This restore/educational video by means of the phone Connections Museum of Seattle options an excellent piece of electro-mechanical era from the Fifties — the 5XB bother recorder. Museum volunteer Sarah the “Transfer Witch” has a deep hobby for previous telephone apparatus, and offers a very good description of the difficulty recorder, the issues it solved, and the way it works, and the way they went about solving it.
As central workplace switching changed into extra complicated and extra dense, the handbook strategies of removing faults changed into unmanageable. Semi-automatic approaches the usage of bother lamps, however even that had its limits. This “stack hint”, which may have masses of signs, needed to be frozen whilst the technician recorded the standing on a sort. If every other fault got here alongside all the way through this time, it used to be misplaced. The answer, the usage of the to be had era of the day, used to be a mind-boggling punched card equipment that punches over one thousand bits of data when an switching error is detected or when more than a few watchdog timers expire.
The difficulty recorder within the Connections Museum used to be now not fairly running. However with numerous endurance and get admission to to a provider handbook, the crew ultimately were given it up and operating once more. Now the largest factor now could be getting new clean playing cards published when the few containers they have got in the end run out.
If you have an interest in these types of intricate electro-mechanical methods, do take a look at the video underneath. We particularly appreciated the mechanism that broke up 1200 bits right into a timed collection of ten each and every 120 bits to pressure the punches the usage of motors, cams, gears and relay contacts. You’ll learn extra about this bother recorder in this Bell Labs Document technical document (pg 214) from Might 1950 (curiously, this factor leads off with Dr Hamming’s well-known paper on error detection and correction codes).