Controls Research Corp
Controls Research Corporation (CRC) is a very poorly-understood company. Examples of their keyboards and switches are rare almost to the point of nonexistent. One keyboard example has been found, as has one calculator example. Additionally, a bare keypad has been found.
The CRC Mark II keyboard was a bespoke keyboard arrangement built around CRC 02 discrete snap-action dry reed switches.
The Mark II keyboards brochure indicates that there are patents pending, but no US patents for Controls Research Corporation seem to have been digitised. Sadly the brochure gives no indication of its age.
CRC 02 is a tall discrete reed switch module offered with CRC’s Mark II keyboards. These switches were advertised as having “magnetic snap action”. The design is fairly tall, measuring 2.025 inches from the centre of the switch base to the top of the keycap. The top of the switch body is 1.25 inches from the PCB, measured from the centre of the base. The base of the switch is angled to 10° to provide a stepped profile when the PCB itself is angled likewise. Switches are secured to the PCB using a pair of 2-56 machine screws.
The switch is illustrated in the brochure as follows:
The switch specifications are as follows:
|Travel||0.156″ (around 3.96 mm)|
|Return force||1 oz (around 28 g)|
|Snap force||3 oz (85 g)|
|Contact life||1 million cycles|
|Bounce time||0.5 ms|
|Voltage||40 V maximum|
|Current||50 mA maximum|
The switch diagram has the keycap labelled “I.B.M. KEYTOP”, which is shown as truncated in the top view, and cuboid in the side view. The keycap mount is not illustrated, but chances are it will be flat stem mounting.
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. Reed switch modules matching the style of the Bi-Pac modules can be seen in an unidentified CRC keypad, with PCB part number 13C0117200-4. The plunger guide shafts of these modules seem to be considerably taller than those of Bi-Pac. The production date is not clearly marked, but the PCB is stamped “34 73” which may be the week and year.