IBM Convertible PC
Model:5140 "Convertible"
Released:April 1986
Price: US $1,995
Weight:12 pounds / 5.5 kg
CPU:Intel 80C88 @ 4.77 MHz
RAM:256K, 512K max
Display:LCD - 80 X 25 text
640 X 200 graphics
Storage:two internal floppies
3-1/2 inch, 720K each
Ports:expansion bus
Peripherals:thermal printer
serial, parallel ports
CRT display adapter
Power:12vdc, pin +
OS:PC-DOS 3.2, BASIC






IBM's first laptop computer is a big improvement over their earlier portable computer, the giant IBM Portable PC from 2 years earlier in 1984.

Is the IBM 5140 "Convertible" really a convertible? Yes - even the top (display) comes off.

Why would you want to remove the LCD display? With the CRT Display Adapter attached, you can use an external monitor instead.

The Convertible has no standard expansion ports - you can install an internal modem ($450), and on the back is the system bus for the optional adapters to be installed.
These include:
  • thermal/ribbon printer - $295.
  • serial/parallel adapter - $195.
  • CRT display adapter (640 X 200) - $350.
    • All of these adapters "convert" the Convertible into a more useful machine, but with all of them installed, the system grows an extra 7 inches in length and the weight increases from 12 pounds to 20 pounds, making it rather long and unwieldy, to say the least.

    The Convertible comprised many firsts for IBM -
  • their first computer to run on batteries.
  • the first IBM computer to have 3.5-inch floppy drives.
  • their first use of Surface Mounted Devices in a computer.

    • Normally the Convertible would run PC-DOS 3.2 or later, but if you power-up without any disks installed, it will default to the BASIC programming language.

    The original LCD display on the Convertible had poor contrast and was difficult to read. It was replaced by a higher quality version, and finally a very nice backlit version, as seen here to the left.



    Related Links

  • IBM 5140 from Louis Ohland's pages
  • IBM 5140 from Upgrading & Repairing PCs.
  • IBM 5140 from The History of Computing Project (THOCP)
  • IBM 5140 from The Computer Closet

    • 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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