Jump to page content

C. P. Clare & Company



C. P. Clare & Company, Pendar, Clare-Pendar, Clare, General Instrument and the separate Pendar Électronique in France have together a complex and still poorly-understood history. See history for the most recent reconstruction of this history. For products specific to General Instrument (in particular semiconductors) see the separate General Instrument section. This section only covers product ranges under official Clare or General Instrument ownership; see the Pendar section for the unrelated activities of the separate Pendar Électronique that followed a buyout of European production from General Instrument.

Keyboards history

Following C. P. Clare’s acquisition of Pendar in 1966, keyboards and keyswitches were produced under the Clare-Pendar name; this can be seen in magazine advertisements from 1970–1976. Keyboard advertisements in 1978 (of which there were numerous) used the C. P. Clare name instead, and in the 1980s the keyboards were sold as General Instrument products.

Clare-Pendar were one of the companies to adopt matrix scanning around 1970: a Clare-Pendar advertisement in Electronics magazine in November 1970 describes their LSI/MOS–encoded matrix scan keyboards. These keyboards were scanned at 50 kHz, taking 20 microseconds to scan each key. The encoder supported either three modes or four levels (the article claims both) and 9-bit output codes for up to 88 keys in 2000 bits of ROM; something seems wrong, as 88-key 9-bit tri-mode would require 2376 bits of ROM, and quad-mode would require 3168 bits. The scanning process was advertised as having much less power consumption than Hall effect, at 200 mW vs 5 W for Hall effect. The price per keyboard was listed as $250 in small quantities, with production quantities expected to bring the price below $100 per unit. These keyboards used reed switches.

Initially a reed keyboard manufacturer, Clare-Pendar also turned their attention to mechanical switch keyboards. No literature is known for their Series S840 keyboard switches, but keyboards using them (such as the Bendix keyboard made for NASA, and some Texas Instruments Silent 700 keyboards) can be found as far back as 1973.

Under the C. P. Clare and General Instrument names, they also produced foam pad capacitive keyboards.

In 1978, they advertised microprocessor-based “intelligent” keyboards, in both reed and capacitive forms.



The North American and European products had some crossover in the form of the low-profile reed switches, but were otherwise separate. US-made switches were sometimes branded C.P. Clare, Clare-Pendar or GI, but S840 series in particular seems to have always been marked only as “ASM MEXICO” indicating assembly in Mexico.

Series Branding Type
S700 “ASM MEXICO” Low-profile foam and foil with hysteresis; the sliders are marked “ASM MEXICO” while the PCB bears the series name and “General Instrument Computer Products Division”
S820 Clare-Pendar Reed (tall); a later design has been found marked both “CLARE-PENDAR” and “ASM MEXICO”
S830 Clare-Pendar, G.I. Reed (tall)
S840 “ASM MEXICO” Metal contact
S870 Unknown “gold crossbar”
S880 None; “ASM MEXICO” Reed (short)
S890 CP Clare, “ASM MEXICO” Foam and foil
S950 General Instrument These are a derivative of Alps KCC/SKCC Series, and may have been manufactured by Alps Electric on behalf of General Instrument (otherwise, Alps must have sold the plans to the tooling).
SF/SG/SH/SI/SK Clare Reed (high-profile)
SFL/SGL/SIL Clare Reed (low-profile)

The modifications chart also mentions S860 series but Electro-Mech have no documentation on this.



Patents relevant to Clare/Pendar computer keyboards and switches.

Company Patent Title Filed Published Notes
Clare Pendar Co US 3771636 A Space bar assembly 1971-04-02 1973-11-13 This is the characteristic Clare-Pendar space bar assembly with the interlocking bars
General Instrument Corporation EP 0072784 A2 Keyswitch design 1982-08-10 1983-02-23 A design for a single-sided foam and foil PCB where the capacitor pads are through-hole soldered!
General Instrument Corporation US 4450332 A Keyswitch design 1982-08-25 1984-05-22 This appears to be for the foam and foil switch series mentioned earlier
General Instrument Corporation US 4454562 A Keyswitch with telescoping plunger 1982-09-15 1984-06-12
General Instrument Corporation US 4453198 A Linear feel keyswitch with hysteresis 1982-09-15 1984-06-05 That is a strange definition of “linear”
General Instrument Corporation US 4433225 A Keytop levelling mechanism 1983-02-22 1984-02-21 This may be the origin of scissor switches


Some North American–made products have “97564” moulded into them or stamped on them, which at least one supplier has since mistaken for a manufacturer part number. This is in fact the CAGE (Commercial and Government Entity) code. Depending where you look, this number has been applied to: