KBK update for Monday, 16th December

The Micro Switch KB page has received a major update, based on the charts from Honeywell and the promotional literature scanned in by the Computer History Museum. The charts indicate that the reed switches provided both momentary and alternate action, as well as audible feedback in a single model, 7A1HW. Sadly, the specifics of the audible feedback arrangement are not available, as the relevant charts appear not to have survived.

The promotional literature (previously uploaded) also details the method by which KB provides self-encoding key stations: all switches are wired to a common bus, and the bus connections define an 8-bit identity for each switch.

The trombone slide below some switches is found to be a connection from the plunger through to the bailing and lockout mechanisms that can be installed on a lower row in the assembly. This arrangement is supported by the reed switches too, although this has yet to be seen.

As a note, the difference between black and grey shells for KB reed switches is now clear. Black shells are SPST momentary only, while grey shells support up to four poles, bail and lockout, alternate action and audible feedback. Although four poles are physically supported, the limit in all documented types is two poles.

The symbols on the shells seem to be the date codes for the reed capsules themselves.

View within the updates for 2019

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