SK-8835, SK-8840 & SK-8845 pointing stick & UltraNav keyboards

The SK-8835/SK-884x family (models SK-8835, SK-8840, SK-8845, SK-8845RC and SK-8845CR) are a series of ThinkPad-style discrete keyboards produced by LITE-ON and marketed by IBM and Lenovo. Depending on the exact model and part number nomenclature, they are intended for space-saving desktop, travel, server/console, sysadmin, or storage appliance usage. First introduced in 2003, they were visually based on the then-current T30-era ThinkPads and their keyboards but sport unique keyboard assemblies not found on such ThinkPads. They also do not utilise strain gauge-based TrackPoint pointing sticks, instead, they use the force-sensitive capacitor^[1]-based Synaptics TouckStyk pointing sticks^[2]. All USB variants of these keyboards sport a two-port USB hub on the rear of the keyboard, but all variants allow for cable stowage and routing on the bottom and have two-setting flip-out feet. The family was originally introduced as an IBM one, however, Lenovo-branded ones first appeared in 2005 after they purchased IBM's Personal Computing Division (PCD)^[3]. IBM continued to have models manufactured with their name for use with IBM server consoles (until 2014, when Lenovo also purchased IBM's x86 Server Business^[4]) and for their storage appliances. Lenovo-branded ones have been spotted from as late as 2021^[5].

Contents

Summary

Pricing

All inflation adjustments were made with US Inflation Calculator.

Design

Key-switches

The SK-8835/884x family are typically laptop-like keyboards in that they use scissor-stabilised rubber dome over membrane key-switches (simply known as scissor-switches). Rubber dome actuators are dome-shaped rubber springs that collapse to provide travel and tactility. A keyboard membrane assembly is a form of circuit where traces (in this case, for the keyboard's matrix) are placed onto two thin sheets of plastic separated by some sort of spacer as a cheaper alternative to PCBs. These traces will have contact points that allow a key to be registered when these contacts on both membrane sheets are pushed together. Together, these two technologies form the most common type of keyboard key-switch^[9]. Scissor-switches are a specific type of low-travel rubber dome over membrane implementation where the small size of the actuator used requires additional stabilisation via two cross-arms that pivot on the keycap and the assembly underneath^[10]. It is not advised to attempt to take apart such keyboard designs as many of the components are compact and fragile.

SK-8835/884x family keyboards are produced by LITE-ON for IBM and Lenovo. During the era in which these keyboards were introduced, LITE-ON did not produce actual ThinkPad keyboard assemblies (which were instead usually sourced from ALPS and NMB). As such, the key-feel of these keyboards is often quoted as being "different" to actual ThinkPads^[11] and may require some adjustment time to get used to them. Opinions on them range, but they're generally described as 'middling'^[12]

Cover set & general design

SK-8835/884x family keyboards are based on the style of contemporary ThinkPads when its first members were introduced in 2003, which were the IBM ThinkPads T30, T40 and their R-series derivatives. The cues that indicate this are the grey coloured "F" and navigation keys and rounded "Access IBM" button (that's similar to a ThinkPad's ThinkVantage button) that both the preceding T20 and succeeding T60 lacked, and the roundness of the trackpad and its buttons that have not been seen on ThinkPads since the T40 series. As such, all SK-884x models resemble a T30 or T40 missing the screen. The SK-8835 extends the design with the addition of a dedicated numeric keypad that has not been seen on a discrete ThinkPad-style keyboard since and only started to appear on ThinkPad laptops when the W700 was released in 2008^[13]. Some ThinkPads before had complimentary numeric keypads released for them (such as the Ultrabay Plus Numeric Keypad), but these were optional extras.

The cover set design sports two pieces that are held together by a series of screws on the back and various plastic tabs around the edge, requiring careful prying to open.

All SK-8835/884x family keyboards have a dedicated space to allow the cable to be round and bundled flush inside the keyboard. The hold also has four possible exits for routing. Thanks to its larger size, the SK-8835's hold is about twice the width of the SK-884x's.

As indicated by the embossed text found inside the cover set, SK-8835/884x family keyboards are typically made with acrylonitrile butadiene styrene (ABS) plastic. However, four total resins are in fact embossed with an arrow pointing to the one used, so it's possible others were made with polystyrene (PS) instead. The resins include:

Unique to SK-8835

Unlike the SK-884x series, SK-8835 has an additional screwed-on panel that acts as a cable hold cover. Unlike its smaller siblings, SK-8835's numeric keypad membrane flex cable runs along this location, thus the keyboard assembly itself cannot be used as the cover. The SK-8835's top and bottom cover pieces have a [LITE-ON/Silitek] part number of 54-02811 and 54-02812 respectively.

Unique to SK-8840 & SK-8845 series

A noticeable cover set feature the SK-8835 lacks compared to its smaller counterparts is a cable gutter that surrounds the entirety of the flip-out feet, cable hold and rear label area underneath. This can be used to wound excess cable around.

Unique to SK-8845CR

The SK-8845CR's tooling differs slightly from its siblings. Apart from the obvious lack of trackpad support, the embossed text found inside used to indicate what material the cover set is made out of differs from that of its older siblings. Instead of four branded resins being listed, a generic ABS stamp is found and the three PS resins are replaced by a high-impact polystyrene (HIPS) stamp.

Internal assembly

SK-8835/884x family keyboards can have one (SK-884x) or two (SK-8835) subassemblies that house all of the key-switch components. These keyboard assemblies are designed like a typical laptop keyboard - they're essentially a tightly integrated sandwich of multiple layers including (from top to bottom):

Keycaps

The SK-8835/884x family keycaps appear to be ABS with pad-printed legends. ABS is the most common and generally affordable keycap material compared to its primary alternative, PBT. However, ABS keycaps are not as durable as PBT keycaps such as those found on all IBM Model F keyboards and most buckling spring IBM Model M keyboards. As a result, SK-8835/884x family keycaps can be prone to 'shining' after extensive use, which leaves the keycap surface smooth and will reflect more light. The text legends are also pad-printed, which can also be prone to wear. If you look closely at the keycaps, you may notice the outline of the label extended from the text and symbols themselves.

The keycaps' undersides are all of a similar design regardless of unit size - there's a structure in the middle used for pressing on the scissor-switches' rubber domes and two pairs of clips that attach to scissor mechanisms. However, the spacing of the clip pairs differs depending on unit size. There are also two known types of stabilisers on larger keys that are used to distribute applied pressure across the key to prevent binding (when pressing a key off-centre results in noticeable resistance or scratchiness feeling); one that slots into a pair of holes and one that is caught by a pair of clips, both near the scissor-switch mechanism.

Controller

There are two types of controller cards for the SK-8835/884x family - PS/2 and USB. The PS/2 controller card is of course unique to the SK-8840 and features an integrated controller chip that cannot be identified due to the resin blob placed on top. Most of the card is unpopulated and only matches the size of the denser USB controller cards to reach the same screw sockets and footprint.

The USB controller card is used by all other variants, although there have been several revisions throughout the almost two-decade production.

Original USB controller

The original USB controller card also sports a resin blob over an unidentified chip adjacent to the membrane flex cable connectors like the SK-8840 PS/2 controller card, however, there are two other prominent chips added. A Motorola XC68HC708KH12IFU and a Cypress CY7C63743-SC. The XC68HC708KH12IFU is a USB 1.1-compliant controller with an integrated four-port USB hub. It's a part of the Motorola 68HC08 family and its CPU is a descendant of the famous Motorola 6800 from 1974. The 68HC708KH12 specifically uses one-time programmable ROM compared to its 68HC08KH12 counterpart^[17]. The CY7C63743-SC is a part of the Cypress enCoRe [sic] brand low-speed (1.5mbps) USB and PS/2 controller family. It's an 8-Bit RISC microcontroller clocked at 12MHz and has 256 bytes of RAM, 8KB EPROM and 16 GPIO pins, with CY7C63743 specifically being the 24-pin version^[18]. SK-8835 and SK-8845 use the same overall controller card design, although the latter will simply lack the numeric keypad assembly membrane connector.

Circa 2007 revised USB controller

By 2007, the USB controller card had been revised with the Motorola XC68HC708KH12IFU being replaced by a Cypress CY7C66113C-PVXC and the CY7C63743-SC with a CY7C63743-SXC. The CY7C66113C-PVXC is a full-speed (12mbps) USB 2.0-compliant controller with an integrated four-port USB hub. It's an 8-Bit "USB optimised" microcontroller clocked at 12MHz and has 256 bytes of RAM, 8KB PROM, two 8mA GPIO ports and one 12mA GPIO port, with the "PVXC" variant being a 56-pin 300-mil SSOP package model^[19]. The CY7C63743-SXC is simply a lead-free version of the CY7C63743-SC^[18] it replaced for these controller cards. This controller card has generally been spotted on Lenovo-branded SK-8835s and SK-8845s.

Circa 2009 revised USB controller

When IBM introduced the SK-8845RC, they incorporated an updated Synaptics TouchStyk design (described in the following section) that mandated a change in flex cable design and they also simplified the board somewhat. The Cypress CY7C66113C-PVXC is still present, but the CY7C63743-SXC and the blobbed chip have been removed and instead a single LITE-ON "826-00140-03A" chip is now present, although it seems there are no publicly available specifications for it. It likely takes over both of the previous chips' functions. When the SK-8845CR was introduced, IBM reused the same controller design but simply left the TouchPad's flex cable connector absent.

Integrated pointing stick

All SK-8835/884x family keyboards use TouchStyk pointing sticks from Synaptics, Inc.^[2] The name "TouchStyk" is often associated with HP laptops that bear a pointing stick and IBM refrained from marketing this keyboard as using such in their marketing. They can be distinctly identified when the keyboard is dissembled by their gold-colour sensor assembly with three mounting points that house force-sensing capacitors^[1]. Since this pointing stick is also different from IBM's self-designed strain gauge based TrackPoint pointing stick, the name "TrackPoint" in marketing is also minimised. Instead, these keyboards are referred to as having an "UltraNav" (the combination of pointing stick and trackpad) or an "Integrated Pointing Device". Despite this difference to TrackPoint, TouchStyks on these keyboards have a stem adapter that allows them to use standard IBM/Lenovo nub caps. Two revisions of the TouchStyk pointing stick module have been observed on SK-8835/884x keyboards.

Original type

The original implementation (Synaptics P/N 920-000312-01) is the same design found on most contemporary IBM Model M-e PS/2 ANPOS and CANPOS Keyboards. It is a discrete module that is mounted onto the keyboard assembly's base plate. The sensor assembly is covered by a rubbery material and an adapter that allows standard IBM/Lenovo nub caps to be used. The module connects to the keyboard's controller card via a 10-pin flex cable - presumably, four pins are used for connecting to the keyboard controller card's IC and the other 6 are used for connecting the three mouse buttons dedicated for the TouchStyk. Due to the fact this module appears in both PS/2 and USB SK-8835/884x family keyboards (and the aforementioned PS/2 ANPOS and CANPOS keyboards), it appears this module is always a PS/2 device and that the controller card on the USB keyboards simply converts from PS/2 to USB for the host computer.

Revised type

SK-8845RC and SK-8845CR keyboards use a smaller version of the TouchStyk module (Synaptics P/N TS-01083-001) that uses a smaller 8-pin flex cable between itself and the controller board. Despite those changes, it appears to use a similar if not the same sensor assembly.

Integrated trackpad

All SK-8835/884x family keyboards except the SK-8845CR sport a Synaptics TouchPad integrated trackpad, which together with the TouchStyk pointing stick makes those keyboards "UltraNav". Whilst modern versions of the TouchPad support Windows Precision drivers and gestures, all SK-8835/884x family keyboards that have a TouchPad use older versions of the hardware that don't support such modern features.

Feet

All SK-8835/884x family keyboards have two-setting flip-out feet for height adjustment and rubberised stadium-shaped feet for grip.

Rear labels

More information: Keyboard Rear Labels topic

IBM and Lenovo continued the practice of providing strong documentation of the keyboard's type and date of manufacture in the form of a rear label sticker much like in spirit what IBM used with most Model F and Model M keyboards of the previous century. They are casually referred to as the keyboard's 'birth certificate'. The style used was consistent with those used for other keyboards made by LITE-ON/Silitek for IBM and Lenovo. Whilst the design remained very similar over the years and even between IBM and Lenovo branded examples, there have been some key points of variance:

Branding

Whilst the SK-8835/884x family is clearly designed to resemble a ThinkPad product, they more often than not are never branded as "ThinkPad" products or directly intended for the same markets. As such, the branding these keyboards have had has varied with only a brief period in the latter half of the 2000s where "ThinkPad" branded examples actually appeared. There have been 5 "eras" of branding (or lack of):

Connectivity

The PS/2 SK-8840 is a standard PS/2 device with a 3-metre Y-split cable. The keyboard can be connected to a modern PC lacking PS/2 ports via an active PS/2 to USB converter. The SK-8840 does not natively support USB HID scancodes, thus passive PS/2 to USB adapters are insufficient.

The USB SK-8835/8845 family keyboards connect to the host computer via a 1.5 or 3-metre cable with a single Type A USB plug. Architecturally, this USB cable leads into a four-port USB hub embedded on the controller card. Two of these ports are exposed to the user via two Type A sockets on the back of the keyboard, the other two are used for connecting the keyboard controller and pointing device controller (which exist as separate entities inside) together. As such, a USB SK-8835/8845 family keyboard will ordinarily enumerate itself as two (SK-8845RC/SK-8845CR) or three (SK-8835/SK-8845) devices to the operating system, which can be a combination of the following depending on the controller card revision a given keyboard has:

USB hub

When present, a two-port USB hub is potentially useful for USB flash storage or basic USB mice. However, note that there may be some limitations to its capabilities:

SK-8835

Known as the IBM USB Keyboard with UltraNav, Lenovo ThinkPad USB Keyboard with UltraNav or Lenovo ThinkPad Full-Size UltraNav USB Keyboard

The SK-8835 was the largest and likely the least common member of the SK-8835/884x ThinkPad-style keyboard family. Compared to its more common SK-8840 and SK-8845 series siblings, the SK-8835 has a dedicated numeric keypad and a larger cable hold underneath. It was available as a USB-only keyboard and thus had the two-port USB hub feature. Thanks to its ThinkPad-like main keyboard area, the SK-8835 is functionally a full-size keyboard in the width of a tenkeyless keyboard. It was announced as the IBM USB Keyboard with UltraNav under the OPTIONS by IBM brand in January 2003 with availability slated for March of that year. It was touted as the "ultimate accessory" for ThinkPad and NetVista users and its design similarity to ThinkPads used as its main selling point. The original SK-8835 series bore 31P89xx, 31P930x, 40Y779x and 02R04xx part and FRU number nomenclatures^[24][25]. After Lenovo's acquisition of IBM Personal Computing Division, the keyboard was repackaged as the Lenovo ThinkPad USB Keyboard with UltraNav as early as June 2007 with new P/N 41A51xx and 41N56xx nomenclatures^[26]. The Lenovo-branded keyboard was also known as the Lenovo ThinkPad Full-Size UltraNav USB Keyboard and was finally withdrawn from marketing effective 29th December 2009^[27].

SK-8845

Known as the IBM USB Travel Keyboard with UltraNav, IBM USB Travel Keyboard Option or Lenovo ThinkPad USB Travel Keyboard with UltraNav

The SK-8845 was the first USB tenkeyless member of the SK-8835/884x ThinkPad-style keyboard family. The SK-8845 was primarily intended for use with IBM desktop and ThinkPad laptops of the period^[28]. It was the first keyboard of the family to lack a dedicated numeric keypad, instead having an overlay numpad reminiscent of the IBM Model M Space Saving Keyboard (SSK). Like a typical "classic" ThinkPad keyboard, the layout manages to cram the functionality of a tenkeyless keyboard plus hotkeys into the width of a 60% keyboard. Being a USB model of the family, it has the characteristic two-port USB hub, although SK-8845 in particular is known for possibly having a shorter 1.5-metre cable or half of what its siblings have. It was announced on 28th January 2003 and released between 21st March to 2nd June 2003 for Europe, Middle East and Africa (EMEA)^[29] and 27th April 2004 for Asia and Oceania as the IBM USB Travel Keyboard with UltraNav under the OPTIONS by IBM brand with 02R04xx and 31Pxxxx part and FRU number nomenclatures^[30]. The SK-8845 has also been referred to as the IBM USB Travel Keyboard Option in an IBM IntelliStation M Pro context^[31]. The SK-8845 later became known as the Lenovo ThinkPad USB Travel Keyboard with UltraNav and was ultimately withdrawn from marketing effective 6th October 2009^[32].

SK-8840

Known as the IBM 1U Monitor Console Keyboard, IBM PS/2 Travel Keyboard, IBM PS/2 Travel Keyboard with UltraNav or IBM Keyboard with Integrated Pointing Device PS/2

The SK-8840 was the only PS/2 member of the SK-8835/884x ThinkPad-style keyboard family. It was intended for use in server console kits. Like its direct USB counterparts, it lacks a dedicated numeric keypad, instead having an overlay numpad reminiscent of the IBM Model M Space Saving Keyboard (SSK). Like a typical "classic" ThinkPad keyboard, the layout manages to cram the functionality of a tenkeyless keyboard plus hotkeys into the width of a 60% keyboard. Due to the keyboard being PS/2, SK-8840 is also the only member of the family not to have a two-port USB hub. It sports a 3-metre cable. SK-8840 was initially announced alongside the IBM 1U 17" Monitor Console Kit as the IBM 1U Monitor Console Keyboard and IBM PS/2 Travel Keyboard on 17th February 2004 with availability slated for 10th March of the same year. At launch, SK-8840 used 73P31xx and 89P85xx part and FRU number nomenclatures^[33]. By March 2006, this keyboard was also known as the IBM PS/2 Travel Keyboard with UltraNav^[8]. On 9th February 2006, a new P/N 42C00xx nomenclature was announced as the IBM Keyboard with Integrated Pointing Device PS/2 and slated for an 18th April 2006 release for IBM xSeries servers^[7]. P/N 42C00xx was later sold with IBM 1U 17-inch and 19-inch Flat Panel Console Kits but was withdrawn from marketing effective 31st October 2009^[34]. The original FRU 73P31xx series was available for IBM eServer Clusters as late as 31st December 2011^[35].

SK-8845RC

Known as the IBM UltraNav USB Keyboard or IBM Keyboard with Integrated Pointing Device USB

The SK-8845RC was a server-only variant of the SK-8845 and a part of the SK-8835/884x ThinkPad-style keyboard family. Like the other tenkeyless models of the family, it lacks a dedicated numeric keypad, instead having an overlay numpad reminiscent of the IBM Model M Space Saving Keyboard (SSK). Like a typical "classic" ThinkPad keyboard, the layout manages to cram the functionality of a tenkeyless keyboard plus hotkeys into the width of a 60% keyboard. Being a USB model of the family, it has a two-port USB hub on the pack. Compared to most SK-8845s that have 1.5-metre cables, the SK-8845RC has a 3-metre cable^[36] instead. Introduced as early as 2009^[37] under the original name IBM UltraNav USB Keyboard with 40K5xxx part and FRU number nomenclatures, they seem to be originally utilised with IBM 1U 17-inch and 19-inch Flat Panel Console Kits intended for use with rack-mounted IBM System x and BladeCenter servers^[38]. On 22nd July 2012, new RoHS 7cIII compliant versions of the SK-8845RC were made available as the IBM Keyboard with Integrated Pointing Device USB with a 94Y6xxx part number nomenclature^[39]. These were withdrawn as an option just over two years later on 31st October 2014 for IBM System x systems^[40].

SK-8845CR

Known as the IBM Keyboard with Integrated Pointing Device USB or Lenovo UltraNav Keyboard USB

The SK-8845CR is the youngest member of the SK-8835/884x ThinkPad-style keyboard family, based on the SK-8845RC design but lacking an integrated trackpad and thus technically the only 'non-UltraNav' member of the family. Like the other tenkeyless models of the family, it lacks a dedicated numeric keypad, instead having an overlay numpad reminiscent of the IBM Model M Space Saving Keyboard (SSK). Like a typical "classic" ThinkPad keyboard, the layout manages to cram the functionality of a tenkeyless keyboard plus hotkeys into the width of a 60% keyboard. Being a USB model of the family, it has a two-port USB hub on the pack. As a holdover from its SK-8845RC base, the SK-8845CR also retains its long 3-metre cable. The exact introduction date is presently unknown, but given this keyboard has been used with IBM/Lenovo 1U 18.5-inch Standard Media Consoles as the IBM Keyboard with Integrated Pointing Device USB with part and FRU number nomenclature 00MWxx and 46W67xx[%TIPS1048%], the introduction date could be as early as 25th September 2013^[42]. Interestingly, Lenovo later designates a single part number of this keyboard (00MW310) as the Lenovo UltraNav Keyboard USB despite specifically noting "This keyboard does not include a trackpad/touchpad" thus precluding it as an UltraNav design^[43]. By 2015, another part number (00WV000) was introduced for the IBM Storage Appliance 2421 Model AP1^[44]. Finally, by 2017, another IBM-branded example - P/N 01LK250 - has appeared^[22] but its origin is presently unknown. P/N 01LK250 is likely the last IBM-branded ThinkPad-derived/style product introduced. 00MWxx nomenclature SK-8845CRs were still being produced for Lenovo as late as 2021^[5].

Part number list

207 keyboard part numbers have been found in the ASK Keyboard Part Number Database. If you believe a relevant part number is missing, you can help improve this list by requesting a submission for it to be added.

Further reading & resources

Internal

External

Sources

ASK. Admiral Shark's Keyboards original content. License/note: CC BY-NC-SA 4.0.

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