Zenith Data Systems

Zenith Data Systems (ZDS) was a division of Zenith Electronics founded in 1979 after Zenith acquired Heathkit, which had, in 1977, entered the personal computer market. Headquartered in Benton Harbor, Michigan, Zenith sold personal computers under both the Heath/Zenith and Zenith Data Systems names. Zenith was an early partner with Microsoft, licensing all Microsoft languages for the Heath/Zenith 8-bit computers. Conversely, Microsoft programmers of the early 1980s did much of their work using Zenith Z-19 and Z-29 CRT display terminals hooked to central mainframe computers. The first Heathkit H8 computer, sold in kit form, was built on an Intel 8080 processor. It ran K7 audio-tape software, punched tape software (with puncher/reader H10) and HDOS (Heath Disk Operating System) software on 5¼" hard-sectored floppy disks. The CP/M operating system was adapted to all Heath/Zenith computers, in 1979. Next, the early Heath/Zenith computers (H88/H89 and Z-89) were based on the Z80 processors and ran either HDOS or CP/M operating systems.

ZDS's first computers were preassembled versions of Heathkit computers. As subsidiary of a television company, ZDS could obtain monitors at cost. It continued selling computers in kit form—the equivalent of the ZDS Z-150 IBM PC compatible was the Heathkit H-150, for example—and opened more Heathkit Electronic Centers while also selling through Zenith dealers and seeking corporate customers. The company also continued Heath's practice of publishing unusually clear product documentation, distributing schematics, and selling the source code to HDOS and other software in printed form.

ZDS introduced the Z-100, its first computer not based on a kit design and second 16-bit product after the H11 minicomputer, in early 1982. Targeted for professionals, it had an S-100 bus, high performance color graphics, an 8-bit Z80 and an 8088 processor. It ran Z-DOS, an OEM version close to MS-DOS, but was not yet the "PC compatible" machine (in peculiar, the floppy- disks were not IBM-PC compatibles). Later machines (Z-150, Z-2xx, Z-3xx ... ) were PC compatible.