IBM 5120
Introduced:February 1980
Price: US $9,340 with printer
Weight:105 lbs / 48 kg
CPU:IBM proprietary
RAM:32K
Display:9-inch monitor
64 X 16 text
Storage:dual 8-inch floppy drives
Ports:floppy / printer I/O port
OS:APL and/or BASIC





IBM's lowest-priced computer to date (in 1980, that is).
Also the heaviest desktop computer ever - 105 pounds / 48 kg !

The IBM 5120 Computing System consists of the IBM 5110 Model 3 Computer, the 5114 external diskette unit, and the 5103 dot-matrix printer.

The 5103 printer is a wire matrix printer used by the 5120 computing system. The 5103 printer provides a hard copy of the data at a rate of 80 characters per second or 120 characters per second.

The 5114 diskette unit attaches to the 5110 Model 3 computer through the I/O channel; one 5114 unit can be attached to the 5120 computing system. The 5114 unit stores up to 1.2 megabytes of data on each diskette drive and may contain two drives.



On the front of the model 3 are controls to view the data registers, a system-reset switch, and monitor brightness. Internally there is a switch to select from normal or inverse video.


The card-cage is removed from the back of the system - the computer logic is contained on eight cards installed here.
These circuit boards are the same as those of the older IBM 5110, but the rest of the system is new and improved.



The IBM 5114 external floppy-drive cabinet contains one or two 8-inch floppy drives. They weigh 15 lbs each.
The entire cabinet weighs 132 lbs.


The IBM System/23 Datamaster was released just one year after the 5120 - it looks similar, but has an entirely different internal circuit design. Gone are the custom IBM ICs - the Datamaster is base on Intel technology.

Related Links

  • IBM 5120 from ibm.com
  • IBM 5120 from Digibarn Computer Museum
  • IBM 5120 from old-computers.com

    • Partial History of the IBM Computers

    • 1967: IBM builds the worlds first floppy disk.
    • 1967: IBM introduces the worlds first 8" floppy disk.
    • 1973: IBM introduces the IBM 3340 hard disk unit, known as the Winchester.
    • 1975: September - IBM's Entry Level Systems unit unveils "Project Mercury", the IBM 5100 Portable Computer.
    • 1981: September - IBM releases the IBM 5150 PC Personal Computer.
    • 1982: April - Eight months after the introduction of the IBM PC, 50,000 units have been sold.
    • 1982: May - Microsoft releases MS-DOS 1.1 to IBM, for the IBM PC.
    • 1982: June - The first IBM PC clone, the MPC, is released by Columbia Data Products.
    • 1982: August - After one year of production, IBM ships the 200,000th IBM PC.
    • 1982: November - Compaq Computer introduces the Compaq Portable PC, the first 100% IBM compatible. It cost Compaq US$1 million to create an IBM-compatible ROM BIOS that did not violate IBM's copyright.
    • 1982: At the West Coast Computer Faire, Davong Systems introduces its 5MB Winchester Disk Drive for the IBM PC, for US$2000.
    • 1983: March - IBM announces the IBM PC XT, with a 10 MB hard drive, 128KB RAM and a 360KB floppy drive. It costs US$5000.
    • 1983: November - IBM announces the IBM PCjr. It is US$700 for the bare configuration.
    • 1984: February - IBM introduces the IBM Portable PC.
    • 1984: March - IBM ships the IBM PCjr. It uses the 8088 CPU, 64KB RAM, and one 5.25-inch disk drive, but no monitor. It costs US$1300.
    • 1984: August - IBM announces the PC AT, for US$4000-6700.
    • 1985: April - IBM abandons production of the IBM PCjr.
    • 1986: April - IBM announces the IBM PC Convertible, 80C88-based, 256K RAM, and two 720K floppy disks, for US$2000.
    • 1986: April - IBM discontinues the IBM Portable PC.
    • 1986: September - IBM announces the IBM PC-XT Model 286, with 640KB RAM, 1.2MB floppy drive, 20MB hard drive, serial/parallel ports, and keyboard for US$4000.
    • 1987: IBM discontinues the IBM PC (model 5150) line.
      Source: Chronology of Events in the History of Microcomputers



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