Zenith Z-100

The Zenith Data Systems Z-100 is a pre-assembled version of the Heathkit H100 electronic kit,{{r|pournelle198312}} but unlike the Zenith Z-89 the Z-100 was designed first as a preassembled product.{{Cite magazine |last=Mace |first=Scott |date=1982-04-12 |title=Zenith working on 16-bit micros |url=https://books.google.com/books?id=YjAEAAAAMBAJ&lpg=PA3&pg=PA1#v=onepage&q&f=true |access-date=2025-03-16 |magazine=InfoWorld |pages=1,4}} 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.{{Cite web|url=http://www.computinghistory.org.uk/det/44090/Zenith-Z-100/|title = Zenith Z-100 - Computer - Computing History}} Both models have a built-in keyboard that was modeled after the IBM Selectric typewriter.

• Dual processors: 8085 and 8088.
• Available with CP/M and Z-DOS{{r|hardware}} (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,{{r|pournelle198306}} including Lotus 1-2-3.{{Cite magazine |last=Pournelle |first=Jerry |author-link=Jerry Pournelle |date=September 1983 |title=Eagles, Text Editors, New Compilers, and Much More |url=https://archive.org/details/byte-magazine-1983-09/page/n321 |magazine=BYTE |page=307 |access-date=2019-04-07}} 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,{{r|pournelle198306}} 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.{{citation|title=One Company's CAD Success Story |url=https://books.google.com/books?id=qS4EAAAAMBAJ&pg=PA39|publisher=InfoWorld|access-date=19 July 2014|date=3 December 1984}}

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

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.{{cite news|title=Computers to Come With Books at Drexel U.|url=https://www.nytimes.com/1982/10/28/us/computers-to-come-with-books-at-drexel-u.html|access-date=9 December 2013|newspaper=New York Times|date=October 28, 1982}}{{cite news|title=Supershorts|url=https://books.google.com/books?id=soGti0kvtgwC&q=%22clarkson+college%22+z-100+students&pg=RA1-PA97|access-date=9 November 2011|newspaper=Computer World|date=August 15, 1983}}{{cite news|title=Clarkson College to Issue Computers to Student Body|url=http://www.bitsavers.org/pdf/computerFaire/SiliconGulchGazette/32_Feb83.pdf|access-date=9 November 2011|newspaper=Silicon Gulch Gazette|date=February 1983}}

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".{{cite magazine | url=https://archive.org/details/byte-magazine-1983-06/page/n411/mode/2up | title=Zenith Z-100, Epson QX-10, Software Licensing, and the Software Piracy Problem | magazine=BYTE | date=June 1983 | access-date=10 September 2024 | author=Pournelle, Jerry | page=411}}{{r|pournelle198309}} Although forced to buy a real IBM PC because of the Z-100 and other computers' incomplete PC compatibility,{{r|pournelle198309}} 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.{{cite magazine | url=https://archive.org/details/byte-magazine-1983-12/page/n59/mode/2up | title=Buddy, Can You Spare a Door Latch? | magazine=BYTE | date=December 1983 | access-date=10 September 2024 | author=Pournelle, Jerry | page=59}} 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".{{Cite magazine |last=Skier |first=Ken |date=January 1984 |title=The Zenith Z-100 |url=https://archive.org/details/byte-magazine-1984-01/page/n269/mode/1up?view=theater |magazine=BYTE |pages=268–278 |access-date=2021-11-06}}

{{Reflist|30em}}

• [http://www.digibarn.com/collections/systems/zenith-100-original/index.html Z-100 information and pictures] from the DigiBarn Computer Museum
• [https://www.old-computers.com/museum/computer.asp?st=1&c=261 Heathkit / Zenith Z100/110/120] at old-computers.com
• [https://planemo.org/z-100/ Z-100 Software and Manual archive] from Antediluvian Designs

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Category:Z80-based home computers

Category:8086-based home computers

Category:Zenith Data Systems

Category:Computer-related introductions in 1982