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Stackpole were involved in some manner with Magsat Corporation in the production of magnetically-operated pulse-output switches and keyboards based around these switches. See the Magsat page for further details.


Lo-Pro is a series of miniature keyboard switches using coil spring–based switch contacts.


KS-200 is a switch array system, which is likely to be Stackpole’s standard pre-DIN switch grid system (see Stackpole switch grid on the Deskthority wiki). The typical lifetime per switch is given as 20 million cycles. KS-200 can be seen advertised in Computer Design in April 1981; see Documentation below. KS-200 keyboards could be ordered with or without keycaps, and with or without a PCB. KS-200 keyboards are described as non-encoded. The advertisement depicts a complete array (albeit too dark to make out), smaller arrays for function keys and number pads, and a single switch.

The arrays were intended provide keycap alignment (ensuring that keycaps are not crooked) and to remove the need for PCB stiffeners. (PCB stiffeners are rare, but Datanetics made use of them, and they can also be seen in some Apple II keyboards.) As there is no mounting plate to secure the switches, the arrays and single switches are affixed to the PCB with screws. Although it would be possible to form a keyboard from single switches, such an endeavour would be fairly pointless, and the discrete switches may be too large (without the shared walls) to fit into a ¾″ layout.

According to D’Milo Hallerberg from Hi-Tek, KS-200 was ultimately based directly on Hi-Tek High Profile, a move that led to failed legal action on Hi-Tek’s part. There is evidence to suggest that Stackpole’s original copy was closer in design to Hi-Tek’s, so KS-200 may represent the revised design with opposing pairs of identical contacts (one side solid, one side bifurcated) rather than Hi-Tek’s pairing of solid and quadfurcated contacts. The technical merits of Stackpole’s redesign require engineering understanding, but it did have the benefit of simplifying inventory and manufacturing by requiring only one contact part. This contact design would continue to be used in their later mechanical types.

Three patents are known for the high-profile array system. The first patent describes the type seen in an HP 2623A keyboard. This type uses one solid contact and one fingered (slotted) contact, just as with Hi-Tek High Profile. The characteristic stepped separator bar is also clearly depicted. The second patent shows the replacement dual bifurcated contact system, where both contacts within the switch are identical. A tactile type was also patented, which has yet to be encountered.

Patent Title Filed Granted Covers
US 4255635 Keyswitch 1979-09-17 1981-03-10 This appears to be the original array system, with separate solid and fingered contacts
US 4342892 Keyswitch 1980-08-08 1982-08-03 KS-200 array system with the matching dual bifurcated contacts
US 4361743 Lost motion keyswitch 1981-03-06 1982-11-30 Tactile version with hysteresis; uses the dual bifurcated contacts

Of the three patents, only the second one was transferred to Illinois Tool Works, in 1987.


Advertised in 1984, KS-200E is a DIN-compliant array system, replacing KS-200. The “E” in both this and KS-500E may stand for “ergonomic”, in relation to DIN compliance.

KS-200E uses a “sturdy monolithic housing that assures keycap alignment”, but it also offers “discrete switches or arrays”. The magazine advertisement depicts the a keyboard with PCB-mounted “interlocking” (“puzzle piece”) switches, which appears to be their discrete switch option. As these have been found in a Lear Siegler ADM 11 keyboard alongside switch grids, it would appear that the low-profile grids are the monolithic form of KS-200E.

Advertisements for KS-200E from 1984, scarcely viewable within Google Books, indicate that “tactile or linear feedback is available to your specs.”

There is some evidence to suggest that KS-200E was cloned; see the Eastern Bloc page for details.

The rated lifetime for KS-200E is 50 million cycles.


KS-500E is the companion membrane technology to KS-200E, advertised at the same time in Computer Design magazine. Like KS-200E, these are DIN-compliant. The rated lifetime was given as 10 million cycles in September 1983, and 20 million cycles in February 1984. Bounce time was given as under 1 ms when new, and 5 ms maximum at end of life. Travel is 0.140″ (3.6 mm).


KS-600E is a keyboard family using plate-mounted, discrete switches based on Stackpole’s existing switch design. KS-600E switches have 0.140″ (3.6 mm) travel, and like KS-200E are rated for 50 million cycles. These switches can be either linear or tactile, and Stackpole offered them for sale separately.

The switch is pictured in a magazine advertisement from August 1984. The excessive JPEG compression makes the switch design hard to discern, but it is not dissimilar to the linear switches used in the Zentec Zephyr DD/ID220 manufactured in August 1985, and this keyboard may well be from the KS-600E family.


All of the Computer Design material was scanned by Bitsavers unless otherwise noted.