This restore/instructional video by means of the phone Connections Museum of Seattle options an excellent piece of electro-mechanical generation from the Nineteen Fifties — the 5XB hassle recorder. Museum volunteer Sarah the “Transfer Witch” has a deep pastime for outdated telephone apparatus, and provides a very good description of the difficulty recorder, the issues it solved, and the way it works, and the way they went about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 place of job switching was extra advanced and extra dense, the handbook strategies of removing faults was unmanageable. Semi-automatic approaches the use of hassle lamps, however even that had its limits. This “stack hint”, which can have loads 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 use of the to be had generation of the day, used to be a mind-boggling punched card equipment that punches over one thousand bits of knowledge 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 reasonably operating. However with a large number of endurance and get admission to to a provider handbook, the group ultimately were given it up and operating once more. Now the largest factor now’s getting new clean playing cards revealed when the few packing containers they’ve in any case run out.
If you have an interest in these types of intricate electro-mechanical techniques, do take a look at the video underneath. We particularly appreciated the mechanism that broke up 1200 bits right into a timed series of ten each and every 120 bits to power the punches the use of motors, cams, gears and relay contacts. You’ll be able to learn extra about this hassle recorder in this Bell Labs File technical record (pg 214) from Might 1950 (apparently, this factor leads off with Dr Hamming’s well-known paper on error detection and correction codes).