PS/55 Note (1st Generation)

Details: Published: 12 May 2025

This was the first mass-market (well - Japan!) IBM Notebook - specifically a seperate model line to the type 5535 laptop models, which is why they simply badged it with 'note'.

The first generation PS/55 notes had the type 5523-S0x

It's design and specification was followed by a re-release later with the Internationally-released 12Mhz N33, but without the Japanese 7-row keyboard.

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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'.

IBM PS/2 Model CL57 SX

This is a massive, stange, outlier in IBM's journey into portable personal computers. CL for 'Color Laptop' and 57 for....... fuck knows. The type is 8554 and it runs MCA bus. It's almost completely unique although it shares a look similar to that of the possibly-vaporware, Japan-only PS/55 Power (PC) Laptop EWS - which also feels like a skunkworks project.

Some sources state this machine started as a Model N27sx - a 'for fun' IBM Japan design for domestic japanese market. I can't find much source material that this is true though. Apparently, the CPU was downgraded from a 486 to a 386 so as to not compete with other PS/2 machines. Supposedly there are some hidden clues on the machines that despite it's international 85xx model designation, the plant ID is 97 which is IBM Japan Entry Systems factory in Fujisawa.

PS/55 Note N51 SX and SLC

After the successes of the original note (1st Gen), the N23 (2nd Gen) and the N33 machines, two machines share the third generation space - the still-monochome MCA N51 and TFT Colour, ISA C23V.

Notes on notes

Note: The 5499 On-Line note isn't really part of the brand note family. Whilst it's certainly a notebook, it's a weird dead end portable terminal which has very little use unconnected to a maintrame.

PS/55 note - The PS/55 was a range of Type-55xx computers for only Japan. They're based on the PS/2 but ISA bus and with special Japanese localisations supporting the more technically difficult languge to display on screen and type on a keyboard.

The 'note' branding was devised for the Notebook versions and within Japan all had to be in the 5523 model range (as opposed to 5535 for laptops). The original (or 1st Generation) 12Mhz PS/55 Note was the 386 5523-S0x model with sandwiched planars and room for either a FDD or HDD.

PS/55 Note N23 SX (2nd Generation)

The N23 name comes from this machine's model type 5523. It was the second generation PS/55 Note (the 55xx series in Japan being similar to the Western PS/2 series). The first generation PS/55 Note didn't have room for both a floppy drive AND a hard drive, so you picked either as an option. The motherboard has the same EXCEL codename as the N33 16Mhz.