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The Z-89 is a
personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...
produced by
Zenith Data Systems Zenith Data Systems (ZDS) was a division of Zenith Electronics founded in 1979 after Zenith acquired the Heath Company, which had entered the personal computer market in 1977. Headquartered in Benton Harbor, Michigan, Zenith sold personal compu ...
(ZDS) in the early 1980s.


Description

The Zenith Z-89 is based on the
Zilog Z80 The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples wer ...
microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...
running at 2.048 MHz, and supports the
HDOS HDOS is an early microcomputer operating system, originally written for the Heathkit H8 computer system and later also available for the Heathkit H89 and Zenith Z-89 computers. The author was Heath Company employee Gordon Letwin, who later was ...
and
CP/M CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...
operating systems. The US$2295 Z-89 is integrated in a
terminal Terminal may refer to: Computing Hardware * Terminal (electronics), a device for joining electrical circuits together * Terminal (telecommunication), a device communicating over a line * Computer terminal, a set of primary input and output dev ...
-like enclosure with a non-detachable keyboard, 12-inch monochrome CRT with a 80x25 screen, 48 KB RAM, and a 5.25" floppy disk drive. The keyboard is of high build quality and has an unusual number of special purpose keys: REPEAT, ESC, TAB, CAPS, CTRL, SCROLL, RESET, BREAK, BACK SPACE, LINE FEED, DELETE, REPEAT, and two with red and blue squares. There are five function keys and a numeric keypad. The video display has reverse video and block graphics are available. The computer has two small card cages inside the cabinet on either side of the CRT, each of which accept up to three proprietary circuit cards. Upgrade cards available for this included disk controller cards (see below), a 16 KB RAM card that upgrades the standard 48 KB RAM to 64 KB, a RAM memory card accessible as a ramdrive using a special driver (above the Z80's 64 KB memory limit) and a multi-serial card providing extra RS-232 ports. The 2 MHz Z80 could be upgraded to 4 MHz. In 1979, prior to Zenith's purchase of
Heath Company Heathkit is the brand name of kits and other electronic products produced and marketed by the Heath Company. The products over the decades have included electronic test equipment, high fidelity home audio equipment, television receivers, amateu ...
, Heathkit designed and marketed this computer in kit form as the Heath H89, assembled as the WH89, and without the floppy but with a cassette interface card as the H88. (Prior to the Zenith purchase, the Heathkit model numbers did not include the dash). Heath/Zenith also made a serial terminal, the H19/Z-19, based on the same enclosure (with a blank cover over the diskette drive cut-out) and terminal controller. The company offered an upgrade kit to convert the terminal into a full H89/Z-89 computer. Another configuration, the Z-90, changes the floppy drive controller from the hard-sectored controller (max 100 kB) to a soft-sectored controller that supported double-sided, double density, 96 tpi drives with a capacity of 800 kB. It also came standard with 64 KB of RAM. There were several external drive systems available for the H89/Z-89. * The H77/Z-77 and H87/Z-87 supports up to two additional Single-Sided, Single Density, 48 tpi 5.25" drives. When connected to the standard hard-sectored controller, it stores 100 kB per floppy. By connecting it to a soft-sectored controller, it stores 200 kB per floppy. * The H37/Z-37 supports up to two Double-Sided, Double Density, 96 tpi 5.25" drives and requires the soft-sectored controller. The drive has a capacity of 800 kB. * The Z-47 supports two 8" floppy drives and requires its own controller. It uses standard IBM 3740 floppy disks with has a capacity of 1.2 MB each. * The Z-67 is a 10 MB
Winchester Drive IBM manufactured magnetic disk storage devices from 1956 to 2003, when it sold its hard disk drive business to Hitachi. Both the hard disk drive (HDD) and floppy disk drive (FDD) were invented by IBM and as such IBM's employees were responsible fo ...
plus one 8" floppy drive and also requires its own controller. * In France, the Heath/Zenith Data System branch connected the 10 MB removable cartridge hard disk, manufactured by Bull in Belfort A maximum of two disk controller cards can be installed in a standard system.


Reception

''
Creative Computing ''Creative Computing'' was one of the earliest magazines covering the microcomputer revolution. Published from October 1974 until December 1985, the magazine covered the spectrum of hobbyist/home/personal computing in a more accessible format th ...
'' described the Heath H89 as "the most professional looking" microcomputer available. Stating that the computer was "one of the finest" available for less than $3000, the magazine predicted that it "can have a major impact on the small computer market" if good software became available for it. ''
BYTE The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...
'' wrote that the H89 "has a number of unique hardware features and the same excellent software support and documentation as the original H-8 system".


Summary


References

;Notes #{{note, dollars}
Inflation Conversion Factors for Dollars


External links


Reference and description


obsoletecomputermuseum.org/zenith/

Classic Heathkit Computers and Heathkit H89 Emulators in Javascript (online) and C++

old-computers.com

Connecting a virtual diskette drive to the H89



Emulators


Github project page for the Virtual H89 emulator
Zenith The zenith (, ) is an imaginary point directly "above" a particular location, on the celestial sphere. "Above" means in the vertical direction (plumb line) opposite to the gravity direction at that location (nadir). The zenith is the "highest" ...
8-bit computers Heathkit computers Z80-based computers