Hi-Tek linear

From Deskthority wiki
Jump to: navigation, search
Template icon--Work in progress.svg This article is a work in progress — please treat material with extreme caution
Template icon--Illustration.png This article requires photographic illustration — page is relying too heavily on external references

This article is a stub. You can help Deskthority by expanding it.

Hi-Tek linear
Manufacturer Hi-Tek
Switch type Linear
Sense method Metal leaf
Switch mount PCB mount
Patents US3751618 (1972)

Hi-Tek linear is a provisional name for the predecessor of the Hi-Tek Series 725 switch. It is the switch basis for the Hi-Tek modular system, and based on patent dates thus far, long pre-dated the Stackpole switch grid. D'Milo Hallerberg has reported the name to be "Hi-Tek High Profile",[1] but whether this is a retronym applied after Hi-Tek Series 725 was introduced is not known, and no printed material has been found bearing this name.


Very little is known about the Hi-Tek linear switch. In many cases, Hi-Tek supplied only the switch grid, leaving the customer to supply the PCB and logic circuitry.[1] However, complete Hi-Tek "waffle frame" keyboards have been found (with a Hi-Tek branded PCB), confirming that keyboards in this form were indeed manufactured by Hi-Tek.[2]

Examination of Stackpole patents and confirmed Stackpole keyboards suggests the following characteristics:

Hi-Tek vs Stackpole.svg

The contact mechanism is formed of two leaf springs that are held apart by a horizontal bar in the slider; when the slider is depressed, the bar is lowered and the contacts close. The switches are open at the top.

The switch shares the same style of return spring (a tight cluster of turns in the centre as well as at each end), and the same contact mechanism, as the later Hi-Tek Series 725 switch.


For main modules with a flat surface, the Hi-Tek branding is placed above the space bar, just as with Hi-Tek modular keyboards. For modules with a "waffle frame" construction, it appears that there is no visible branding; it is theorised that white-infilled serial and product numbering around the sides of the mouldings is a Hi-Tek characteristic.[3]

Servicing and parts

Computer service manual findings show that, as the keyboard is monolithic, there were provisions made to service individual switches. Each switch component was assigned its own part number, and an insertion tool was available to assist with insertion of replacement contacts. Section 5.6.6 of the Lear Siegler ADM-3A maintenance manual contains an illustrated guide to replacing a pair of switch contacts using the insertion tool. This in itself appears to confirm that the ADM-3A keyboard was supplied by Hi-Tek (unless Stackpole used Hi-Tek part numbers).

The following part numbers have been found:

Part Part numbers
Plunger, momentary 173-40213 (NABU 3100)
Plunger, locking 173-40334 (NABU 3100)
Cam, locking 173-40260 (NABU 3100)
Spring, 2 oz none (NABU 3100)
Contact, solid 173-30107 (NABU 3100)
373-30052-2 (LSI ADM-3A)
Contact, fingered 173-30108 (NABU 3100)
373-30053-2 (LSI ADM-3A)
Tool for contact replacement 173-10023 (NABU 3100)
Stabiliser wire (8 units) 373-10020 (CDC IST II)
Stabiliser wire clip 373-30104 (CDC IST II)
Stabiliser insert 373-30105 (CDC IST II)

The NABU 3100 (formerly Volker-Craig VC3100) keyboard has yet to be seen, and it may be that some of these parts are specific to Hi-Tek modular.

The CDC IST II service manual also cites a 2 oz spring for normal keys, and a 3 oz spring for the space bar.


For keyboards built using the modular grid, see Hi-Tek modular.



In most instances, "waffle frame" keyboards are unbranded. Hi-Tek appear to have introduced branding around the time that the Hi-Tek modular switch was introduced. The following keyboards are being assumed to be Hi-Tek for now:

  • DEC DECWriter LA36(?) keyboard, manufactured by Cherry US (black sliders)[10]
  • DEC GIGI terminal keyboard (black sliders)[11]
  • DEC VT100 terminal keyboard, with normal sliders[12] and unusual sliders[13] — the former is confirmed to have a Hi-Tek lock switch
  • HP 2382A terminal keyboard (white sliders, and white serial numbers)[3]
  • IMSAI IKB-1 Intelligent Keyboard (black sliders)[14]


Flat-top switches

See also


  1. 1.0 1.1 Telephone conversation with D'Milo Hallerberg, 2015-08-03
  2. Deskthority — Hi-Tek keyboard
  3. 3.0 3.1 Deskthority — HP2382A terminal keyboard
  4. (Wayback Machine) AtariAge Forums — 600/800XL Keyboard variants Archived 2005-06-01.
  5. AtariAge Forums — Hacking the Atari 800 Keyboard & CX85 Keypad onto a USB PC Keyboard Circuit Dated 2009-12-26. Retrievd 2015-07-27.
  6. AtariAge Forms — 800 Restoration Dated 2012-11-24. Retrieved 2015-07-27.
  7. The Dragon Archive — Pippin Last updated 2014-12-06. Retrieved 2015-07-27.
  8. Vintagecomputer.net — Vintage Computer Photos subject: LSI ADM3A Retrieved 2015-07-27.
  9. Deskthority — Volker Craig vc4152
  10. Geekhack — A visit to my local electronics shop Posted 2013-07-05. Retrieved 2015-07-27.
  11. The Vintage Computer Forums — keycaps: NOSCROLL and SETUP keys for DEC VT100 style keyboard Dated 2010-05-22. Retrieved 2015-07-27.
  12. Deskthority — DEC vt100 'cyber' keyboard
  13. Geekhack — Keyswitch ID thread Posted 2013-08-06. Retrieved 2015-07-27.
  14. Geekhack — keyboard switches used in IMSAI IKB-1 from "Wargames" (1983) film Posted 2013-12-17. Retrieved 2015-07-27.