Revision 61140 of "Dadism" on enwiki

{{featured}}
-----

I suggest that, for the sake of clarity we use these terms throughout, pointing out the other sometimes confusing usages in a special para of its own.
* ''exchange building'' (=US "central office", UK "telephone exchange": can house switches, concentrators, or both)
* ''remote concentrator'' 
* ''telephone switch''  (=UK "telephone exchange", too, but being replaced in UK technical use by the US term, for reasons of clarity)

----
Ok - I spent 3 years in and about the BC Telephone system from 1969 to 1972 and the nomenclature at that time was something like:

* Exchange: 10,000 numbers denoted by common first 3 digits of a 7 digit number
* Central Office: where the equipment for one or more Exchanges lived
* Switch: the equipment used to implement an "exchange". Distance between COs was dictated by the physical characteristics of the twisted pairs used as trunks between offices - typically around 18,000-25,000' by cable (4-6 miles) in urban areas.


Since then I've been involved in specifying systems for a CLEC (1997) and things have changed - electronic exchanges and fibre optics have taken over and:

Switch: hardware capable of one or more sets of 10,000 (or in some cases groups of 1000) numbers, each of which  might be terminated in a "remote concentrator" many miles (100+) from the CO.

So, you see that the nomenclature changed with the time period.

comments?

----
During the mid 1980's to late 1980's in America in my hometown of Parma, Ohio, there was a "prank" which some people did at a public phone.  They would dial 555 then the last four digits of the phone number that appeared on the public phone.  Let the phone ring once.  Then they would hang up and leave.  This would then cause the phone to ring a few seconds later.  Of course no one was on the line.  This 555-test was also capable of being executed from a private house phone.  To the best of my knowledge this 555-test longer works as described.

Can other people please provide further details on the 555-test?

----
I removed the following because it's wrong:

"In [[1971]] the computerized switching system for telephone traffic was invented by
[[Erna Schneider Hoover]] and replaced existing hard-wired, mechanical switching equipment."

"Computerized" or stored program control (SPC) switching was put into practice as early as 1958 with the early ESS prototypes that Bell Labs made.  If one reads the Hoover patent (US Pat. No. 3623007) it can be seen that Hoover didn't invent SPC switching but rather came up with a method for process priority.  This is still used today and was an important development, however the above statement is wrong.

[[User:Sam Etler|sam]] 14:38, Sep 22, 2004 (UTC)
----
The section on topological sort needs to be rewritten.  I find it hard to understand (which is surprising since this is a featured article). -- [[User:Mordomo|Mordomo]] 00:23, 30 Nov 2004 (UTC)