On 21/03/2014 22:57, Alan Bourke wrote:
http://ask.metafilter.com/257424/Why-are-airline-computer-reservation-systems-so-slow#3741374
In the early seventies I worked on a tour operator reservation system
for KLM (flights *and* hotels!). Most of the senior design and
programming staff were ex BA and the whole thing was based on IBM's ACP
(Airline Control Program) presumably either a pre-cursor or a wrapper
for the 'TPF' mentioned in the link. It was all macro assembler and had
its own file system of fixed length header records (e.g. PNR header)
with double chained links (physical disk addresses) to child records. It
ran at around 95% of the theoretical maximum speed of the underlying
hardware.
It was one of the most complex non-military systems in existence but
there weren't 'millions of lines of assembler code' - the airline
industry was afaik the first to install the unprecedented and staggering
amount of 1 million bytes of *core* memory and the whole thing ran too
fast to allow paging for real-time tasks.
The mainframe was fronted by a specialist hardware telecoms and message
queueing system that cost more than the mainframe. Input was via 2260
terminals (3270's came later and had color!). Non real-time (Batch)
processing used hyper tape drives using 'squirrel cage' motors which had
windings of pure silver wire weighing a few grams which could go from
10,000 rpm forward to ditto backwards in 1/4 second. Things were *
engineered* in those days!
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