Zenith ZF 158-42

Zenith ZF 158-42

[Vin180]

The Zenith ZF 158-42 was a notable early IBM PC-compatible portable computer from the mid-1980s, recognized for its robust build and business-oriented features, including an 8 MHz 8088 CPU, detachable keyboard, and dual 360K 5.25-inch floppy drives, making it suitable for extended work sessions and early mobile computing needs. Zenith Data System had a reputation for producing reliable, competitively priced PC clones that were widely adopted in government, education, and corporate environments, contributing to Zenith’s status as one of the top PC clone manufacturers of its era.

• Manufacturer: Zenith Data Systems Corporation
• Type: Personal computer
• Release Date: 1984
• Cost at release: ~$7,500 (adjusted for inflation)
• MIPS: ~0.3 (300 KIPS)

Hardware Specifications

• CPU: Intel 8088​ 8 MHz
• Memory: 256 KB RAM (expandable up to 640 KB)​​
• Storage: Dual 5.25-inch 360 KB floppy disk drives (720 KB total storage)​​
• RGB and composite video outputs​
• Four ISA expansion slots​
• Two RS-232 serial ports and one parallel port​
• Detachable keyboard​
• Optional hard drive (up to 10.6 MB) and second floppy drive​

Operating System & Programming Languages 

• Operating System: Zenith Data Systems’ version of MS-DOS, called ZDOS
• Supported Languages:
  • Microsoft BASIC (often included with MS-DOS)
  • GW-BASIC
  • Turbo Pascal
  • Microsoft C and other early C compilers
  • Assembly language for the Intel 8088 processor

Notables

• The Zenith ZF 158-42, produced by Zenith Data Systems (post-Heathkit acquisition), was an early 1985 IBM PC XT clone with a unique “luggable” portable design featuring detachable keyboard and pop-up floppy drives, epitomizing the transition from desktops to transportables.
• It benefited from Zenith’s massive government contracts, including IRS and DoD deals that made ZDS the top US portable vendor by 1988, shipping over 433,000 units amid fierce clone competition.
• Notable quirks include the Ctrl+Alt+Ins “PAM-8” ROM monitor (from Heathkit roots) for diagnostics and a passive backplane cramming all logic onto one card, rare for XT clones

Donated by: Carleton University’s ITS