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.
- DN series
- Gold V-bar:
- Mercutronic, mercury-contact switches:
- MC series
- SS series
- M-5 series
- T-5 series
- Sabrecoil (switch array)
- T-15 series
- T16 series
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.
|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.