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The IBM PS/2 Note and PS/note are a series of notebooks from the PS/2 line by IBM. It was announced in March 1992, half a year prior to the release of the first ThinkPad, the IBM ThinkPad 700. The series was discontinued in 1994.

• Background

• Models

• PS/55 note

• PS/55 note N23 SX

• PS/2 note N33 SX

• PS/ note C23 SX

• PS/2 note N51 SX

• PS/2 note N51 SLC

• PS/ note N45 SL

• PS/note T22 SX

• PS/note 182/E82/N82

• Model 425/425C

• Accessories

• Discontinuation

• Timeline

• References

• External links

After the departure of Bob Lawten from IBM, the team at IBM had little development direction after the IBM PS/2 L40 SX. James Cannavino pushed for the new notebook series, which fell behind schedule.cite-ref-1[1] The N45 SL, N51 SX and N51 SLC were announced on the same day as the IBM PS/2 (color laptop) CL57 SX. During this time there was a distinction between notebooks and laptops, where the former are A4 sized and the latter are larger.

The notebooks were modeled after the PS/55 Note which was released by IBM in Japan in April 1991.cite-ref-2[2]

| IBM PS/55 note, PS/2 note, and PS/note models | IBM PS/55 note, PS/2 note, and PS/note models | IBM PS/55 note, PS/2 note, and PS/note models | IBM PS/55 note, PS/2 note, and PS/note models | IBM PS/55 note, PS/2 note, and PS/note models | IBM PS/55 note, PS/2 note, and PS/note models |

|---|---|---|---|---|---|

| | | 1991 | 1992 | 1993 | 1994 |

| PS/2 note | | N33 SX | N51 SX; N51 SLC | | |

| | | | | | |

| PS/note | | | 182; E82; N82 | 425/425C | |

| PS/note | | | N45 SL | | |

Simply branded as PS/55 note, the type 5523-S0x was the first Japanese notebook from the 55-series with a 12Mhz 80386 CPU, 2Mb RAM built in and a 9.5" 16-greyscale VGA LCD (640x480). It was only released in Japan. The two main planars inside consisted of two separate boards "APEX-MAIN" and "SUB-BOARD" leaving room inside for either a floppy drive or a hard drive - but not both. The keyboard has a 7-row layout only. It was not common for IBM to add codenames or words to their internal PCBs, suggesting some influence from outside IBM.

This was a second generation PS/55 note type 5523-S1x with N23 SX added to its case badge and also only released in Japan. This machine had a 16Mhz 80386 CPU and a redesigned motherboard consisting of just one planar. The additional space inside meant the machine could accommodate both an internal floppy disk drive and a hard drive. It also featured an external VGA output and display invert switch.cite-ref-3[3] The main planar inside has "EXCEL-MAIN" written on it.

The PS/2 Model N33 SX (also known as PS/2 note N33 SX) was the first Western-released notebook-sized computer from IBM which was announced in 1991.cite-ref-4[4] This model was based on the AT-bus and had between 2 or 6MB RAM. It has a 9.5" 16-greyscale VGA LCD (640x480), external 1.44MB floppy connector, expansion ports and a 40MB or 80MB HDD, and weighs 5.5 lb (2.5 kg).cite-ref-5[5] There were two versions with one based on the original Japanese 12Mhz PS/55 Note and the other based on the Japanese 16Mhz N23 SX. The main two changes is that neither had internal floppy drives and they both had a Western keyboard.

A joint third generation PS/Note took the ISA-bus N23SX and added a 10.4" colour TFT panel from the CL57, but successfully miniaturised to fit within the smaller notebook lid. They were branded 'Thinkpad' on the colour IBM logo.cite-ref-6[6]

The joint third generation PS/2 Note N51 SX (or PS/2 Model N51 SXcite-ref-7[7]) was a low-end mainstream notebook with the new MCA bus, which contained a slower version of the typical 386SX found in other notebooks. The N51 SX was delayed for months.cite-ref-1-8-0[8]

The PS/2 Note N51 SLC (or PS/2 Model N51 SLC) was based on IBM their 386SLC.cite-ref-1-8-1[8] This MCA-bus model has a PS/55 note sibling.cite-ref-9[9]

Manufactured by Zenith, the PS/note N45 SL was priced at $2,045 and contains a 25 MHz 386SL. It had 2MB RAM and an 80cite-ref-0-10-0[10] or 120MB HDDcite-ref-11[11] and was equipped with only 6-row keyboard without dedicated navigation block, the similar layout as a low-end ThinkPad 300 laptop.

PC Mag considered the display a disappointment, but noted its good design and performance.cite-ref-0-10-1[10]

It was manufactured by Zenith Data Systems.cite-ref-12[12]

The T22 SX is an unusual non-backlite greyscale tablet and detachable keyboard offshoot from the main note range. It sold in small numbers.

A side project with Lexmark, the PS/note 182 and PS/note E82 was equipped with 80386SL CPU, PS/note N82 was equipped with 80386SX and released in 1992. This line has a 7-row keyboard layout and similar to next-year PS/note 425 model case (but with gray case color and without TrackPoint). The case badge uniquely resembled the style of the PS/1.

The PS/note 425/425C are identical to the ThinkPad 350/350C.cite-ref-13[13]

• Communication cartridge

• Communication cartridge II cite-ref-14[14]cite-ref-15[15]

• External floppy disk drive

• External numpad

In March 1994, it was reported that IBM would consolidate the PS/note series into the ThinkPad 300 series.cite-ref-16[16] In May 1994, the ThinkPad 360 series was released.

| Timeline of the IBM Personal Computer |

|---|

| |

| Asterisk (*) denotes a model released in Japan only |

cite-note-11. ↑ citerefa-2000A., Dell, Deborah (2000). ThinkPad: a different shade of blue. Sams. p. 84. ISBN 0-672-31756-7. OCLC 781169669.{{cite book}}: CS1 maint: multiple names: authors list (link)

cite-note-22. ↑ citerefscannell1991Scannell, Ed (23 Dec 1991). "IBM readies 6 portables". InfoWorld.

cite-note-33. ↑ citerefmaggs2025Maggs, Alexander (April 2025). "IBM PS/55 Note N23 SX (5523-SC4) - Japan". Ret Rocks.

cite-note-44. ↑ "IBM PS/2 Note - Computer - Computing History". The Centre for Computing History. Retrieved 2021-04-20.

cite-note-55. ↑ citerefname1992Name (1992-02-25). "IBM UK LAUNCHES COLOUR LAPTOP AS WELL AS NOTEBOOK". Tech Monitor. Retrieved 2021-04-18.

cite-note-66. ↑ "PS/55note C23V (5523-V2/VJ)". Ardent Tool Of Capitalism.

cite-note-77. ↑ "Personal System/2 Models N51 SLC and N51 SX" (PDF).

cite-note-1-88. ↑ citereffitzgerald1992Fitzgerald, Michael (1992-03-30). Going down in history. IDG Enterprise. p. 38. {{cite book}}: |work= ignored (help)

cite-note-99. ↑ "PS/55note N51SLC 8551-S08". www.mars.dti.ne.jp. Retrieved 2021-05-18.

cite-note-0-1010. ↑ "IBM PS/note N45sl". PC Mag. Ziff Davis, Inc. 1992-12-22.

cite-note-1111. ↑ "PS/note N45 SL" (PDF).

cite-note-1212. ↑ "PS/2 Model N33 SX". Ardent Tool of Capitalism. Retrieved 2021-04-19.

cite-note-1313. ↑ Hardware Maintenance Manual Volume 1: Laptop, Notebook, Portable and ThinkPad Computers (PDF). p. 205.

cite-note-1414. ↑ "8551 - PS/Note N51". Archived from the original on 2020-08-14.

cite-note-1515. ↑ "IBM Personal System/2 Communications Cartridge II" (PDF). kev009.com.

cite-note-1616. ↑ citereflee1994Lee, Yvonne (21 March 1994). "IBM revamps line with four ThinkPads". InfoWorld.

• Thinkwiki.de - N33SX

• Thinkwiki.de - N45SL

• Thinkwiki.de - N51

• Comparison between PS/Note Model 425 and ThinkPad 350C