Re: A Silly Database Question

paul c wrote:
Walter Mitty wrote:
"howfie" <yadayada@xxxxxxxxxx> wrote in message news:Xns9C31ABF92C6E6yadayadayabloocom@xxxxxxxxxxxxxxxxx
Hi Paul,

Thanks for the info. With pictures like this,
http://www.columbia.edu/acis/history/cell2.jpg,
I guess it's easy to see why it's always a can or a cylinder.
...


Some other comments: The use of multiple platters was an attempt to increase the probability that more 'record's would be 'found'/accessed by a single head seek (the seek is along an imaginary radius of the platter). This is reminiscent of the engineering that was being added to jet airplane engines in the same period, many features added that had nothing to do with the original concept but rather with physical limitations and side-effects. Somewhere there is a great article about the complications of the jet engine for social and ergonomic reasons written by a Harvard professor, it is more humanist than most of what comes out of that business school.


Also, the programmable controllers contained some Buck Rogers concepts that have since gone by the wayside. The electronics for each disk head assembly treated certain cylinders (multiple vertical tracks), as 'special'. So there was a physical index of the 'file' locations record in designated 'tracks' of iron oxide. In the IBM world this was known as the VTOC/Volume Table of Contents. I had one boss who said if he read one more resume of a system programmer who had invented a new VTOC manipulation program, he was going to puke. This is some of why I wish I were born later, I remember getting assigned to write some disk access routines for a company branch in South America. They didn't want to use the generic subroutines for disk access provided by IBM which had memory sizes of thousands of bytes because they were short of 'main memmory' and it was too expensive to bump their main memory from 16Kilo-bytes. Whereas 'channel programs' of less than a hundred bytes would suffice to squeeze their application into the available memory. 'Virtual'/hardware 'paging' memory required buying a new cpu but even with paging, there were always high-use routines that one wanted kept in memory at all times. It seems a lot of the 'system' programmers from those days are still alive and as busy as ever on usenet. They can tell you a lot more than I can, see the alt.folklore.computers usenet group.


I think everybody interested in db should remember that the somewhat seminal System R IBM group was heavily influenced by the limitations of the hardward ot he early 1970's. It might be good thesis topic for some bright kid to examine the way db history has been influenced by this, rightly or wrongly. Seems important to me to remember that we might be in quite a different position if hardware developments had occurred in a different historical order.
.

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