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Lenovo ThinkPad USB Keyboard with TrackPoint (SK-8855)

Contents

Background

A Lenovo SK-8855<sup>1</sup>
A Lenovo SK-88551

The Lenovo ThinkPad USB Keyboard with TrackPoint (model SK-8855) was a ThinkPad-branded discrete keyboard produced by LITE-ON and marketed by Lenovo in the late 2000s and early 2010s. Released on 18th August 20092, the SK-8855 is visually based on the keyboard introduced several months earlier on the Lenovo ThinkPad T400s3 and used until the xx20 generation. It technically succeeds the [SK-8835/SK-884x ThinkPad-style keyboard family](wiki/page?id=ibm88xxultranav) introduced during the IBM days in the home and office markets, although new SK-8845 variants continued to be released independently by IBM's x86 Server Business during the same period the SK-8855 was on the market. The SK-8855 utilises a TrackPoint IV pointing stick but lacks a trackpad most of its predecessors had, precluding this keyboard from being an UltraNav keyboard. SK-8855 was withdrawn from the market by May 20144.

Design

The keyboard takes heavy design inspiration from contemporary ThinkPads, which included the T400s through T420 and their W-series (W510 and W520) and X-series (X220) counterparts. The telltale sign of this is the double-height Esc and Delete keys on the top row and the stylistic TrackPoint mouse buttons, which ThinkPads before the T400s lacked and ThinkPads after the T420 had the modern AccuType island-style keyboards. This type of design echos that of the SK-8835/SK-884x series, which too was easily associated with ThinkPads from its era such as the IBM ThinkPad T30. The overall design and feature set however is quite different between these two families. The SK-8855 measures 31.3cm x 22cm x 1.9cm (or 12" x 8.7" x 0.8"), with the 1.9cm height rising to 3.8cm (1.5") with the flip-out feet deployed. The keyboard cable is about 1.2 metres (3.95') long as the whole keyboard approximately weighs 0.46kg (1lbs)2.

SK-8855's rear side<sup>1</sup>
SK-8855's rear side1

The SK-8835/SK-884x series family was known for having flexible cable routing options, a two-port USB hub (excluding the PS/2-based SK-8840), a trackpad (excluding the SK-8845CR) and two-setting flip-out feet. The SK-8855 however lacks alternative cable routing options (although the cable stowage area is still intact), lacks a USB hub and trackpad, and only has single size flip-out feet. However, the SK-8855 now includes drainage channels to guide out liquids if some are spilt into the keyboard.

The internal technology is also different this time around. The SK-8835/SK-884x family used a unique (as in, not used on an actual ThinkPad laptop) keyboard assembly with Synaptics' TouchStyk force-sensitive capacitor based pointing stick implementation. SK-8855 uses a keyboard assembly very much like period ThinkPads and uses a true TrackPoint stick with strain gauge technology.

SK-8855's keyboard assembly<sup>1</sup>
SK-8855's keyboard assembly1

The keyboard assembly also seems to use the same internal matrix and TrackPoint connector as its contemporary ThinkPads. The one exposed PCB inside acts as the keyboard's controller and presumably a PS/2 to USB converter for the TrackPoint (as TrackPoint sticks are typically electronically PS/2 devices). Deskthority user davkol attempted to hook up a ThinkPad X200 keyboard assembly to the SK-8855 controller and found that the keyboard functioned although its Fn layer and left Windows key did not function1.

SK-8855's controller<sup>1</sup>
SK-8855's controller1

Further reading & resources

Sources

  1. davkol - Lenovo Thinkpad USB Keyboard with Trackpoint (aka SK-8855) [accessed 2021-10-16]. License: CC BY-SA 4.0 (cropped & perspective fixed).
  2. Lenovo - Lenovo ThinkPad USB Keyboard With TrackPoint - Overview [accessed 2021-10-16].
  3. ThinkWiki - ThinkPad History [accessed 2021-10-16].
  4. pkiff - Thinkpad USB Keyboard w TrackPoint gone? Replaced w chiclet? [accessed 2021-10-16].