[time-nuts] Beaglebone NTP server

Jim Lux jimlux at earthlink.net
Thu Dec 11 09:59:39 EST 2014

On 12/11/14, 6:14 AM, Brian Lloyd wrote:
> On Thursday, December 11, 2014, Jim Lux <jimlux at earthlink.net> wrote:
>> Ah, but will the exact same single board computer be available for
>> replacement in 5 years?
> Most likely not. These days I can't imagine a manufacturer making the same
> SBC or mobo board for more than a year. If you consider BBB to be the
> logical continuance of the original beagle board then it is going on two
> years but is at rev C.
>> Or will it be Rev F instead of Rev B, with "just a few tweaks to improve
>> performance", but also enough that it's not "drop the image on it and run"
>> What about 10 years?
>> 15?
> If that is an issue, buy a spare and keep it in the same box with each
> running one. Heck, buy two spares.

I'm not sure that's a valid approach.. because eventually, the spares 
fail, or there's some crippling problem (year 2000 problems hardcoded in 
something, etc)

At JPL, we are somewhat cursed by the fact that we don't depreciate our 
test equipment and computers. It's expensed in the year you buy it, and 
then it is essentially free forever (subject to calibration and 
maintenance costs).

Therefore we have a lot of really old equipment around, and new systems 
are designed and built incorporating the old equipment.  But when the 
last unit of that old model fails, now you have to update everything and 
jump multiple generations at one time, which is difficult. You've got a 
lot of learned history and designs that rely on idiosyncracies of a 
particular model (e.g. the 8663A, which happens to do phase continuous 
sweeping and can be phase modulated directly).

And now, your venerable 8663 fails.

The new replacement model (e.g. the E8663B) is functionally quite 
similar, has all the same specs (maybe even better in some cases), but, 
oops, it doesn't do phase continuous sweeping (because the synthesis 
chain is different).

Rather than figure out how to solve the need with the newer gear, this 
leads to a scrounge fest.  You get the institutional inventory and 
surplus list out and start calling up people who have seem to have 
another 8663A that hopefully they're not using and/or that it actually 
We've got stacks of dead 8663s sitting around, in, I think, the forlorn 
hope that someone will be able to cannibalize them for repair parts.

The problem is even worse with PCs, because the support cycle time is 

The wailing, gnashing of teeth, and pulling of hair when NT 4.0 and 
later WinXP was declared OS non grata was amazing. Data acquisition 
systems, lab controllers, etc. all running WinXP and connected to the 
network as part of their function.  Upgrading your software from NT to 
WinXP to Vista then to 7 then to 8 isn't as painful as jumping from NT to 8.

Linux isn't a whole lot better. If you have a system you cobbled 
together in 2004 that was tied, say, to the typical audio system of the 
time, odds are that you're in for a real challenge to drop it into a 
modern distro with modern motherboard hardware.  Which version of glibc? 
OSS audio? parallel port drivers? Oh, your new mobo doesn't HAVE a 
parallel printer port?

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