Controls Research Corp
Controls Research Corp is a very poorly-understood company. Examples of their keyboards and switches are rare almost to the point of nonexistent.
Bi-Pac is a mechanical switch type whose switch contacts are a pair of concentric coil springs. The wider outer spring has the top end formed into a horizontal bar, and as it is pressed down by the plunger, it makes contact with the top of the inner spring. The springs form the solder terminals. Overtravel is achieved when the inner spring is also compressed.
The switches are formed into blocks that are almost identical in layout to Key Tronic and Maxi-Switch switches. The switch blocks and inner workings are illustrated in Electronic Design magazine in 1972 [ED1972-FOK], under the name “Bi-Pac”.
British patent 1345831 filed in May 1972 covers the switch. Priority was given to a US patent application, but this patent cannot be found.
There is only one confirmed example:
- Micro Computer Machines MCM/70 keyboard, assembled in Mexico in 1974, and labelled “N10046 REV AP1” and “B30041-1 REV AP1”.
In [ED1972-FOK] a complete calculator keypad is shown, that uses Bi-Pac switches. A very similar CRC keypad was used in the Summit 3114, with the main difference being a slightly different key arrangement.
In [ED1972-FOK], it was mentioned that CRC also offered reed switches. No details on these were given.