Wikipedia

Zenith Z-100

(Redirected from Heathkit H100)

The Z-100 computer is a personal computer made by Zenith Data Systems (ZDS). It was a competitor to the IBM PC.

Zenith Z-100
ManufacturerZenith Data Systems
Typepersonal computer
Release dateJune 1982; 42 years ago (1982-06)
Operating systemAvailable with CP/M-80, CP/M-86 and Z-DOS (non-IBM compatible MS-DOS variant)[1]
CPUDual processors: 8085 and 8088[1]
MemoryBase 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).
StorageTwo 320 KB 40-track double-sided 5.25-inch Floppy disk drives. Socket enabled direct plug-in of external 8-inch floppies.
Display25 lines × 80 characters[1]
Graphics640×225 bitmap display. 8-color (low-profile model), or monochrome upgradable to 8-level greyscale (all-in-one).[1]
Input2× serial ports (2661 UART), one Centronics printer port (discrete TTL chips), light pen port
Power300 watts[1]

Design

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The Zenith Data Systems Z-100 is a pre-assembled version of the Heathkit H100 electronic kit.[2] In the same family, the Z-120 is an all-in-one model with self-contained monitor, and the Z-110 (called the low profile model) is similar in size to the cabinet of an IBM PC.[3] Both models have a built-in keyboard that was modeled after the IBM Selectric typewriter.[3]

  • 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.
  • Two serial ports (2661 UART), one Centronics printer port (discrete TTL chips), light pen port.
  • 640×225 bitmap display, with eight colors (low-profile model), or monochrome upgradable to eight 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 is partially compatible with the IBM PC, using standard floppy drives. It runs a non-IBM version of MS-DOS, so generic MS-DOS programs run, but most commercial PC software uses IBM BIOS extensions and do not run,[4] including Lotus 1-2-3.[5] Several companies offered software or hardware solutions to permit unmodified PC programs to work on the Z-100.

The Z-100 has unusually good graphics for its era,[4] superior to the contemporary CGA (640×200 monochrome bitmap or 320×200 four-color), IBM Monochrome Display Adapter (MDA) (80×25 monochrome text-only), and with eight colors or grayscales available at a lower resolution than the Hercules Graphics Card (720×348 monochrome). Early versions of AutoCAD were released for the Z-100 because of these advanced graphics.[6]

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

Uses

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In 1983, Clarkson College of Technology (now Clarkson University) became the first college in the nation to give each incoming freshman a personal computer. The model issued to them was the Z-100.[7][8][9]

In 1986, the US Air Force awarded Zenith Data Systems a $242 million ($571 million in 2023) contract for 90,000 Z-100 desktop computers.[10]

Reception

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Jerry Pournelle in 1983 praised the Z-100's keyboard, and wrote that it "had the best color graphics I've seen on a small machine".[4][5] Although forced to buy a real IBM PC because of the Z-100 and other computers' incomplete PC compatibility,[5] he reported in December 1983 that a friend who was inexperienced with electronic kits was able to assemble a Z-100 in a day, with only the disk controller needing soldering.[2] Ken Skier praised the computer's reliability in the magazine in January 1984 after using the computer for more than 40 hours a week for eight months. While criticizing its inability to read other disk formats, he approved of Zenith's technical support, documentation, and keyboard and graphics. Skier concluded that those who "want a well-designed, well-built, well-documented system that runs the best of 8-bit and 16-bit worlds" should "consider the Zenith Z-100".[11]

References

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  1. ^ a b c d e Zenith challenges IBM's share of micro market, By Paul Freiberger, Page 35, InfoWorld, 13 September 1982
  2. ^ a b Pournelle, Jerry (December 1983). "Buddy, Can You Spare a Door Latch?". BYTE. p. 59. Retrieved 10 September 2024.
  3. ^ a b "Zenith Z-100 - Computer - Computing History".
  4. ^ a b c Pournelle, Jerry (June 1983). "Zenith Z-100, Epson QX-10, Software Licensing, and the Software Piracy Problem". BYTE. p. 411. Retrieved 10 September 2024.
  5. ^ a b c Pournelle, Jerry (September 1983). "Eagles, Text Editors, New Compilers, and Much More". BYTE. p. 307. Retrieved 2019-04-07.
  6. ^ One Company's CAD Success Story, InfoWorld, 3 December 1984, retrieved 19 July 2014
  7. ^ "Computers to Come With Books at Drexel U." New York Times. October 28, 1982. Retrieved 9 December 2013.
  8. ^ "Supershorts". Computer World. August 15, 1983. Retrieved 9 November 2011.
  9. ^ "Clarkson College to Issue Computers to Student Body" (PDF). Silicon Gulch Gazette. February 1983. Retrieved 9 November 2011.
  10. ^ "Military Picks Zenith Computeres". Retrieved 24 December 2021.
  11. ^ Skier, Ken (January 1984). "The Zenith Z-100". BYTE. pp. 268–278. Retrieved 2021-11-06.
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