[inforoots] Origin of the IBM 1130 Name

[Mike Cheponis]

This note is from R. Tim Coslet:

The 1620 had Multiply as a standard instruction but Divide was an option. If you didn't have the Divide option, then
division was done in software.

Multiply had enough hardware support to manage look-up of 2 digit partial products then look-up the sums to accumulate
them into the "Product Area" @ 00099 (The multiply hardware automatically cleared the 20 digits of this area before
starting)

The Divide option consisted of 2 special instructions Load Dividend and Divide: Load Dividend loaded the "Product Area"
with a shifted version of the Dividend and Divide performed a repeated subtraction (with hardware counting the number of
subtractions at each digit position in the MQ register, then storing the MQ and advancing to the next digit position)
These two instructions were provided in both direct and immediate addressed forms. These instructions were a bit
difficult to understand.

Yes, there was some hardware support - but only just enough to make the table look-up algorithms work.

There was also a floating point option that provided both floating point multiply and floating point divide instructions
(if you had the Divide option) where the hardware provided support for the floating point scaling overhead using one of
the MARS registers as a counter and the "Product Area" @ 00099 as temporary floating point work area. If you didn't have
this option, then floating point was done in software.

Note: there are 3 known interpretations of CADET:

  1. Computer with ADvanced Economic Technology - Original interpretation according to e-Mail from Wayne Winger. leader of
     the 1620 design team.
  2. SPACE-CADET - "SPACE" was codename of 1401 and "CADET" was codename of 1620, both in development at same time.
  3. Can't Add Doesn't Even Try - Thought up by someone at San Jose after the machine was transferred there for
     production.

See the 1620 article on Wikipeda (I wrote most of it): http://en.wikipedia.org/wiki/IBM_1620

--
          R. Tim Coslet
          rtcoslet at rockwellcollins.com
          (408)-532-4505
          Rockwell Collins Display Systems




On Mon, 30 Oct 2006, Van Snyder wrote:

> Date: Mon, 30 Oct 2006 12:18:18 -0800
> From: Van Snyder <van.snyder at jpl.nasa.gov>
> Reply-To: Open Discussion about the history of the Information Age
>     <inforoots at computerhistory.org>
> To: Open Discussion about the history of the Information Age
>     <inforoots at computerhistory.org>
> Subject: Re: [inforoots] Origin of the IBM 1130 Name
> 
> =======================================
>
> Posts to inforoots at computerhistory.org is information known to or the opinions of the poster.  All posts to inforoots at computerhistory.org are archived.  By posting to this list you grant a license for use of this material to the Computer History Museum located in Mountain View, California, USA.
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> =======================================
> On Mon, 2006-10-30 at 07:34 -0800, Bill Worthington wrote:
>
>> I'm not sure what the logic was in selecting machine numbers back in
>> the 1960s.  There did see to be some order to it however.  I believe
>> that they were all assigned by the product marketing folks in White
>> Plains.  Development had their own names for unannounced machines like
>> NS, FS, Shark, etc.  (This was good because some of them never saw the
>> light of day.)
>
> I understand 1620 was called CADET, not because it was a beginner
> machine, but because it meant "Can't Add, Doesn't Even Try" (the
> arithmetic was done with lookup tables, with a little bit of hardware
> help for multiply/divide).  We had telemetry-processing applications on
> 1620's that changed the adder table to think in octal.
>
> I understand the 1400 series number came from the original 1400-
> character memory size.
>
> Of course, I could be wrong on both scores.
>
> -- 
> Van Snyder                    |  What fraction of Americans believe
> Van.Snyder at jpl.nasa.gov       |  Wrestling is real and NASA is fake?
> Any alleged opinions are my own and have not been approved or
> disapproved by JPL, CalTech, NASA, the President, or anybody else.
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