Message from discussion 360/20, was 1132 printer history
Received: by 10.66.86.6 with SMTP id l6mr3269856paz.11.1353353293182;
Mon, 19 Nov 2012 11:28:13 -0800 (PST)
From: Dan Espen <des...@verizon.net>
Subject: Re: 360/20, was 1132 printer history
Date: Mon, 19 Nov 2012 14:28:12 -0500
Organization: A noiseless patient Spider
Injection-Info: mx04.eternal-september.org; posting-host="960b39603e44c0554faedf0065e3beaf";
logging-data="27814"; mail-complaints-to="ab...@eternal-september.org"; posting-account="U2FsdGVkX1/MaAFrLO14WN1BWzVQONkqmoIyImzbcCY="
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux)
Content-Type: text/plain; charset=utf-8
> On Nov 19, 11:29Â am, Dan Espen <des...@verizon.net> wrote:
>> Hmm, there never was a follow on to the 360/20.
>> It was programmed in RPG.
>> I wonder what IBM was thinking when they decided to create a new
>> architecture instead of build another small 360-like machine.
> The issue was cost and attracting low-volume customers.
> Per the IBM history (System/360)--the System/3 was originally
> conceived as a low cost punched card computer. They saved money on
> the S/360-20 by using serial card readers (instead of more costly
> parallel readers*) and punch and an abbreviated instruction set (37 in
> the model 20 vs. 143 in S/360). But the S/360-20 still wasn't cheap
> enough for the lowest users.
> System/3 reduced costs further by using a miniature punched card and
> other smaller units. It had only 28 instructions.
> The S/3 "constituted a candid concession that S/360 could not bridge
> thw widening opportunities in the marketplace, at least not with the
> technologies available at the time."
> The S/360-20 basic machine rented for $2,000/month. The S/3-model 10
> basic model rented for $1,000/month.
> *Tab machines used parallel reading, which fit their functionality.
> But that was more expensive to accomodate in a computer which used a
> character format. Going to serial card readers and punches saved
> machinery and electronics at the cost of speed.
A serial reader could have been put on the 360/20.
So, 37 instructions vs. 28 justified a whole new architecture?
A bit strange.