IBM Thinkpad 235

Details: Published: 26 April 2025

This is one of my IBM Thinkpad 235 machines, imported from Japan. 235 machines tend to be in lovely condtion and well-kept by their owners.

The 235 came about after a joint project called RIOS with RICOH - a Japanese electronics company, and IBM, created a series of ultraportable machines and in this case, it was the Chandra which was licensed to a number of notebook manufacturers to sell as their own design. IBM released their own but it was upgraded and known as the Chandra-II or the Clavius. All these nicknames came from the movie 2001: A Space Odessey.

RIOS has brought us the Thinkpad 200, The Palmtop PC110, and Thinkpad 220 and 230Cs.

The 235 was the final IBM Thinkpad from the RIOS venture, which is why the 240 machine is larger and takes the range in a new direction entirely.

These ultra mobile computers gained a wide following in Japan where miniturisation was extremely popular, in many cases being more popular and widely known than the 700C.

I acquired one of Ricoh's own Chandra laptop, snappily called the NP-30J, which was originally non-functional. After a teardown and recap, I was able to bring the machine back to life. The Ricoh model is of noticably lower spec with a slower CPU and lower resolution screen, but it's still a lovely machine to hold and use.

For a little fun, I compared the sizes of the 235 and 535X models because, although both ranges were small, sometimes, they really weren't all that different in size.

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PS/note (2141-182)

This rather unusual US-designed PS/note feels like an experiment in case and PCB design. It has it's own unique design flairs, badge, internals and case. This was in a world where the US and Japan were each competing for IBM's value range of notebooks which were entirely distinct from the high-end business Thinkpad 700-series.

Most of these models were 25Mhz 386SL machines although there was a 386SX variant too. They came with 2Mb RAM, upgradable to 10Mb, and 85Mb 2.5" IDE hard drive and a 640x480 64-Greyscale passice LCD.

Spot the (almost) entirely unique square case badge, which some have attributed the style to alignment with IBM's PS/1 value desktop range. It's somewhat confusing because the original Japanese PS/55 note shares a similar name (and badged as simply a note) and indeed a lot of machines are also PS/notes with a suffix of it's specific model to provide easy referencing (in the West alone you had the PS/2 note N33sx, N51sx/slc, PS/note 425, a PS/note 45SL). It's like a team within IBM were trying to restart the note brand to the West by saying 'here is THE note'.

This type of case badge was only seen also in the probably unrelated PS/note N45SL design by Zenith, which became the Thinkpad 300.

As a result most people refer to this as the note 182.

Read more: PS/note (2141-182)

IBM External Floppy Disk Drives

Due to the different IBM labs and companies developing IBM portables and the time period over which they existed before USB, there are a lot of different types of IBM floppy drive.

Whilst we're only covering external here, there are at least 3 types of connector:

26mm / fattest: Found on the 701c

21mm: Found on the PS/notes, 850, 7xx tablets. 360, 365

17mm / Thinnest: Found on the later models which favoured optical drives built-in such as the 755CD, 760, 600 and various 3xx series. Ultraslim floppy drive.

21mm

This early floppy drive 66G5069, also known as "UltraBay Diskette Drive enclosure" actually contains the original multibay floppy within it's large outer shell. There are also fixed standard external 21mm drives.

These ultrabay floppy drives came in various models from various manufacturers, so externally each 66G5069 drive may look the same, but internally it could be totally different.

TEAC FD-05HG

Here we have a TEAC FD-05HG drive, which has one eletrolytic cap, which as far as I know should only be replaced with an electrolytic. I have had drive read issues by replacing these with a solid capactor. It's a 100u / 10v capacitor seen below:

You can get away, like I did with a 7.7m through-hole capacitor with the legs splayed outwards:

Whilst it's open you may (or may not) want to clean the magnetic heads with a little IPA and check the corkscrew spindle which moves the heads forward and back across the diskette is moving smoothly.

Even though this 7.7mm tall capacitor is longer than the original surface mounted cap, it still just fits under the floppy drive chassis - although you cannot go any more than this.

Sony MPF720-2

And here is another 1.44Mb ultrabay floppy drive - the Sony MPF720-2 (weirdly suggesting it's a 720Kb drive, but it's a 1.44Mb drive):

This Sony drive is similar, but you do not need to remove the little PCB in order to replace the 47uf capacitor:

In this case, small 6mm through hole capacitors with the legs splade are a good replacement:

750 Series

I've managed to restore an almost complete set of the 750 series machines. Here are some of the collection:

Read more: 750 Series

Translating PS/55 note Japanese keyboard to English keyboard mapping

If you connect a western keyboard to the earliest PS/55 and PS/55 N23 SX notes, the keyboard mappings are all messed up. Here is a rough map of what key is mapped to what real keypress:

Read more: Translating PS/55 note Japanese keyboard to English keyboard mapping

IBM 5535 Multistation

IBM Japan had a range of Kanji-character-enabled desktop computers, called the Multistations. This was part of that family with the addition of a greyscale LCD display. Although 5535 is the 'laptop' range of machines, With the sheer size and weight (7kg), I think you would consider it more like a 'space saving desktop', much like the IBM Convertible. It has a sibling called the 5535-S which has a slightly different design and is 'less boxy'.

Read more: IBM 5535 Multistation