Z-100 (computer)

The Z-100 computer was an early microcomputer made by Zenith Data Systems (ZDS). It was a pre-assembled version of the Heathkit (recently purchased by Zenith Electronics to become ZDS) H-100, which left the final component assembly to early computer hobbyists.

Z-100 Computers were early personal computer (PC) era alternatives to the hardware system that won the marketing shares war in the early to mid 1980s, the IBM PC/XT/AT succession or family of computers. Configured as a family (Z-120 was an all in one model, with self-contained monitor), the Z-110 (called the low profile model) was similar in size to the cabinet of an IBM PC, XT, or AT, but a bit shorter, and configured with a raised cabinet molding on the top surface within which one placed one's display monitor, designed to keep it from sliding off to either side or back. Both models had a built in keyboard that was tactilely and in appearance modeled on an IBM Selectric typewriter, the premier office machine of the day. The keyboard had a wonderful "feel" and "stroke action" that Byte Magazine columnist and fiction author Jerry Pournelle raved about in several columns.

* Dual processors: 8085 and 8088
* Available with CP/M and Z-DOS (non-IBM compatible MS-DOS variant)
* Five S-100 expansion slots
* Two 320KB 40-track double-sided 5.25-inch Floppy disk drives. Socket enabled direct plug-in of external 8-inch floppies.
* 2x serial ports (2661 UART), one Centronics printer port (discrete TTL chips), light pen port
* 640x225 bitmap display. 8 colors (low-profile model), or monochrome upgradable to 8 greyscales (all-in-one).
* Base 128k RAM, expandable to 192K on-board, to 768K with S-100 cards. (Video RAM was paged into the 64K block above 768K).

The Z-100 was a "near-compatible" system to the IBM PC, using standard floppy drives. It ran a non-IBM version of MS-DOS, so "generic MS-DOS" programs would run; but most commercial PC software used IBM BIOS extensions and would fail. Several companies offered software or hardware solutions to permit unmodified PC programs to work on the Z-100.

The Z-100 had superior graphics to the contemporary CGA (640x200 monochrome bitmap or 320x200 4-color), IBM Monochrome Display Adapter (80x25 text-only), and even the Hercules Graphics Card (640x225 monochrome). Early versions of AutoCAD were released for the Z-100 because of these advanced graphics.

Aftermarket vendors also released modifications to upgrade mainboard memory and permit installation of an Intel 8087 math coprocessor.

In 1983, Clarkson College (now University) required all incoming freshmen to purchase a Z-100 computer as part of their entry requirement, making it one of the first institutions to mandate computers for its students.

External links

* [http://www.digibarn.com/collections/systems/zenith-100-original/index.html Z-100 information and pictures] from the DigiBarn Computer Museum