IBM Personal Computer (PC)
Released:September 1981
Price: US $1,565 ~ $3,000
CPU:Intel 8088, 4.77MHz
RAM:16K, 640K max
Display:80 X 24 text
Storage:dual 160KB 5.25-inch disk drives
Ports:cassette & keyboard only
5 internal expansion slots
OS:PC-DOS v1.0

The IBM Personal Computer ("PC") was not as powerful as many of the other personal computers it was competing against at the time of its release. The simplest configuration has only 16K on-board RAM and uses an audio cassette to load and save data - the floppy drive was optional, and a hard drive was not suported.

A basic system for home use attaches to an audio tape cassette player and a television set (that means no floppy drives or video monitor) sold for approximately $1,565. PC-DOS, the operating system, was not available on cassette, so this basic system is only capable of running the Microsoft BASIC programming language, which is built-in and included with every PC.

A more typical system for home or school with a memory of 64K bytes, a single diskette drive and its own display, was priced around $3,000.

An expanded system for business with color graphics, two diskette drives, and a printer cost about $4,500.

Five internal ISA expansion slots on the motherboard provide the ability to add additional memory and other capabllities, although one slot is usually occupied by the video card, and another by the optional floppy drive controller. A third slot typically has an RS-232 serial port card installed. A modem card for dialing-up remote computer systems became a popular option as well.

Although the original IBM 5150 "PC" supported only 64K of RAM memory on the motherboard, later versions used higher capacity memory chips, allowing up to 256K onboard - up to 640K with internal expansion cards.

The high quality (and very noisy) keyboard is the same as the IBM Datamaster, a business computer released earlier in the same year as the "PC".

The 5150 "PC" wasn't IBM's first attempt at a compact, stand alone computer, although it is by far their most successful.
  • In 1975, the model 5100 was an entirely self-contained, portable computer system - probably the first ever.
  • Developed between 1979 and 1981, the Datamaster was an all-in-one desktop system for word processing.

    These two earlier attempts were directed at engineering and high-end business, were very expensive and sold poorly.

    For the "PC', in order to save time and money, instead of developing their own hardware and software, IBM used already available off-the-shelf components. The CPU was from Intel, and the operating system (OS) was by Microsoft, who licensed it to IBM as PC-DOS.

    Other companies could in theory obtain these same components and create their own version of the PC, and cut into IBM's market. But there was one aspect of the PC which could not be legally copied - the BIOS, as it was copyrighted and protected by law. But Compaq and the others eventually found a legal but 'dishonest' way to duplicated that as well, opening the floodgates to cheaper but still compatible IBM clones.

    Actually, there is a bug in Microsoft's floating-point math routine of the PC's BASIC ROM chip. If you ask the system to divide 0.01 by 10, it displays 9.999999E-4, instead of the correct answer of 0.001.

    Although not necessarily the best machine by technological standards, IBM's expertise and the fact that the IBM PC actually looks and feels like a professional computer system made the IBM PC and subsequent PC clones extremely popular. They have evolved into today's so-called Wintel (Windows + Intel) computer systems, used world-wide.

    Related Links

  • IBM 5150 from

  • Partial History the IBM PC

    • 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 ships 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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