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Micro Switch RW Series



RW Series is a series of keyboards from Micro Switch, which use KB reed switches. These were classified as Micro Switch’s Phase II keyboards, with the self-encoding KB keyboards being phase I, and phase III representing the Hall effect keyboards. The introduction details for the reed keyboards are a little confusing. An article in Electronics magazine from September 1968 states that the KB reed switches were introduced in 1966, while a 1970 Micro Switch advertisement states that reed keyboards were introduced in 1965 and solid-state-encoded reed keyboards were introduced in 1967. The September 1968 article claims that reed switch keyboards were introduced in 1967, and Phase II solid-state-encoded reed keyboards were introduced in 1968 (earlier in the same year that the Hall effect keyboards were introduced). Advertisements for solid-state-encoded reed keyboards—which were not named—appeared at the end of 1967.

Product Sheet 51RW was mentioned in Computer Design, March 1969, which is too late to help with date information.

Keyboards seemingly produced by customers that used KB reed switches date back to around 1966–1968, in line with when the reed switches appear to have become available. It appears that the use of these switches in keyboards was fairly short-lived, with Micro Switch instead pushing SW Series solid state keyboards that were introduced in late 1968.

Via his son Scott, Everett Vorthmann from Micro Switch has indicated that “RW” denotes wired reed keyboards, i.e. fully-assembled keyboard units with reed switches.

Series KB switches could be soldered to printed circuit board, hand-wired onto notched terminals, or connected via spade connectors. Third-party keyboards tended to use spade connectors and hand-wiring, while Micro Switch RW keyboards appear to all use PCB assembly. As with all Series KB–based keyboards, the switches are attached to mounting rails.

RW Series keyboards so far have been found to use 2SW Series keycaps (or a derivative thereof), with extra notches added to accept special wide keystem adapters.

Electronic Engineer magazine’s this is your keyboard reference from 1971—jointly a Micro Switch advertisement—depicts reed and solid state keyboards together, but does not name the series of either.


Keyboard Switches Date Notes
Potter Instrument KDR/KB 3100A Model 12 (51RW1-2) 7A1MT 7005
K50164-57RW ? 7014 Completely non-standard catalogue listing number
57RW1-2 chassis 7A1MS 7035
53RW4-1 chassis 7A1M-X14 7044


Part Description
RW-10038 8-to-4 binary encoder (DIP-16)
RW-10039 7-to-4 binary encoder (DIP-16)

RW-10038 and RW-10039 can be seen in the keyboard circuit diagram for the Mini Bee computer, as shown in the Mini Bee Computer Terminal Service Manual, with what appear to be fabricator part numbers WC 513 D and WC-514 D. Micro Switch 64SW1-4 has a similar if not identical circuit, and in this example, these two ICs were fabricated by Motorola and bear only Micro Switch’s part numbers. Both of these examples are SW Series Hall effect with two-of-N encoding, where these chips (two of each) provide the scancode conversion.


All documents were scanned by Bitsavers unless otherwise noted.