IBM Japan 5576-C01 TrackPoint Keyboard and its Unicomp descendants

The IBM Japanese Keyboard/TrackPoint II (model 5576-C01) is undoubtedly one of the coolest keyboards IBM fielded in the 1990s. It's a buckling spring Model M with a TrackPoint pointing stick sporting a JIS layout and many unique design elements. It's very likely the rarest IBM TrackPoint keyboard. However, detailed analysis of this keyboard is hard to come by in the west and there's an interesting story to tell with how the design ended up becoming the Unicomp EnduraPro, Ultra Classic and SpaceSaver M that are still available today. Thus, this article will explore the 5576-C01 inside and out, highlighting changes to its closer western counterpart - the Model M13 - and showing how Unicomp took the design and tooling and made it their own.

Contents

Introduction

The 5576-C01 is a keyboard potentially loved by many. It's an IBM keyboard, a keyboard with buckling springs, a keyboard with a TrackPoint pointing stick, a keyboard with a JIS layout and is a Japanese exclusive product. Many possible stakeholders indeed. The Unicomp EnduraPro and Ultra Classic are current market keyboards. Thus naturally you'd think all these, their history and their relations would be well documented, right? Unfortunately for the western side of the hobby, not as much as I'd like. The keyboards are known and the 5576-C01 in particular indeed has a fanbase, but the fact that the 5576-C01 and the Unicomp EnduraPro and Ultra Classic are related has escaped even respected vintage keyboard enthusiasts is something I want to address. As I like to stress; to no one's particular fault, but it's something I can help with!

The 5576-C01 is a keyboard for the IBM PS/55E (type 5538), a Japanese-exclusive all-in-one PC first released in October 1993. The IBM Personal System/55 (PS/55) line itself was a Japanese-exclusive line of IBM PCs first released in 1987 with its most notable members architecturally based on the Micro Channel (MCA) bus IBM Personal System/2 computers from the Americas, Europe, Middle East and Africa used, making PS/55 essentially the Japanese equivalent of IBM PS/2. However, compared to PS/2, PS/55 had region-specific features such as a display adapter with an onboard Japanese font that allows the host systems to display Japanese text without loading the font to RAM^[1][1]
Wikipedia - IBM PS/55 [accessed 2022-08-11]..

Now regarding the PS/55E, it was in fact very different from other PS/55 machines; they're not MCA (or 5550) based for starters, but as aforementioned, they're also an all-in-one system. They were known as the IBM Green PC, highlighting the intent of the system - to meet the Energy Star defined "Green PC" specification promoted by the likes of the US Environment Protection Agency and Department of Energy during this time. This makes the IBM PS/2E (type 9533) its closest western counterpart. Whilst both systems were considered to be too expensive and came to market too early, they were a glimpse into how compact PCs could end up becoming. The PS/2E achieved this by maintaining a degree of component commonality with period IBM ThinkPad laptops^[3][3]
Computer Museum - Humboldt University of Berlin - IBM PS/2E [accessed 2022-08-11]., PS/55E may have also done something similar. Specifically, the use of LCDs in both models would have suppressed some power consumption. The PS/55E later adopted the name "PC Stream", which with the preceding "Green PC" name makes up two small generations of the system.

There are ten variants of PS/55E known, with four of them - models 5538-YWC, 5538-YAC, 5538-ZWC and 5538-ZAC - known to include an IBM 5576-C01 as standard. The other Green PC era systems had options for their keyboards, which I presume included keyboards such as the Brother-made IBM 5576-A01 and Mitsumi-made IBM 5576-B01. It's unclear what keyboards the "PC Stream" models shipped with, but it may have also had multiple options. There's also an additional type 5537 of PS/55E which is a "PC Stream" without any display^[4][4]
Ardent Tool - Model 5538 PS/55E [accessed 2022-08-11]..

The OG 5576-C01

The 106-key 5576-C01 takes home several accolades for the Model M family and even IBM keyboards at large; it is likely the rarest IBM TrackPoint keyboard, it was one of the last unique Model M designs introduced during the IBM-Lexmark era, and it's the most compact full-size buckling spring Model M with a curved metal backplate. It is also the only IBM keyboard with the large rotating foot that we'll get to in a second...

The most notable styling element of the keyboard is the notch on the rear-upper lip, which can also be found on the also Japan-exclusive IBM 5535-ZPP Numeric Keypad (P/N 69H8533) that I 'figured out' in an article last year. This is the easiest way to identify a 5576-C01 from the other 5576-series keyboards (other than the TrackPoint, of course) or its western Model M13 sibling. The purpose of it is unclear since without any flip-out feet deployed it lacks a significant angle that might make it useful and secure enough to hold pens and pencils on it. In terms of branding, a white-on-grey IBM oval logo can be found on the LED lock-light overlay sticker that in a way is perhaps an early clue into how Unicomp would end up branding most of their keyboards.

5576-C01s could come with two types of cable based on their part number - 66G8362 with separate PS/2 plugs for the mouse and keyboard connections (like my example) and 66G8363 with a single combination plug. Due to this, P/N 66G8363 will not be fully operational if connected to a standard PS/2 port or PS/2 converter but it has been said to work when connected to IBM portables such as the ThinkPad 235^[5][5]
Tsuyoshi Ide @ ide-research.net - 5576-C01 [accessed 2022-10-11]. License/note: used under permission.. If the ThinkPad 235's PS/2 port is the same as typical ThinkPad onboard PS/2 ports of the era that allowed for an optional keypad and mouse to be connected together, P/N 66G8363 may be wired in such a way where the standard PS/2 plug pin positions are used for mouse connectivity and the two usually unused pins are used for keyboard signalling. IBM keypads such as the Model M3 PS/2 L40SX Numeric Keypad, KeyPad III and aforementioned 5535-ZPP Numeric Keypad are wired in this fashion.

Moving on to the 5576-C01's party piece, we have the huge rotating foot on its back wall. The purpose of it? Once again, it's unclear. I hypothesise that it's designed to allow the keyboard to be parked on its back wall, allowing the user to increase usable desk space (for writing, etc.) as needed. I think that makes sense for a PC with some space-saving intention in its design and for an era where handwriting was more common than it is now. In a conversation with him, wendell @ Level1Techs believes it may have been intended to prevent the keyboard from slipping off something like a "lapdesk"^[6][6]
Level1Techs Forums - Mechanical Keyboard Corner [accessed 2022-08-11].. It's very possible both are right or both are wrong.

If you're wondering what the case is made out of, it's a polycarbonate and acrylonitrile butadiene styrene (PC + ABS) copolymer, the same stuff used for the casing of the IBM Models M3, M4/M4-1, M7, M8, M9 and M11 - basically everything that isn't an Enhanced Keyboard derived Model M. The resin used was General Electric's CYCOLOY C2950, which is still commercially available via Sabic (who bought General Electric's plastic business in 2007^[7][7]
General Electric - GE Announces Sale of Plastics Business to Sabic for $11.6 Billion; Industrial Portfolio Transformed for Stronger Growth; Proceeds to Be Used for Stock Buyback [accessed 2022-09-18].) and is a part of their FR (fire retardant) series as the "standard high heat grade" option intended for "appliances, lighting and electrical" applications^[8][8]
Sabic - CYCOLOY™ FR Resins [accessed 2022-09-18]..

In terms of general keyboard design (ie, assembly, switches and keycaps), the 5576-C01 is clearly a Model M. They use IBM's famous buckling spring over membrane clicky key-switches made in the west, interestingly contrasting IBM Japan's other 5576 series buckling spring keyboards made by Brother that used their own take on the key-switch design. 5576-C01 was instead made by (or for) IBM in the United States. The reason for this was likely the convenience of shared components - the concept of a clicky keyboard with a TrackPoint pointing stick was already implemented, the Model M13. The Model M13 is probably the most famous keyboard with a pointing stick and was already in production in the Americas at this time, so IBM may have subcontracted production of the 5576-C01 keyboard assembly to Lexmark to simplify manufacturing and maintain component and tooling commonality where possible. The keycaps are then of course the Model M's famed uni-profile dye-sublimated PBT variety, featuring durable printing and durable material. Besides the JIS layout and the font size differences, the keycaps are as you would expect from a Model M save for the convexed modifier keys and non-stepped 1.75-unit right shift key.

In regards to the TrackPoint stick itself, it's the same strain gauge based TrackPoint II stick IBM was also employing on the Models M4-1 buckling sleeve keyboard, M6/M6-1 early ThinkPad buckling sleeve keyboard, and IBM-brand aforementioned M13 buckling spring keyboard. As for the mouse buttons, they also use similar not-very-clicky blister-style switches as those other keyboards and is probably the weakest aspect of IBM's keyboard pointing devices of the period. If you open up this keyboard, you will find a clearly Model M-type keyboard assembly featuring a curved backplate and melted plastic rivets.

The backplate is not quite the same as an M13's as it has a top corner cut down and edges trimmed, but the controller card is very similar to a period (ie, Lexmark or Maxi Switch made) IBM Model M13 controller, reinforcing my belief that production was based in the Americas to take advantage of the resources M13 production had created. The only major difference worth mentioning is that the 5576-C01 controller card has five large ferrite cores the M13 controller card lacks. Maybe at some point both 5576-C01 and M13 shared the exact same controller cards because they're so similar, but this requires further research as all the M13s I have on hand are newer than my 5576-C01.

Unlike your typical Model M, there's no elaborate 'birth certificate' on the outside to indicate when the keyboard was made. However, there are some dates to be found inside, on the backplate. My example actually has three dates; one engraved into the backplate itself and two printed on labels. All three dates are different, with the latest indication being 9th September 1994. I'm not sure why there are two labels of the same style with different dates nor why one has a green and yellow mark on it. Anyway, the printed labels also reveal the inner assembly part number of 1403247.

Like most M13s, 5576-C01s sport a passthrough port for PS/2 mouse connectivity. This is achieved via a daughterboard present in the top-right corner of the keyboard that simply passes the PS/2 connection to the controller card, which itself also just passes through the keyboard cable. The daughterboard also has three capacitors that I believe serve as decoupling capacitors, presumably for protecting the keyboard controller and cleaning signals. Whilst the M13's version of the daughterboard has all the same components, it's less compact.

Whereas pretty much all Model Ms with fixed cables before 5576-C01 used a separate plastic piece for retaining the cable by clamping down through two rubber pieces fixed to the cable itself, 5576-C01 employs a 'slalom' (for lack of a better word) retention/stress relief instead. It's an approach that technically works but seems to leave the cable permanently disfigured, though in practice this should be fine so long as you place the cable the same way you found it if you ever open one of these and remove its cable. As a final observation, the 5576-C01 uses a slightly stubbier LED lock-light daughterboard compared to most of its contemporary and older Model Ms but features the same LEDs and Triomate connector.

Modernising into EnduraPro

How Model M production changed hands in the '90s is well told at this point. You know the story - Lexmark pulled out of keyboard manufacturing by April 1996 due to keyboards becoming less relevant to their business, which was likely due to competition from cheaper keyboard designs and the fact IBM was pursuing such cheaper designs from the likes of Chicony, NMB and Silitek. Some former Lexmark (in some cases, both ex-Lexmark and ex-IBM) employees started Unicomp to continue producing Model M keyboards in Lexington under their own brand, for other companies such as Affirmative Computer Products, General Electric Healthcare and even IBM. It's understood that Unicomp's acquisition of former IBM and Lexmark tooling wasn't a clean transition^[10][10]
/u/funkmon - I typed on the new Unicomp SSK. *Write-up of visit to Unicomp* [accessed 2022-09-18]. and it's not clear how or when the 5576-C01 tooling ended up in their hands. But on 1st November 1999, Unicomp made its first press release regarding the 5576-C01's successor - the EnduraPro. It can be found through the Wayback Machine (which I used to dig up a lot of the following information) and is boldly titled "The good old keyboard is now ready for the new millennium". It seems EnduraPro was going to be a family of keyboards rather than a single release, with the mentioned EP/104 being the only release to make it to market. It mentions:

As far as I could tell, these other 'EnduraPros' never made it to market, with Unicomp instead adding USB support to most of its existing keyboards a few years later. The press release also mentions a demonstration at COMDEX Fall '99 and the EP/104 was slated for a December 1999 release but the launch was delayed. As of 10th May 2000, the EP/104 product page stated shipments of the keyboard would start August 2000^[11][11]
Unicomp - EnduraPro104 [accessed 2022-09-18]. License/note: retrieved via Wayback Machine (2000-05-10 capture).. That notice was dropped by 10th November 2000^[12][12]
Unicomp - EnduraPro104 [accessed 2022-09-18]. License/note: retrieved via Wayback Machine (2000-11-10 capture).. To coincide with its launch, Unicomp also prepared a page bullet pointing a few ideas on the uses of the EnduraPro's programmable features as well as asking for more suggestions^[13][13]
Unicomp - Ideas for the EnduraPro 104 [accessed 2022-09-18]. License/note: retrieved via Wayback Machine (2000-09-19 capture).. By 8th June 2003, Unicomp updated the EnduraPro/104 page to mention that a raven black version of the keyboard was now available^[14][14]
Unicomp - EnduraPro104 [accessed 2022-09-18]. License/note: retrieved via Wayback Machine (2003-06-08 capture)., which as shown above, originally included white text on black background (WoB) keycaps much like the older IBM-branded raven black Model M13s. By 8th October 2003, the EnduraPro/104 page had been further revised compared to the earlier 3rd August 2003 snapshot^[15][15]
Unicomp - EnduraPro104 [accessed 2022-09-18]. License/note: retrieved via Wayback Machine (2003-08-03 capture).^[16][16]
Unicomp - EnduraPro104 [accessed 2022-09-18]. License/note: retrieved via Wayback Machine (2003-10-08 capture).:

By 11th October 2004, the entirely raven black EnduraPro was no longer mentioned, instead a "two-tone Black with metallic buttons" keyboard is mentioned and pictured in its place^[17][17]
Unicomp - EnduraPro 104 [accessed 2022-09-18]. License/note: retrieved via Wayback Machine (2004-10-11 capture).. This is essentially the same style of EnduraPro they're known for today, except the "metallic" feature on the keycaps was eventually dropped. Unicomp's metallic grey keycaps from this period are known for degrading into a greenish hue, thus they got replaced with their current "bluish" grey keycaps that don't suffer from the same issue. By 29th October 2005, the USB version of the EnduraPro was made available^[18][18]
Unicomp - EnduraPro 104 [accessed 2022-09-18]. License/note: retrieved via Wayback Machine (2005-10-29 capture)..

Anyway, enough trawling through the depths of the Wayback Machine for now. Let's get into the EnduraPro and see how it differed from the 5576-C01...

My example is a 2019-made P/N UB43PJA, the standard raven black USB EnduraPro with a 105-key UK ISO layout that you can still buy today. About 25 years between this keyboard and the 5576-C01. The overall shape of the keyboard remains the same, with the most noticeable change being the fact the piece of plastic that once separated the Ctrl and Alt keys on the 5576-C01 has been deleted to make way for GUI keys.

Unicomp doesn't (and seems to have never) offer 101/102-key layouts with classic Model M bottom rows for EnduraPros, but they have employed four styles of GUI key-equipped bottom row placements:

Unicomp has made its mark quite literally in other ways as well. Like all other Unicomp keyboards, "Model M", "+5V", a symbol for direct current and "Unicomp" are embossed directly onto the bottom case piece. Usually around where the 'birth certificate' label resides. Another big giveaway is the loss of the large rotating foot, which has been replaced with a textured mould filling for the top case piece and an untextured one for the bottom piece.

In other ways though, much remains the same on the outside such as the characteristic notch on the rear-upper lip, the style of the standard flip-out feet, the cable router and the screws.

EnduraPros seemed to have retained the same outer case materials make-up as the 5576-C01 as well. The embossed information on the insides of the casing reveals they too use General Electric's CYCOLOY C2950 PC+ABS copolymer. The keyboard assembly's barrel plate is made of just polycarbonate as per the embossed text that can be found once you remove some keycaps.

On the inside, the is a mix of positive and neutral changes and a particular negative change to consider. The negative one is the move from a strain gauge based TrackPoint pointing stick to a force-sensing resistor (FSR) pointing stick that Lexmark used to use for self-branded and non-IBM OEM pointing stick keyboards back in the day. Whilst it technically works as a pointing stick, you may be disappointed if you're used to any IBM or Lenovo TrackPoint. This is a topic I explored before in my M13: Lexmark versus Unicomp article from July 2020, but what you need to know is that whilst TrackPoint is always stationary, the Lexmark-Unicomp FSR stick moves like a small joystick. A joystick whose maximum potential is blocked by the adjacent keycaps, especially in the left, up-right and down directions. However, on a positive note, the mouse buttons Unicomp now uses are clickier.

In line with other buckling spring Model M keyboards, the controller card was also changed to a pressure-fit style card initially introduced in 1995 with IBM's P/N 42H1292 Enhanced Keyboard and its EMEA and South American counterparts. Such controller cards can be dubbed as "overnumpad-style" by the community today due to their location on the keyboard assembly. Instead of socketing the membrane flex cables via Triomate connectors, the membranes' contacts are now held to the controller card's contacts at pressure. The change in controller reduced the part count and power consumption significantly^[22][22]
Scott W. Vincent - Power Consumption of IBM Model M Keyboards [accessed 2022-02-01].. IBM and Lexmark back in the mid-'90s didn't port this controller to other Model Ms including the 5576-C01, so Unicomp did it themselves. One notable visual consequence however is that LEDs are placed differently compared to the old 5576-C01 daughterboard's placement due to the position of the membrane connection pins and the large integrated controller [that the PS/2 version of the controller has], which is what gives fourth-generation Model Ms their characteristic appearance of having lights that are aligned in the middle of their external overlay instead of bottom left. In my opinion, this is a neutral change as the advantages from manufacturing and power consumption standpoints are clear, but so is the downside of losing the connection security that the Triomate sockets provided. Generally speaking, most people prefer the classic LED lock-lights alignment as well.

The PS/2 and USB controller cards differ. The PS/2 controller followed the same trend as Unicomp-made Model M13s and went for a two-card approach of using a standard 42H1292-type controller card for the keyboard and a separate larger controller card for the pointing stick. The pointing stick controller card also connects the keyboard-to-host cable and passes through the keyboard signal into it. The controller card observed in a 2004 PS/2 EnduraPro is P/N 01U0210, which has also been observed in Unicomp Customizers and Classics as late as 2013 and you can see a clearer photo of such a controller here. P/N 01U0210 has a P/N 01U0401 chip with a copyright date of 2001 - I could not find a datasheet for this chip, but it replaced the earlier P/N 1428578 used during the Lexmark era. Unicomp has at least indicated that it's a proprietary part though^[24][24]
pex - If you have questions about Model M internals, ask now. Project progress here. [accessed 2022-10-31].. PS/2 EnduraPros retain a PS/2 mouse passthrough port although I'm unsure if its daughterboard is the same or revised at some point.

The pointing stick controller card is positioned behind the keyboard assembly and is difficult to see without risking damage as the keyboard assembly is stuck onto the back case piece, thus photo of such a card from a period Unicomp-made Model M13 is substituted above. The pointing stick controller card accepts a 6-pin keyboard-to-host cable, a 4-pin cable from the keyboard controller card, a 5-pin flex cable from the pointing stick itself and a 4-pin flex cable from the mouse buttons.

The USB EnduraPro controller card of today is a unified single-board setup, based around a Cypress CY8C24493-24LTXI microcontroller. The chip is a part of their Programmable System-on-Chip (PSoC) family. I'm not sure when it was first released, but the earliest date I can find mentioned is 2013^[25][25]
Cypress - PSoC® Programmable System-on-Chip CY8C24X93 [accessed 2022-10-31]., meaning there must be another USB controller card setup that has eluded me thus far. Anywho, their current controller card is shared with pretty much all current USB Unicomp keyboards (excluding the Mini Model M) regardless of pointing stick presence. On Unicomp Classics, Ultra Classics, SpaceSaver Ms and New Model Ms, the pointing stick flex cable's would-be socket is simply absent. An interesting thing to note is that there's no socket for the mouse buttons, which have now been integrated into the keyboard's membrane itself!

Simplfying into Ultra Classic

Eventually, I guess Unicomp realised that there is probably a market in selling the EnduraPro without a pointing stick as a space-saving alternative to the Unicomp Customizer/Classic (the continuation of the IBM Enhanced Keyboard, the classic Model M). They did in fact make "takes 20% less space" as a selling point when they first introduced the keyboard... At the end of 2006, Unicomp put that realisation to use.

As early as 16th November 2006, Unicomp added a store page for a version of the EnduraPro without an integrated pointing stick for $69.99 (~$94 in 2021 money) with both USB and PS/2 versions available at launch but only in the raven black body/metallic grey keycaps colour scheme. At this point, the page is still titled "EnduraPro"^[26][26]
Unicomp - EnduraPro [accessed 2022-10-20]. License/note: retrieved via Wayback Machine (2006-11-16 capture)., as if Unicomp was still planning to use the "EnduraPro" brand as a family name rather than a single product name or the page was still under construction and the Wayback Machine just happened to index it before completion... By 8th December 2006, the SpaceSaver name was adopted^[27][27]
Unicomp - SpaceSaver [accessed 2022-10-20]. License/note: retrieved via Wayback Machine (2006-12-08 capture)..

Despite the name, it's of course very different to the much-beloved IBM Space Saving Keyboard (Model M SSK) or IBM Space Saver Keyboard (Model M4-1) designs but it would have technically been accurate considering Unicomp's lack of SSK-like keyboard during this time. This original name for what's now known as the Ultra Classic stood for about 6 years. By 26th April 2011, Unicomp made an Apple Mac OS X (now simply macOS) centric version named the SpaceSaver M^[28][28]
Unicomp - ibm keyboards, clicky keyboard, model m [accessed 2022-11-07]. License/note: retrieved via Wayback Machine (2011-04-26 capture). with various unique legends (compared to other Model Ms) for in particular iTunes and Safari controls and of course command keys. The standard SpaceSaver was then known as the SpaceSaver PC^[29][29]
Unicomp - Unicomp Keyboards [accessed 2022-11-07]. License/note: retrieved via Wayback Machine (2011-06-26 capture).. When Unicomp debuted their new storefront to replace their then-current Yahoo-based one, they renamed the SpaceSaver PC to Ultra Classic by 5th April 2012^[30][30]
Unicomp - Ultra Classic [accessed 2022-11-07]. License/note: retrieved via Wayback Machine (2012-04-05 capture).. Despite the PC version of the keyboard's name being changed, SpaceSaver M retained its name to this day.

Since then, Unicomp has notably introduced two new flavours of Ultra Classic. Firstly, a large font raven black Ultra Classic for people with hard of sight in 2014^[31][31]
Unicomp - Ultra Classic Large Font Black / Brilliant White [accessed 2022-11-07]. License/note: retrieved via Wayback Machine (2014-02-09 capture). and a Sun Unix version under the SpaceSaver moniker in 2015^[32][32]
Unicomp - Sun Unix SpaceSaver USB Keyboard [accessed 2022-11-07]. License/note: retrieved via Wayback Machine (2015-02-16 capture)..

There's honestly not a lot more to say about these. Anticlimactic I know, but that's the truth. Nevertheless, we can clearly see what structural changes Unicomp implemented on the Ultra Classic. Other than the obvious lack of a pointing stick, the main noticeable difference is the blanking plate in place of the mouse buttons. Well, more like it was filled in during production as it isn't a removable piece of plastic. Thankfully, unlike the mould fill that Unicomp initially added in place of the 5576-C01's large rotating standard, this fill is textured to match the rest of the case. Also due to the lack of pointing device electronics support, I don't think I've seen any PS/2 Ultra Classics with a PS/2 mouse passthrough port present.

...and the real changes simply end there. It uses the same controller card as most other Unicomp keyboards and the same internal assembly as the EnduraPro. It is what it is - an EnduraPro without the pointing stick. Surprised?

The keyboards today

If you look on Unicomp's store page for the Ultra Classic, it will boldly state the following at the time of writing:

Unicomp has effectively deprecated the Ultra Classic and now only offers a small selection of highly specific Ultra Classics such as the large font raven black Ultra Classic and the Sun Unix SpaceSaver shown in the last section. The aforementioned New Model M has displaced the Ultra Classic as the go-to reduced bezel full-size Model M, and when I did my review of the New Model M back in February 2021, I specifically compared the two and explained why the New Model M is a "better product" as Unicomp admits. The EnduraPro, whilst suffering from some supply issues due to the COVID-19 pandemic and its aftermath, is supposed to remain on sale since it has no like-for-like replacement but it's also showing its age. I've made some observations on both the EnduraPro and Ultra Classic, their current condition, and popular opinion on them.

The moulds are very old at this point and have degraded to some degree. They haven't degraded to the point that it compromises actual operation - EnduraPros and Ultra Classics are still solid keyboards that type well - but you can notice some blemishes in the form of noticeable small circles or streaks of discolouration, especially on raven black models. A few issues have developed around the mouse button area too; it seems a piece of the mould has broken and patched at some point since the thin piece of plastic separating the mouse button area and the keys is rough. Comparing the 2004 and 2019 EnduraPros shown before highlights this pretty easily.

Both designs don't really follow the traditional Model M design language. This would have been fine for the 5576-C01 as it was a very specific niche product, but the EnduraPro and Ultra Classic are primarily sold to western markets where the Model M has always had a strong design identity. As I said in my New Model M review, the ridge on top and lack of debossed line around all the outer keycaps almost make the keyboard unrecognisable as a Model M. I've heard people take issue with how the keys near the top of the keyboard (specifically just above the alphanumeric and numeric keypad areas) are sunken into the case, but the absolute top keys (Esc, F-keys, etc.) and the absolute bottom keys are raised above the case.

For the EnduraPro specifically, the FSR pointing stick has become somewhat notorious. I have no doubt the pointing stick was fine back in the day. According to W3Schools' statistics, 71% of recorded viewers used a screen with a resolution less than 1024x768 in 2000 and it wasn't until 2004 that 1024x768 became dominant^[36][36]
W3Schools - Browser Display Statistics [accessed 2022-11-04].. The FSR pointing stick was in fact designed even earlier than that, first making its way to Lexmark's M13s in 1992! Today, 1366x768 to 1920x1080 are the dominant resolutions on desktops and how it accelerates just isn't good enough for most people.

I think it's fair to say the EnduraPro/Ultra Classic family of keyboards are simply outdated. They're certainly not literally bad keyboards, just showing signs of age. I appreciate how honest Unicomp is about these keyboards on their storefront. Indeed, the New Model M is on a completely different level - it's clean, slick, and retains traditional Model M design elements whilst still saving space with its smaller side bezels and SSK-based profile. I recommend the New Model M as the go-to no-frills buckling spring keyboard.

But, I'm a fan of history and I've really enjoyed my time tinkering and exploring the story of the 5576-C01 and its descendants. You don't have to be a fan of the design or the FSR pointing stick, but I hope that after reading this, you can appreciate their history, longevity, and how they tie into the IBM keyboard/Model M/buckling spring story! They certainly played a role in carrying buckling springs into the 2010s past times when few people cared about them.

Cheers!

Sources

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