Re: FAA To Finally Ditch Floppy Disks & Win-95

On 6/14/25 7:38 PM, The Natural Philosopher wrote:

On 14/06/2025 17:34, Rich wrote:

c186282 <c186282@nnada.net> wrote:

On 6/13/25 11:35 PM, rbowman wrote:

On Fri, 13 Jun 2025 22:38:38 -0400, c186282 wrote:
>
>

     In any case it's become very clear that a major update is needed for
     the US airport/routing system. Knowing the govt process, the stuff
     will already be obsolete by the time it's installed, but not nearly
     SO obsolete.

>
In the early '70s we had a contract to build the controllers for the ALS
system. The heart of the controller was an Eagle Signal electromechanical
stepping switch which was pretty much obsolete. The harnesses had to be
laced since the FAA wasn't sure about those new-fangled nylon cable ties.

>
   Ooooh ! Nylon ! EVIL !!!   :-)

>
Not so much that as: Ooooh!, we don't know how well this new "tie"
method will withstand extremes of cold, hot and vibration, and the
current regs.  specify "laced" and we *do* know how lacing withstands
extremes of cold, hot and vibration.
>

   But yes, it's VERY typical for govt projects to be
   WAY behind the tech curve. The specs are writ, but
   then there's a HUGE delay in the implementation.

>

   The lunar-lander computer still used "rope memory"
   because of that - even though PROMS and erasable
   PROMS were widely available by the late 60s.

>
Also because (esp.  for EPROMS) the rope memory was much more radiation
hardened than EPROMS of the day were.  Also, for 'long duration'
projects such as that, often each component is designed and built, then
in the end the various parts are pieced together to produce the "flying
candle" you see on launch.  But the "computer" might have been designed
and built five years before that launch, and minus five years from
today might have meant no PROM or EPROMS were even available at the
time.
>

There is another issue I ran into. On an undersea cable repeater. IN 1988 or thereabouts the company was overjoyed to finally be able to use silicon, because up till the early 80s silicon simply hadn't been around long enough to be deemed suitable for long term use (>25yrs).
 Rope memory was tried and tested, Fusible link PROMS had no track record and EEPROMS were definitely subject to ageing

   I'd argue that fuse PROMS didn't NEED a 'track record'
   because they're SO straight-up. UV-EPROMS are also
   pretty stable (and NOT nearly so sensitive as some
   here suggest). EEPROM was more complicated. Most Flash
   is even more suspect.
   Even mag cores COULD theoretically be corrupted by
   a strong solar flare or, say, passing too close
   to Jupiter.
   You CAN still buy fuse PROMs. If you want it to be
   'forever' they're still a great choice.
   Various 'optical' versions of fuse-PROM and even
   EEPROM have been devised, though few make it
   to market. The underlying IDEA is something that's
   relatively difficult to flip states on by any
   common natural/unnatural means.