Heathkit H11

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Heathkit H11
Manufacturer Heathkit
Type Personal Computer
Release date 1978 (1978)
Introductory price US$1295 (equivalent to $4,682 in 2015)[1] (kit)[2]
Discontinued 1982 (1982)[3]
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 1978. 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,[2] but was too expensive for most Heathkit customers and was discontinued in 1982.[3]


The H11 featured:[4]

  • 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[citation needed]
  • 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[edit]


  1. ^ Consumer Price Index (estimate) 1800–2014. Federal Reserve Bank of Minneapolis. Retrieved February 27, 2014.
  2. ^ a b Heathkit 1978 catalog pages retrieved 2011 July 11
  3. ^ a b Wise, Deborah (1982-09-13). "Heath joins Zenith to attract hobbyists, businesses". InfoWorld. p. 19. Retrieved 8 January 2015. 
  4. ^ 1977 advertising material from Heathkit of Benton Harbor, Michigan.

External links[edit]