No idea. Nowadays, the last mile (or "last few blocks" :> ) are often implemented with a mix of technology. SLIC96's, etc. Neighbor's new "land line" is just "a cell phone that isn't portable" (i.e., wireless device with tip and ring connections).
I (passively) "collect" old WE phones but not for their value
I think if you've got copper to the CO, you're pretty "safe" (funny choice of words). But, more and more of TPC's infrastructure is becoming hybridized so that "pair" you see may not actually correspond to another "pair" in the CO!
Yes, it always "made sense" to have a tone/pulse switch on a PUSHBUTTON phone -- as not all lines were DTMF-enabled (it used to be an "extra charge").
In school, a buddy recounts getting a phone call from TPC early one morning (perhaps timed to catch him half asleep? You know how early college students like to roll out of bed... :> )
She simply asked one question (which immediately tipped him off that there was an ulterior motive, here): "Could you please PRESS one on your phone?" At which point, he reached over to *another* phone and DIALED one (as the phone he was using to answer the call was a touchtone phone -- and he wasn't paying for touchtone service!).
I'm wwaiting for TPC to take the same attitude regarding CID (i.e., provide it universally and just only charge those folks who actually claim to want it!)
For a long time, they charged extra for tone dialing, maybe $2 or so a month. But internally they have to convert pulse to tone, so most often tone works anyway.
As far as I know, pulse still works. I don't have many actual dial phones, though. I do still have one I bought from Radio Shack (I think birthday present, actually) around 1974. That is, before the legality was completely worked out.
In software, if you build an application in an interpreted language, you have to deal with making sure that all your users have a working copy of the interpreter. Depending on the language and user base, this may range from incredibly painful to only mildly painful.
It is getting better over time as disks get bigger, networks speed up, and installers get smarter; it is more likely that the user already has some version of the interpreter around, or that downloading the intepreter doesn't take too long, or that installing a new version of the intepreter won't break everything else.
In modem days, people used to groan when they got their first application that required .Net, because that meant a long download of the .Net runtime from Microsoft. Eventually Microsoft started bundling the runtime with Windows.
If you spend more development time on using C or C++, and pick your calls very carefully from the Win32 API, you end up with an .exe that works on anything from Windows 95 to Windows 7. It won't *look* as pretty as a .Net application on Win7, but it will *work*. The problem with this (besides time) is that you probably have to have started developing when Win95 was new to even know where to begin doing this. :)
Similar considerations apply to Java, Flash, etc. Some things like Perl and Python have Windows interpreters available, but their functionality can be different enough from the Unix version to cause problems.
How about mechanical seals vs packed glands on pump rotary shafts?
The cost to design and develop mechanical seals originally was astronomical but for the cold war submarines and space race might not have happened. Now they are everywhere and modern vehicles no longer dribble their vital fluids onto the road. The difficulty was in persuading the new markets to accept the unfamiliar devices as OK.
Or maybe the plastic hose clips designed to be backwards compatible with the old metal jubilee ones. Designing kit for mass production almost invariably costs a lot more up front.
Oh my; so many places to begin. Vaccines; other (fancy) drugs; orthodontia; computer networks; catalytic converters; any major software package; Torx bolt heads; modern refrigeration in the home; PDA's; any disruptive technology.
Too easy to get buried in selecting examples that are reasonably relevant to your main topic.
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