View source for Zenith Z-89

{{Short description|Personal computer produced by Zenith Data Systems}}
{{Infobox information appliance
| name = Zenith Z-89
| title = Zenith Z-89
| aka = Heathkit H89
| logo = 
| image = ZenithZ89 delsener.jpg
| caption = Zenith Z-89 in Paris 2008
| developer = 
| manufacturer = [[Zenith Data Systems]] (ZDS)
| family = 
| type = [[Personal computer]]
| generation = 
| releasedate = {{Start date and age|1979}}
| lifespan = 
| price = Kit version with 1 floppy drive: US$1800 in 1979 (circa {{Inflation|US|1800|1979|r=-2|fmt=eq}})
| discontinued = {{End date|1985}}
| unitssold = 
| unitsshipped = 
| media = 
| os = [[Machine code monitor|ROM monitor]], [[HDOS]], [[CP/M]], [[UCSD Pascal]] (P-System Pascal), or [[MP/M]]
| power = 
| soc = 
| cpu = 2x 2.048 MHz [[Zilog Z80]] (one for the terminal)
| memory = RAM: 16 KB &ndash; 48&nbsp;KB on main board, optional 16&nbsp;KB memory card (max addressable: CP/M - 64&nbsp;KB, HDOS - 56&nbsp;KB)
| storage = 
| memory card = 
| display = 12" monochrome CRT, 80 x 25 character text
| graphics = 
| sound = Beeper
| input = 
| controllers = 
| camera = 
| touchpad = 
| connectivity = 3 serial, 1 [[Centronics]] parallel (optional), external diskette drive connector
| platform = 
| service = 
| dimensions = 
| weight = 
| topgame = 
| compatibility = 
| predecessor = 
| successor = 
| related = Heathkit H88
| website = <!--{{URL|example.org}}-->
}}
[[Image:Heathkit computer H88.JPG|thumb|250px|right|Heathkit '''H88''' computer]]
[[Image:Heathkit H89 Computer.jpg|thumb|250px|right|Heathkit '''H89''' aka Zenith '''Z-89'''.  This unit has two half-height DD diskette drives in place of the single full-height original.]]

The '''Z-89''' is a [[personal computer]] introduced in 1979 by [[Heathkit]], but produced primarily by [[Zenith Data Systems]] (ZDS) in the early 1980s. It combined an updated version of the [[Heathkit H8]] microcomputer and H19 terminal in a new case that has room for a built-in [[floppy disk]] on the right side of the display. Based on the [[Zilog Z80]] [[microprocessor]], it is capable of running [[CP/M]] as well as Heathkit's own [[HDOS]].

== Description ==
The Zenith Z-89 is based on the [[Zilog Z80]] [[microprocessor]] running at 2.048&nbsp;MHz, and supports the [[HDOS]] and [[CP/M]] operating systems. The US$2295 Z-89 is integrated in a [[computer terminal|terminal]]-like enclosure with a non-detachable keyboard, 12-inch monochrome [[Cathode ray tube|CRT]] with a 80x25 character screen, 48&nbsp;KB [[Random-access memory|RAM]], and a 5.25" [[Floppy disk|floppy disk drive]].{{r|dahmke198008}}

The keyboard is of high build quality and has an unusual number of special purpose keys: {{Key press|REPEAT}}, {{Key press|ESC}}, {{Key press|TAB}}, {{Key press|CAPS}}, {{Key press|CTRL}}, {{Key press|SCROLL}}, {{Key press|RESET}}, {{Key press|BREAK}}, {{Key press|BACK SPACE}}, {{Key press|LINE FEED}}, {{Key press|DELETE}}, and three with white, red, and blue squares. There are five function keys and a numeric keypad. The video display has reverse video and character 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 [[Benton Harbor Bus]]-compatible [[expansion card]]s. 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 [[RAM drive|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 [[Heathkit|Heath Company]], 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 supports [[Double-sided disk|double-sided]], double density, 96&nbsp;tpi drives with a capacity of 640 kB. It also came standard with 64&nbsp;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&nbsp;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 160 kB per floppy. 
* The '''H37'''/'''Z-37''' supports up to two Double-Sided, Double Density, 96&nbsp;tpi 5.25" drives and requires the soft-sectored controller. Each drive has a capacity of 640 kB. 
* The '''Z-47''' supports two 8" floppy drives and requires its own interface card. It uses standard IBM 3740 floppy disks with has a capacity of 1.2&nbsp;MB each.
* The '''Z-67''' is a 10&nbsp;MB [[Winchester drive|Winchester Drive]] plus one 8" floppy drive and also requires its own interface card.
* In France, the Heath/Zenith Data System branch connected the 10&nbsp;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]]'' described the Heath H89 as "the most professional looking" microcomputer available. Stating that it 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.<ref name="heuer198004">{{Cite magazine |last=Heuer |first=Randy |date=April 1980 |title=Heathkit WH-89 (All-in-One) Computer |url=https://archive.org/details/CreativeComputingbetterScan198004/page/n19/mode/1up |magazine=Creative Computing |pages=18–21 |volume=6 |issue=4 |access-date=2022-04-16}}</ref> ''[[BYTE]]'' wrote that the H89 "has a number of unique hardware features and the same excellent software support and documentation as the original [[Heathkit H8|H-8]] system", although recommending a second floppy drive when used with HDOS.<ref name="dahmke198008">{{cite magazine | url=https://archive.org/stream/byte-magazine-1980-08/1980_08_BYTE_05-08_The_Forth_Language#page/n47/mode/2up | title=The Heath H-89 Computer | magazine=BYTE | volume=5 | issue=8 | date=August 1980 | access-date=18 October 2013 | author=Dahmke, Mark | pages=46}}</ref>

Despite finding bugs in how the terminal interacted with [[Supercalc]], [[Jerry Pournelle]] praised the Zenith Z-19 in 1982 as "an excellent terminal in many ways—I recommend it as about as good as you can get just now".<ref name="pournelle198205">{{Cite magazine |last=Pournelle |first=Jerry |date=May 1982 |title=Supercalc, Spelling Programs, BASIC Compilers, and Home-Grown Accounting |url=https://archive.org/details/eu_BYTE-1982-05_OCR/page/n227/mode/1up?view=theater |access-date=2024-12-28 |magazine=BYTE |page=226}}</ref>

Zenith acknowledged that selling kit computers not designed to be shipped preassembled sometimes caused problems. The Z-89's successor, the [[Zenith Z-100]], was designed as a preassembled product.<ref name="mace19820412">{{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&pg=PA3 |access-date=2025-03-16 |magazine=InfoWorld |pages=1,4}}</ref>

== Summary ==
{| class=wikitable
|-
|'''Display''' || integral 12" monochrome CRT (choice of white or green), 80 × 25 characters (25th line was a special status line)
|-
|'''Storage'''  || 5.25" diskette drive (originally hard-sectored, 100&nbsp;KB)
|-
|'''Operating System''' || [[HDOS]], [[CP/M]], [[UCSD Pascal]] (P-System Pascal), or [[MP/M]] 
|}

== References ==
{{reflist}}
;Notes
#{{note|dollars}} [https://web.archive.org/web/20060717174132/http://oregonstate.edu/dept/pol_sci/fac/sahr/sahr.htm Inflation Conversion Factors for Dollars]

== External links ==
=== Reference and description ===
* [https://web.archive.org/web/20110720063204/http://www.obsoletecomputermuseum.org/zenith/ obsoletecomputermuseum.org/zenith/]
* [http://heathkit.garlanger.com/ Classic Heathkit Computers and Heathkit H89 Emulators in Javascript (online) and C++]
* [https://web.archive.org/web/20060208111428/http://www.old-computers.com/museum/computer.asp?st=1&c=135 old-computers.com]
* [https://web.archive.org/web/20070221181756/http://www.thesvd.com:80/SVD/heathkit-h89.php Connecting a virtual diskette drive to the H89] 
* [http://www.pestingers.net/pages-images/heathkit/computers/computer-history/computers-cat-history.htm Actual scanned Heathkit/Zenith Catalogs with much more information]

=== Emulators ===
* [https://github.com/mgarlanger/VirtualH89 Github project page for the Virtual H89 emulator]

[[Category:Personal computers|Zenith]]
[[Category:8-bit computers]]
[[Category:Zenith Data Systems]]
[[Category:Z80-based computers]]
[[Category:Computer-related introductions in 1979]]