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Zenith Z 100

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Manufacturer
  
Zenith Data Systems

Type
  
personal computer

Release date
  
June 1982; 34 years ago (1982-06)

Operating system
  
Available with CP/M and Z-DOS (non-IBM compatible MS-DOS variant)

CPU
  
Dual processors: 8085 and 8088

Memory
  
Base 128 KB RAM, expandable to 192 KB on board, to 768 KB with S-100 cards. (Video RAM was paged into the 64 KB block above 768 KB).

The Z-100 computer is an early personal computer made by Zenith Data Systems (ZDS). It was an alternative to the hardware system that won the marketing shares war in the early to mid-1980s, the IBM PC/XT/AT succession or family of computers.

Contents

Design

The Zenith Data Systems Z-100 was a pre-assembled version of the Heathkit H100 electronic kit. Configured as a family (Z-120 was an all in one model, with self-contained monitor), the Z-110 (called the low profile model) was similar in size to the cabinet of an IBM PC, XT, or AT, but a bit shorter, and configured with a raised cabinet molding on the top surface within which one placed one's display monitor, designed to keep it from sliding off to either side or back. Both models had a built in keyboard that was tactilely and in appearance modeled on an IBM Selectric typewriter, the premier office machine of the day.

  • Dual processors: 8085 and 8088.
  • Available with CP/M and Z-DOS (non-IBM compatible MS-DOS variant).
  • Five S-100 expansion slots.
  • Two 320 KB 40-track double-sided 5.25-inch floppy disk drives. Socket enabled direct plug-in of external 8-inch floppies.
  • 2× serial ports (2661 UART), one Centronics printer port (discrete TTL chips), light pen port.
  • 640×225 bitmap display. 8 colors (low-profile model), or monochrome upgradable to 8 greyscales (all-in-one).
  • Base 128 KB RAM, expandable to 192 KB on board, to 768 KB with S-100 cards. (Video RAM was paged into the 64 KB block above 768 KB).

    • The Z-100 was a "near-compatible" system to the IBM PC, using standard floppy drives. It ran a non-IBM version of MS-DOS, so "generic MS-DOS" programs would run; but most commercial PC software used IBM BIOS extensions and would fail. Several companies offered software or hardware solutions to permit unmodified PC programs to work on the Z-100.

    The Z-100 had unusually good graphics for its era, superior to the contemporary CGA (640×200 monochrome bitmap or 320×200 4-color), IBM Monochrome Display Adapter (MDA) (80×25 text-only), and arguably even the Hercules Graphics Card (720×348 monochrome). Early versions of AutoCAD were released for the Z-100 because of these advanced graphics.

    Aftermarket vendors also released modifications to upgrade mainboard memory and permit installation of an Intel 8087 math coprocessor.

    Uses

    In 1983, Clarkson College of Technology (now Clarkson University) became the first college in the nation to give each incoming freshman a (Z-100) personal computer.

    Reception

    Jerry Pournelle in June 1983 praised the Z-100's keyboard, and wrote that it "had the best color graphics I've seen on a small machine". He reported in December 1983 that a friend who was inexperienced with electronic kits was able to assemble a H100 in a day, with only the disk controller needing soldering.

    References

    Zenith Z-100 Wikipedia
    (Text) CC BY-SA