IBM announced the IBM System/360 on April 7, 1964. Shortly after, Mike handed me a new IBM Systems Journal that had articles by the System/360 architects — and holy cow, one by Ken Iverson, Adin Falkoff, and Ed Sussenguth that precisely defined the whole 360 line in 18 pages of Notation, plus commentary: “A Formal Description of System/360.”
Phil and I devoured it. Once past the steepest part of the learning curve, we gave a series of seminars to other students. I found a few typos, which I mailed to Ken.
Then Ken came to visit, touring several institutions to talk about the Formal Description and his notation. I listened, argued once or twice, and handed over my latest errata. Ken thanked me, and said “Larry, these are pretty minor. Why don’t you find something seriously wrong?”
Nothing could have fired me up like that challenge. I scoured the article. Late at night I sat in bed, with the fold-out pages resting over my recent bride’s nose (a nuisance) and eyes (appreciated). I got lucky. The Memory Access program had a race condition between requests from the Processor and Channel programs.
Next day at lunch I showed Ken what I’d found. Mid-afternoon
Mike came by my office. “Larry, Ken’s taking the Lord’s name in vain. He came back from lunch saying ‘That sonofabitch Breed! Why didn’t we talk to him before we published this god-damned thing?'” And I knew that I had to go to work for him.
Kurt W. Beyer has a really interesting analysis of IBMs position and literature concerning inventions in general and in particular with respect to Howard Aiken in his biography of Grace Hopper. (Aiken was Dr. Iverson’s advisor at Harvard). It was Beyer’s analysis which inspired my thoughts about what you are saying. I believe there are at least two forces pulling on APL with respect to credit and profit; those of a protective proprietary patent culture (beginning with IBM) and those values which evolved from mathematics which concern sharing scientific information for the advancement of humanity. APL certainly straddles both world views which is one of the reasons it makes such an interesting subject for a documentary.
I have never heard that IBM denies Dr Iverson as the inventor of APL but on the other hand, it would be uncharacteristic of that organization to give credit to any individual for a particular invention (thought they do have their “Fellows”).]]>
The IBM guys sent a deputation round to our research labs at Berkeley and to persuade us of the value of APL and i admit, it did prove handy for our time series stats.
IBM never mentioned anyone else inventing APL.]]>
Mr Hui – The funny thing is, every time I say anything critical about Dijkstra I get trouble from my dad!]]>
Ironic, isn’t it? As you know, Dijkstra was dead set against APL. (See for example this 1978 article by Perlis.) I’ve looked at some EWDs briefly, and as I was reading one I said to myself, “APL should be a natural for this guy!” Dijkstra was interested in writing provably correct programs, and APL programs are easier to prove correct than programs in other languages.]]>