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A couple of years ago there were job ads for people to work on pdp11s in nuclear plants. Expected withdrawal date 2038, which is either the Unix time rollover or the plants lifetime.
One of the tek 1502s (b?) was specified in aircraft repair manuals. Somebody has built something new which duplicates the functionality and interface, and is apparently regarded as a dropn in substitute.
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While 1502s were used on aircraft they are diagnostic rather than calibration / certification tools so I'm surprised that there was a compliance issue.
I've actuall done quite well over the years buy supplying or repairing special to type or just specified TE that is otherwise obsolete.
If the maintence / overhaul manual says make ABCD Model 1234 TE and does not have the magic words "or equivilent" you HAVE to use that bit of TE or justify an alternative. There is a reference published by ARINC (formally Aeronautical Radio Incorporated) on how to show equivilence, ARINC Report 668-1, 70 pages of it. First you need the specifications of the original TE, a whole problem in itself.
This is not just paperwork for paperworks sake. The Lion Air 737 MAX accident was in part caused by an American company using different test equipment than that specified to repair the Angle of Attack (AoA) sensor. The company responsible lost it's FAA approval.
http://knkt.dephub.go.id/knkt/ntsc_aviation/baru/2018%20-%20035%20-%20PK-LQP%20Final%20Report.pdf