ECHO IV

James Sutherland worked as an engineer for the American company Westinghouse Electric, designing fossil and nuclear power plant control systems. In 1959 the company built a computer called PRODAC IV (he was the designer of the arithmetic logic unit), using destructive-readout core memory and NOR logic.

When PRODAC IV was replaced by a UNIVAC design, some of the Westinghouse controller hardware was declared surplus in 1965.[3][2] Sutherland took up surplus boards and memory to build a home computer, ECHO IV (the "IV" in ECHO IV came from the PRODAC IV). It was made public for the first time in 1966.[4][2]

The computer was working in the Sutherland's house until 1976, and was donated to the Computer Museum in Boston in 1984.[2][5][6]

• Processor
  • Transistorized[7] (2N404), with RTL NOR logic elements[8][9]
  • 120 circuit modules[5][10]
  • 18 commands
  • 4 registers
• Add time: 216 μs
• Frequency: 160 kHz[11][5][10]
• Main memory:
  • 8,192 15-bit words,[12][7][10] magnetic core[5]
• Input/Output:
  • paper tape reader and punch
  • keyboard made from parts of IBM Selectric typewriter
  • Kleinschmidt teleprinter
• Physical specifications:
  • Four large wooden cabinets,[13] each with approximate dimension of:
    • Width: 4 feet
    • Height: 6 feet
    • Depth: 2 feet[3]
  • Weight: about 800 pounds (360 kg)[13]

• Accounting
• Household inventory
• Calendar
• Manage all digital clocks through the house
• Real-time clock with delay of 1 second
• Air conditioning management
• TV and television antenna management; on school nights children were required to answer questions if they wanted to watch television
• Meteorological program for reading and storing data from a meteorological station that was connected to ECHO IV and weather forecast[14]

• Cortesi, Dave (Sep 2015). "The First Home Computer" (PDF). Volunteer Information Exchange. 5 (8): 2–3.
• Infield, Glenn (April 1968). "Science and inventions: A Computer in the Basement?". Popular Mechanics. 129 (4): 77–79, 209, 229.
• Tomayko, James E., ed. (1994). "Anecdotes: Electronic Computer for Home Operation (ECHO): The First Home Computer". IEEE Annals of the History of Computing. 16 (3): 59–61. doi:10.1109/mahc.1994.10011. ISSN 1058-6180.

• ECHO IV photos with description: "ECHO IV article - David & Marian Cortesi". cortesi.smugmug.com.
• Spicer, Dag (31 May 2016). "The ECHO IV Home Computer: 50 Years Later | @CHM Blog | Computer History Museum". www.computerhistory.org.
• Computer History Museum (January 13, 2015), Living with ECHO-IV (video) (published 21 Feb 2018), Timecodes: 0:00 - What was "Advanced Technology" in 1965?, 13:55 - Was ECHO IV a Real Computer?, 23:46 - What Tasks did ECHO IV Perform?, 47:23 - Magazine and Newspaper Articles, 48:27 - Where is ECHO IV Now?, retrieved 2019-02-09
• "Amateur Construction of Computers: Building your own computer - Part 2: Completed Computers". Computers and Automation (1): 20–21. Jan 1972.