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Heathkit H11

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Heathkit H11

Heathkit H11
Type Personal Computer
Release date 1977 (1977)
Introductory price US$1295 (kit)
Media optional 8-inch floppy disks, optional paper tape
Operating system optional HT-11
CPU LSI-11 clocked at 2.5MHz
Memory 4kB base system, maximum optional 32kB RAM, 8kB ROM
Related articles PDP-11

The Heathkit H11 Computer was an early kit-format personal computer introduced in 1977. It was essentially a Digital Equipment PDP-11 in a small-form-factor case, designed by Heathkit. The H11 was one of the first 16-bit personal computers, at a list price of US$1,295 [1]


The H11 featured:[2]

  • Processor — LSI-11 (KD11-HA half-size or "double-height" card)
  • Speed — 2.5 MHz
  • ROM — 8KB (max)
  • RAM — 32KB (max)
  • Slots — 7 Q-bus slots
  • Storage — H27 8-inch floppy drive (2 256k 8-inch single sided drives) or paper tape
  • I/O — serial (RS-232) or parallel ports
  • Operating system — HT-11 (a simplified version of RT-11)
  • Instruction set — PDP-11/40 instruction set which included over 400 instructions
  • Languages — BASIC, Focal and others

Initial memory limitations restricted the selection of software the system could handle, but the system could be expanded to 32KB of RAM. Many PDP-11 operating systems and programs ran without trouble. The system would also work with most DEC PDP-11 equipment, including many Q-bus compatible peripherals.

See also


  1. ^ Heathkit 1978 catalog pages retrieved 2011 July 11
  2. ^ 1977 advertising material from Heathkit of Benton Harbor, Michigan.

External links

  • Heathkit H-11 Computer, Heathkit Computer Advertisements, Decode Systems
  • Computer Museum illustration of fully expanded H11 with the Heath/Zenith label.
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