6TiWVAjGDGGTlgvMGt3Bx3sneORbk= X-Received: by 2002:a5d:4a0d:: with SMTP id m13mr3970039wrq.395.1612364128025; Wed, 03 Feb 2021 06:55:28 -0800 (PST) MIME-Version: 1.0 From: M Douglas McIlroy Date: Wed, 3 Feb 2021 09:55:13 -0500 Message-ID: To: tuhs@minnie.tuhs.org Content-Type: multipart/alternative; boundary="000000000000198f7e05ba6fc7ee" Subject: [TUHS] 2^n-bit operands (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: , Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" --000000000000198f7e05ba6fc7ee Content-Type: text/plain; charset="UTF-8" > Does anyone know why the computer industry wound up standardising on 8-bit bytes? I give the credit to the IBM Stretch, aka 7030, and the Harvest attachment they made for NSA. For autocorrelation on bit streams--a fundamental need in codebreaking--the hardware was bit-addressable. But that was overkill for other supercomputing needs, so there was coarse-grained addressability too. Address conversion among various operand sizes made power of two a natural, lest address conversion entail division. The Stretch project also coined the felicitous word "byte" for the operand size suitable for character sets of the era. With the 360 series, IBM fully committed to multiple operand sizes. DEC followed suit and C naturalized the idea into programmers' working vocabulary. The power-of-2 word length had the side effect of making the smallest reasonable size for floating-point be 32 bits. Someone on the Apollo project once noted that the 36-bit word on previous IBM equipment was just adequate for planning moon orbits; they'd have had to use double-precision if the 700-series machines had been 32-bit. And double-precision took 10 times as long. That observation turned out to be prescient: double has become the norm. Doug --000000000000198f7e05ba6fc7ee Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
> Does anyone know why the comput= er industry wound up standardising on
8-bit bytes?

=
I give the credit to the IBM Stretch, aka 7030, and the Harvest = attachment
they made for NSA. For autocorrelation on bit streams-= -a fundamental need
in codebreaking--the hardware was bit-address= able. But that was overkill
for other supercomputing needs, so th= ere was coarse-grained addressability
too. Address conversion amo= ng various operand sizes made power of two a
natural, lest addres= s conversion entail division. The Stretch project also=C2=A0
coin= ed the felicitous word "byte" for the operand size suitable for c= haracter=C2=A0
sets of the era.

With the= 360 series, IBM fully committed to multiple operand sizes. DEC
f= ollowed suit and C naturalized the idea into programmers' working
=
vocabulary.

The power-of-2 word length had th= e side effect of making the smallest
reasonable size for floating= -point be 32 bits. Someone on the
Apollo project once noted that = the 36-bit word on previous IBM
equipment was just adequate for p= lanning moon orbits; they'd
have had to use double-precision = if the 700-series machines had
been 32-bit. And double-precision = took 10 times as long. That
observation turned out to be prescien= t: double has become the
norm.=C2=A0

Dou= g

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