Talk:IBM 407

Merge IBM 421
http://www.columbia.edu/cu/computinghistory/tabulator.html lists IBM 407 Accounting Machine 	High-speed alphanumeric. 421, 444, 447 variations. Wikipedia doesn't need an article for each. 69.106.238.83 (talk) 23:01, 30 December 2012 (UTC)

Multiplication on the 407
I entered into a discussion with another former tabulating machine technitian concerning the subject of multiplication on a 407. Clearly the old 407 manual does not address this, but it is my recollection that we were able to achieve multiplication through a technique that worked, although very time and resource consuming. It seems to me that the multiplier had to be store and compare against a counter that re-added the multipican for each integer in the multiplier. I don't recall how the cycles were acquired for the operation though.

The discovery of this technique was made by a fellow 685xx techncian in our USAF shop back in 1964. Needless to say, that was 40 years ago and my memory is not very clear after all these years. Does anyone have a better recolleciton about this technique than I do? Any help will be appreciated. YORD-the-unknown 21:13, 12 October 2006 (UTC)


 * and (unfortunately, what we want is in the referenced documents). From that same old tech 69.106.232.37 01:22, 13 October 2006 (UTC)


 * Excellent!! Unfortunately, I don't have an active ACM membership so we'll have to wait until someone comes along with one.  I'd really love to see the material. :)


 * Another Columbia reference I found: "Although the 407 is really just a big adding machine, creative use could be made of the control program; for example, as described by Roger L. Boyell in Programmed Multiplication on the IBM 407, Journal of the ACM, Volume 4, Number 4, October, 1957, pp.442-449."


 * It looks like our top guy learned the technique elsewhere and taught it to the rest of us.


 * That same guy programmed a 407 as an "alarm clock" one night on the grave shift, when it reached the designated time it started printing full 100 print positions and gang punching 80 column cards, cycle after cycle -- the thing made a hell-uva-lot racket, but I had to wake Cal up because he was out stone cold and the thing wouldn't stop. He hadn't gotten much sleep before starting the shift and didn't want to get caught asleep by the morning crew.  Here is another interesting reference.


 * BTW, I do recall that we had one E8 in our bank of 407s but we didn't have a 1620. Ah, the memories! YORD-the-unknown 10:08, 13 October 2006 (UTC)


 * Concerning the division operation. I'm getting the impression that it was not doable.  Here is a link to an IBM page that lists multiplication but not division.  It looks like my assumption that if multiplication could be performed that division could also be performed was not a good one.  Subtraction had the feel of a bit of a kludge already, so I'm not surprised.


 * Concerning Multiplication it was possible and there was a diagram in the later IBM Manuals for the schematic required to make it work. I remember in 1972 when one of my fellow students followed it exactly and the diagramed solution did not work.  It was a series of adding and carrying over busses and repeaters to add the first value the number of times in the second value represented.  As I say he had the board wired exactly how the diagram showed and asked me to look at it.  We worked it over logically and found one place where the logic broke down. I rewired it a little and we got it working. We could not run it much since the repetition was such that it overworked the mechanics and heated up the machine.  But it did work and the results were correct.  We multiplied a four digit number by another four digit number with the correct results.  — Preceding unsigned comment added by LivinInTheUSA (talk • contribs) 19:29, 28 December 2015 (UTC)

Was it still plugboard programmable when used with the IBM 650
When used with the IBM 650 was it a standard/original 407 or what changes were made ? - Rod57 (talk) 13:19, 10 January 2016 (UTC)


 * @Rod57 I haven't found any manuals on-line that discuss this in detail. I presume the connection was similar to how the 533 worked, though I where there were enough extra hubs on the 407 plug board. This IBM history document says the 407 was attached by a cable and that the 650 could use the 407 to both print documents and read cards and punch cards too if a summary punch was attached. The document says that the changes did not interfere with the 407's normal operation: https://www-03.ibm.com/ibm/history/exhibits/650/650_tr1.html

Overclocking
I removed the following comment and restored the original text:


 * "the following text is correct, but is describing how to steal - paying rent for a slower machine but then altering it to run faster. Such descriptions are not generally seen in Wikipedia articles.  Is there any reason for including this?  -- It was possible to insert a folded card between that relay's contacts to "overclock" the slower model to the faster speed."

I think this detail is of historic interest and an early example of overclocking. Whether it was legal or ethical is a topic that would require a reliable source to discuss in the article. There was a similar situation with the IBM 1130 model 4, which was deliberately slowed down to sell at a lower price point, but there were ways to speed it up, and the possibility is discussed in that article. --agr (talk) 16:16, 4 April 2016 (UTC)


 * ftp://public.dhe.ibm.com/systems/support/warranty/pdfs/v13/Z125-4753-13_en_US.pdf
 * "IBM warranties will not apply if there has been misuse, modification, damage not caused by IBM, failure to comply with instructions provided by IBM, or if otherwise stated in Part 3."
 * I envy everything you write - except this. 73.71.159.231 (talk) 07:13, 18 April 2016 (UTC)

Picture shows machine in an inoperative state
I put this comment on the talk page for the picture. Posting it here in hopes of more (any) response:

The picture shows the control panel (patch panel) gate in the "open" position, where it would be just prior to removing the panel. In this position the plugs on the control panel will not make contact with the receptacles in the machine and so the machine will not function. Yet the operator is inspecting the printed output and has a finger near the button panel, as if ready to stop the machine. How does this make sense? Jeh (talk) 09:26, 18 April 2016 (UTC)