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Mechanical Enterprises

United States



Mechanical Enterprises, Inc. was founded by the late Robert Hull Twyford (born 1932 or 1933, died 2013), a former rocket engineer from Tennessee who served under Werner Von Braun. The company appears to have been founded in 1960, to market an invention he co-patented with Stephen E Hartnett (US patent 3063541, filed on the 7th of October 1960), a system for permitting typewriters to type an unlimited number of additional symbols. This system was called “Typit”, and it operated by interposing a striker assembly between the paper and typebars.

Advertisements from the early 1960s show that Mechanical Enterprises did not yet have (or did not choose to use) a logo (e.g. Analytical Chemistry, February 1962), while Typit was advertised in all uppercase. In 1966, advertisements for Typit (e.g. Analytical Chemistry, February 1966, and the Journal of Symbolic Logic) used an all-lowercase “typit” logo in a typewriter typeface. By 1971, the single “M” logo appears in advertisements for Typit, and Typit appears to have stopped being advertised with a logo of its own (e.g. Mathematics of Computation, April 1971).

Mechanical Enterprises’ CAGE code was 29090.


In 1990, Mechanical Enterprises reincorporated as Datalux after Bob Twyford bought out his old partners, and the business was relocated to Winchester, VA. The Datalux advertisement in Electronic Engineers Master catalogue for 1991–92 states Mechanical Enterprises Incorporated became Datalux Corporation on the 15th of June 1990. Datalux continues in business to this day. The Company Overview page on the Datalux website notes that the “company’s first product was the SpaceSaver keyboard”, and dates the company to 1990, making no mention of Mechanical Enterprises, or that both the SpaceSaver keyboard and its switches pre-date Datalux, with the Microtype Space-Saver Keyboard having been introduced around 1988.



Details on MEI switches is scarce. Most types discovered to date are covered by a patent, with T-5 being an exception. It appears that M-5 was also not covered directly by a patent, and it shares its general design with T-5.

Mechanical Enterprises took the unusual decision to produce mercury-contact keyboard switches. The original Mercutronic keyboard switches were also one of the self-encoding switch designs.


In their 1988 and 1989 Electronic Engineers Master Catalog advertisements, MEI offered stock 16, 20 and 64-position keypads and keyboards based around T-15 switches. These were matrix-only assemblies.



Patent Title Filed Published Product
US 3063541 A Character adding device for typewriting equipment 1960-10-07 1962-11-13 Typit
GB 938020 A Character adding device for typewriting equipment 1961-04-05 1963-09-25 Typit
US 3537565 A Adapter for positioning a character adding device on typewriting equipment 1967-10-31 1970-11-03 Typit
US 3547247 A Character adding device for typewriting equipment 1968-02-23 1970-12-15 Typit
US 3582594 A Actuator useable for electric switches and the like 1968-11-15 1971-06-01 Undiscovered switch type
US 3600537 A Switch 1969-04-15 1971-08-17 Mercutronic miniature snap-action switch (“microswitch”)
US 3707611 A Coding keyboard and electrical switch therefor 1970-09-29 1972-12-26 Mercutronic switches, including MC series
US 3845264 A Switch with liquid containing tube for keyboard use 1973-04-09 1974-10-29 Mercutronic SS series
US 4004121 A Electrical switch with wire beam spring contact closer 1974-04-04 1977-01-18 Appears to be the patent for gold V-bar switches (LFW and LM)
US 4203016 A Electric switch utilizing coil spring torsion biasing in switch operation 1978-11-08 1980-05-13 Sabrecoil
US 4433317 A Controlled floating contactor switch 1982-12-16 1984-02-21 DN series
EP 0084331 A1 Controlled floating contactor switch 1983-01-07 1985-08-14 DN series
US 4600819 A Switch assembly 1985-03-08 1986-07-15 T-15 series
US D319631 S Miniature keyboard 1988-03-18 1991-09-03 Design patent for the Micro-type keyboard, later rebranded Datalux Spacesaver


All documents were scanned by Bitsavers unless otherwise noted.