Re: History--Bell toll routing machine cards--other applications? [telecom]
- From: hancock4@xxxxxxxxxxxx
- Date: Sun, 17 Feb 2008 11:08:38 -0500 (EST)
On Feb 16, 7:20 pm, klu...@xxxxxxxxx (Scott Dorsey) wrote:
Bell built as much as possible in-house, they built it to last, and they
ran it as long as they could, until it was more cost-effective to employ
something else. They did not push the envelope if they could avoid doing
so. Consequently, the telephone system was very stable.
Basically true.
But I wonder if other organizations, such as IBM or other computer
companies, made use of Bell card translator device. It looks like a
great random access read-only memory. I have no idea of its cost. I
think the capacity of it, even holding 1,000 cards, was not too high,
maybe roughly 15 numeric digits per card. I don't know the capacity
of magnetic drums of that era. One problem with drums might have been
patent rights, I think ERA/Univac owned them.
The first IBM disk drive held 5 million characters, obviously far far
more, and that was soon expanded to 50 million.
As to Bell doing everything in house, until the 1970s, this policy
made sense. Since Bell was totally responsibile (today we call "DBOM--
design build operate maintain) it was to their advantage that
maintenance be as cheap as possible and to max out the life of
equipment. Also, this meant high reliability in tough service, vital
for customer satisfaction. Unfortunately, in the 1970s some ancient
equipment was kept in service or not well maintained (letting line
finders fail in an SxS office was a disaster).
Also, for ESS development, commercial electronic computers did not
have the same reliability 24/7 that ESS required*.
Non-electronic business machines tended to have much longer lifespans
than electronic machines. This is ironic in that electro-mechanical
and mechanical gear have moving parts that wear out and need regular
service while electronics does not (other than the vacuum tubes).
The amount of effort to cut over a central office was absolutely
enormous. It's understandable this was deemed a rare thing to do.
Back in the 1950s and 1960s, even if a central office was 'left
alone', it actually wasn't. There was always wiring changes to
accomodate new trunking and routing and likely expansion of
subscribers. New features, like Touch Tone and DDD were added.
Bell did buy lots of PDP mini computers for various applications, both
in actual switching and administration. I forgot where, but I think
they used PDP computers (and IBM System/7) in upgraded AMA. I think
it was for the PDP that Bell developed "C". I think for customer
billing and general accounting they used the big IBM mainframes, but
for things like plant administration they used mini computers..
*I'd love to visit Morris IL and try to find if there's any newspaper
articles or documentation about the ESS experiments held there; such
as what the customers thought of it.
.
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