Zenith Z89
Encyclopedia
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
produced by Zenith Data Systems
Zenith Data Systems
Zenith Data Systems was a division of Zenith 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...
(ZDS) in the early 1980s. It was based on the Zilog Z80
Zilog Z80
The Zilog Z80 is an 8-bit microprocessor designed by Zilog and sold from July 1976 onwards. It was widely used both in desktop and embedded computer designs as well as for military purposes...
microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
and ran the HDOS
HDOS
HDOS is an early microcomputer operating system, originally written for the Heathkit H8 computer system and later also available for the Heath H89 and Zenith Z-89 computers...
and CP/M
CP/M
CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...
operating systems. The Zenith Z-89 was integrated in a terminal
Computer terminal
A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system...
-like enclosure with a non-detachable keyboard, 12-inch monochrome CRT (standard white, optional non-glare green or amber screen), hard-sectored controller, and a 5.25" diskette drive.
In 1979, prior to Zenith's purchase of Heath Company, Heathkit had originally 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. (Note: Prior to the Zenith purchase, the Heathkit model numbers did not include the - 'dash').
Heath/Zenith also made a serial terminal, the H/Z-19, based on the same enclosure (with a blank cover over the diskette drive cut-out) and terminal controller. They even offered an upgrade kit to convert the terminal into a full H/Z-89 computer.
Another configuration, the Z-90, changed the floppy drive controller from the hard-sectored controller (max 100 KB) to a soft-sectored controller that supported double-sided
Double-sided disk
In computer science, a double-sided disk is a disk of which both sides are used to store data.Early floppy disks only used one surface for recording. The term "single sided disk" was not common until the introduction of double-sided disks, which offered double the capacity in the same physical size...
, 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 H/Z-89.
- The H/Z-77 and H/Z-87 supported up to two additional Single-Sided, Single Density, 48 tpi 5.25" drives. When connected to the standard hard-sectored controller, it could store 100 KB each. By connecting it to a soft-sectored controller, they could store 200 KB.
- The H/Z-37 supported up to two Double-Sided, Double Density, 96 tpi 5.25" drives and required the soft-sectored controller. These drives had a capacity of 800 KB each.
- The Z-47 supported two 8" floppy drives and required its own controller. These used the standard IBM 3740 floppy disks and had a capacity of 1.2 MB each.
- The Z-67 was a 10 MB Winchester Drive plus one 8" floppy drive and also required its own controller.
- In France, the Heath/Zenith Data System branch connected the 10MB removable cartridge hard disk, manufactured by Bull in Belfort
A maximum of two disk controller cards could be installed in a standard system.
Summary
| Year | 1979 – 1985 |
| CPU | Two Z80, 2.048 MHz (one for terminal) |
| RAM | 16 KB – 48 KB on main board, optional 16 KB memory card (max addressable: CP/M - 64 KB, HDOS - 56 KB) |
| Display | integral 12" monochrome CRT (choice of white, amber, or green), 80 × 25 characters (25th line was a special status line) |
| Storage | 5.25" diskette drive (originally hard-sectored, 100 KB) |
| Interfaces | 3 serial, 1 Centronics Centronics Centronics Data Computer Corporation was a pioneering American manufacturer of computer printers, now remembered primarily for the parallel interface that bears its name.-The beginning:Centronics began as a division of Wang Laboratories... parallel (optional), external diskette drive connector |
| Operating System | HDOS HDOS HDOS is an early microcomputer operating system, originally written for the Heathkit H8 computer system and later also available for the Heath H89 and Zenith Z-89 computers... , CP/M CP/M CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc... , UCSD Pascal UCSD Pascal UCSD Pascal was a Pascal programming language system that ran on the UCSD p-System, a portable, highly machine-independent operating system. UCSD Pascal was first released in 1978... (P-System Pascal), or MP/M MP/M MP/M was a multi-user version of the CP/M operating system, created by Digital Research developer Tom Rolander in 1979. It allowed multiple users to connect to a single computer, each using a separate terminal.... |
| Price | Kit version with 1 floppy drive: $1,800 in 1979 = approx. $4,800 in 2005 |
External links
- http://www.zenithdatasystems.de/z89.htm
- http://www.yesterpc.org/
- http://www.obsoletecomputermuseum.org/zenith/
- http://heathkit.garlanger.com/
- http://www.old-computers.com/museum/computer.asp?st=1&c=135
- Connecting a virtual diskette drive to the H89
- Actual scanned Heathkit/Zenith Catalogs with much more information