IBM PS/2 Note N33 Pre-ThinkPad IBM Portables

IBM PS/2 Note N33 SX & N51 SX

Machine Types 8533 / 8551 · 1991-93 · 5 sections

The AT-bus N33 SX and MCA-bus N51 SX from IBM's PS/2 Note line, announced March 1992 — half a year before the first ThinkPad — and modelled on the PS/55 Note IBM had released in Japan in April 1991.

Related Documents

Service Reference

Product Overview #

4 variants of this machine type, side by side. A cell spanning several columns is shared by those models, so the narrow cells are the differences — memory type, battery chemistry and panel are what usually change across a range.

Spec PS/2 Note N33 SX (12MHz) PS/2 Note N33 SX (16MHz) PS/2 Note N51 SLC PS/2 Note N51 SX
Released June 1991 March 1992
Processor CPU Type: Soldered QFP
Intel 386SX @12MHz		 CPU Type: Soldered QFP
Intel 386SX @16MHz		 IBM 386SLC @16MHz Intel 386SX @16MHz
Chipset Western Digital WD76C10 —
Bus AT Bus Micro Channel
Memory Type: 1x 72-pin SIMM slot
Standard: 2MB Soldered
Maximum: 6MB		 Type: 1x 72-pin SIMM slot
Standard: 2MB
Maximum: 6MB		 Type: SIMM
Standard: 2MB
Maximum: 10MB
Storage 2.5" IDE
Standard: Optional		 2.5" IDE
Standard: 40 or 80MB		 2.5" ESDI
Standard: 80MB		 2.5" ESDI
Standard: 40MB
Display 9.5" Passive Matrix Grayscale LCD @640x480 9.5" Passive Matrix Grayscale (16 shades) LCD @640x480
Graphics Western Digital WD90C20 VRAM: 256KB —
Audio PC Speaker
Main battery NiCad 2x NiMH Batteries 2x NiCad Batteries
CMOS battery Lithium CMOS Battery (Barrel)
NiCad Reserve Battery (Stick)		 — Proprietary Lithium CMOS Battery
NiCad Reserve Battery
Power supply Barrel Jack —
Media drives Internal 3.5" 1.44MB Floppy Drive on models with no hard drive, otherwise external 3.5" 1.44MB Floppy Drive
PC Cards None
Networking None Modem (Optional)
Ports 1x Parallel
1x Serial
1x PS/2
1x Expansion Bus Port		 1x Parallel
1x Serial
1x VGA Out
1x PS/2
1x Expansion Connector		 1x Parallel
1x Serial
1x VGA Out
1x PS/2
1x Microchannel Expansion Bus Port
BIOS IBM
Pointing device None

PS/2 Note N33 SX #

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. 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). 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.

External Resources & References

PS/2 Note N51 SX #

The PS/2 Note N51 SX (or PS/2 Model N51 SX) 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.

N51 System Board (Top View) #

  1. LCD Interface Connector
  2. System-Expansion Port (120-pin)
  3. Keyboard-Control Card Connector
  4. Battery Presence Switch
  5. LCD Interface Connector
  6. LCD Interface Connector

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N51 System Board (Bottom View) #

  1. I/O Panel Connector
  2. Voltage Converter Connector
  3. System Expansion Port (120-pin)
  4. Password-Override Connector
  5. Memory-Module Kit Connector
  6. Hard-Disk Drive Connector
  7. Voltage Converter Connector
  8. Hard-Disk Drive Connector
  9. Diskette-Drive Connector
  10. Diskette-Drive Connector
  11. I/O Panel Connector
  12. I/O Panel Connector

d2na0335