The Zenith Z-89 is based on the
Zilog Z80 microprocessor running at 2.048 MHz, and supports the
HDOS and
CP/M operating systems. The US$2295 Z-89 is integrated in a
terminal-like enclosure with a non-detachable keyboard, 12-inch monochrome
CRT displaying 80x25 characters, 48 KB
RAM, and a 5.25"
floppy disk drive (originally
hard-sectored with 100 KB storage capacity). The CRT was available in white or
green phosphor versions. The computer is compatible with
Heathkit H8 software and shipped with
Benton Harbor BASIC. Compatible operating systems are HDOS, CP/M (requiring a hardware modification by Heath/Zenith to the
ROM monitor),
UCSD Pascal (P-System Pascal), and
MP/M. The keyboard keys were high quality compared to other machines at that time. The keyboard has 19 programmable keys, including several special purpose keys: , , , , , , , , , , , and three with white, red, and blue squares. There are five function keys and a numeric keypad. 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 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 can be upgraded to 4 MHz. The computer supports the
Kansas City standard for
tape storage. In 1979, prior to Zenith's purchase of
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. These systems were among the first available that supported
ANSI escape sequences (sequences similar to the
VT52 were also supported). Graphics was limited to 33 block/box drawing characters along with reverse video. The 25th line did not scroll with the others. 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, double density, 96 tpi drives with a capacity of 640 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 160 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. 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 MB each. • The
Z-67 is a 10 MB
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 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 ==