
Released in 2005, the T43 was the last official ThinkPad before Lenovo was brought into the picture. This meant that the T43 was the last ThinkPad to have preferable 'awkward' features such as: omitting the Windows keys, native OS/2 support & drivers, a characteristic colour scheme, the 'Access IBM' button, IBM BIOS splash screen etc.
Downloads
Manuals
Firmware, Drivers, & Software
To IBM or not to IBM
While it has been hotly debated whether or not the T43 is a 'true' IBM ThinkPad (since the PC division was sold just a few months before the T43 went into production), IBM refers to the T43 as an 'IBM ThinkPad' and by the time Lenovo purchased the PC division the T43 would have been largely or fully completed borrowing designs largely from the T42 to accelerate production and reduce costs (which is why the majority of T4x components are cross-compatible). Furthermore, the T43 has the aforementioned features that Lenovo would never in a million years agree to or implement; this explains why the T60 *immediately* introduced a Windows key and dropped OS/2 support (entirely Lenovo's doing and not IBM's). So while Lenovo bought the PC division in midst of the T43, the transition was a lot slower while IBM had to hold onto promises for large corporate clients and honour a lot of legacy features (OS/2). We can take this even further, in the January 19th 2005 T43 hardware announcement it clearly states ThinkPad is a trademark of IBM and not Lenovo:
Trademarks: Ultrabay, ServiceSuite, and UltraNav are trademarks of International Business Machines Corporation in the United States or other countries or both. ThinkPad, OS/2 Warp, TrackPoint, Lotus SmartSuite, Lotus Notes, HelpCenter, and ServicePac are registered trademarks of International Business Machines Corporation in the United States or other countries or both.
So with all of that weighing in, I believe it safely douses the rumour that post 2003 ThinkPads are Lenovo and not IBM. Technically 2006 is when Lenovo started to act, and it's worth noting that Lenovo actually used some of IBM's designs in a mutual relationship (for instance, IBM allowed Lenovo to use their IntelliStation M Pro 9229 chassis in a watered-down state for the Lenovo ThinkCentre lineup, but that's another story for another day).
Who Needs Winkeys?
While on the topic, it hasn't been too widely discussed why IBM omitted the Windows keys from the (majority) of their ThinkPad line especially considering the T43 was being manufactured well into 2006; which is an almost unthinkable act. Here are a few of my personal speculations, but I believe it largely revolves around the fact Microsoft was resorting to illegal and distasteful practices (when attacking OS/2 and people involved with it) leading IBM to reduce their footprint on anything with a Microsoft logo:
After the assessing the following list, it's most likely a combination of multiple reasons (I think it has to do with practicality, it's not practical compromising the keyboard for meta keys that were rarely used back then and caused issues with full-screen DOS applications). It's very important to note that only when Lenovo was involved with ThinkPad development did the Windows key appear. At that point Lenovo didn't wish to hold onto aged IBMisms that reduced the ThinkPad to a more niche 'power users' market versus the mainstream, but the flipside is that the ThinkPad never really was a 'mainstream' product in the traditional sense. Lenovo is actually facing this problem now where they've alienated their power users, and aren't selling any ThinkPads to the mainstream users. The backlash when Lenovo removed the TrackPoint buttons was immense and they eventually had to add them back in. Another thing to note is that IBM was one of the few companies that actually built laptops when they still weren't as common as they are now. I'd say this is no longer relevant as Lenovo has attempted to fix many of their weird problems like the "clunkpad" nobody wanted, and tried giving one last olive branch from the "25th anniversary" edition.
What Operating System for the T43?
Due to the aging hardware in the T43 series, they're not as effective at running newer operating systems like Windows 7 or Windows 10, but it is possible to install those. Many people will relegate back to XP, however due to all of the security issues, NSA back doors and general lack of support now--XP is just not a good operating to run in my opinion (although I've never particularly liked XP; my favourites are Windows 98 and Vista, between the two you get better support for software than XP). The best options would be OS/2 (or preferably ArcaOS) or some distribution of Linux that still supports 32-bit CPUs, Linux is starting to really crack down on retiring older hardware though as it becomes less feasible to maintain. And as time goes on, the security issues with Windows 7 and above will continue to get worse.
Installing OS/2 Warp 4.52 on a T43/T43p
Note: OS/2 Warp 4.0 is not compatible on the T43, stick with 4.52. If you choose FAT instead of HPFS you will not have long filename support which limits what you can run on OS/2, on the flipside hibernation is only possible when you use FAT. OS/2 can only be installed to C:\, any other drive letter it will simply ignore.
If you purchase ArcaOS, a lot of these legacy-based headaches and issues with OS/2 Warp 4.52 are mitigated and also allows you to install the OS from a single USB stick. Another big thing is that ArcaOS allows OS/2 to run on Intel-based T43s via the panorama video driver. Obviously it won't be as good as a more capable ATI GPU with SciTech SNAP, but at least it's now an option--and you won't have to deal with the potential problem of desoldering ATI GPUs.
GPU Desoldering Issue
There can be a problem with a T43 (and T42) that eventually develops issues with the BGA connection. In this situation you will have to either re-heat the ATI GPU (less successful) or desolder the chip, reball it, and solder it down (more successful). I'd suggest independently researching the techniques involved on repairing this as there's many ways either can be achieved--and both methods will involve purchasing additional equipment.
Alternatively, you can always purchase a T41, 42 or 43 motherboard to replace it.
T43 Keyboard Variances
IBM, like with most of the ThinkPad series, contracted to three manufacturers so that they could always have a supply of keyboards for meeting delivery requirements. This stems from IBM's original corporate mandate of having a minimum of two supplies for any given part. The T4x series uses different FRUs depending if you have a 14.1" or 15" model, later the T60 series would just use a single keyboard for all different sizes. Because each manufacture makes each keyboard slightly differently, they will feel different--and some prefer some manufacturers over others. Chicony is generally considered the worst-feeling.
English U.S. (ANSI), 15"
English U.S. (ANSI) 14.1"
ThinkPad Dock II

The T43 (and the whole T4x series) can make use of the ThinkPad Dock II, which is an advanced dock that also has a PCI slot for expanding to a better GPU, sound card, SCSI or other devices. The biggest problem I have with the dock is the irritating fan / however it should be possible to modify it with a better, quieter fan. I presently have a Matrox G450 PCI card in there for displaying a second video output -- at least GPUs are the most common addition in docks I think. Below is the driver since Matrox no longer has the full ISO available anymore:
Aside: if you put Windows or Linux on this, you could also install a GT 610 which would be one hell of a GPU to run with a T43.
Conclusion
Where does the T43 stand today? Its keyboard is slightly better than the T60's, and they have their own good repertoire of displays--they're even slightly more stylish than the T6x series. However the aging CPU and 2 GB of RAM places them a bit behind for web browsing (even though they can manage a valiant effort), this is no longer really valid as it was written a long time ago. T43s are useless for browsing the internet now, especially as 64-bit is a requirement for every browser. At this point both the T6x and T4x series have depreciating batteries so neither one has an advantage in that department anymore.
Specifications
----CPU Options----
*Intel Pentium M, Dothan
----Audio----
*SoundMax
----Video----
*Intel Graphics, ATI Mobility, ATI FireGL
----Memory----
2GB is the maximum allowed memory by the memory controller (the usual intel memory controller crippling). However this really isn't a problem for OS/2.
