website/content/museum/ibm-an-fsq-7.md

---
title: IBM AN/FSQ-7
categories:
- Computers
types:
- Professional Computer
origins:
- U.S.A.
years:
- '1958'
cpus:
- '55'
params:
  name: AN/FSQ-7
  image: /media/museum/photos/ibm_anfsq7_part_s1.jpg
  company: /companies/ibm
  company_name: IBM
  specs:
  - label: NAME
    value: AN/FSQ-7
  - label: MANUFACTURER
    value: IBM
  - label: TYPE
    value: Professional Computer
  - label: ORIGIN
    value: U.S.A.
  - label: YEAR
    value: '1958'
  - label: END OF PRODUCTION
    value: '1963'
  - label: BUILT IN LANGUAGE
    value: None
  - label: KEYBOARD
    value: IBM consoles
  - label: CPU
    value: 55,000 vacuum tubes in each unit
  - label: SPEED
    value: 75 KIPS (KiloInstructions Per Second)
  - label: CO-PROCESSOR
    value: None
  - label: RAM
    value: Core 8892-word
  - label: ROM
    value: Unknown
  - label: TEXT MODES
    value: None
  - label: GRAPHIC MODES
    value: 256 x 256
  - label: COLORS
    value: Monochrome
  - label: SOUND
    value: Speaker (see the ''Read more'' page)
  - label: SIZE / WEIGHT
    value: 2000 square meters / 275 tons
  - label: I/O PORTS
    value: Tape, punched cards, modem
  - label: BUILT IN MEDIA
    value: Tape
  - label: OS
    value: None
  - label: POWER SUPPLY
    value: 3 MW
  - label: PRICE
    value: $238 million, printer around $200,000 to $250,000
  tabs:
  - photos
  - links
  forum_thread: 1023
  photos:
  - title: SYSTEM DIAGRAM
    subtitle: ''
    text: |-
      An AN/FSQ-7 installed in a 4-story SAGE Direction Center building.

      Photo from **[Mitre](http://www.mitre.org/about/photo_archives/sage_photo.html)**
    image: /media/museum/photos/ibm_anfsq7_diagram_s1.jpg
  links:
  - title: Mitre Corp. museum
    url: http://www.mitre.org/about/photo_archives/sage_photo.html
    text: SAGE photo archives
  - title: Radomes, Inc. museum
    url: http://www.radomes.org/museum/equip/fsq-7.html
    text: More information and pictures about the AN/FSQ-7
  - title: Reminiscences of Jack Gilmore
    url: http://ed-thelen.org/comp-hist/TheCompMusRep/TCMR-V02.html#Reminiscences
    text: ''
  - title: SMECC Museum
    url: http://www.smecc.org/sage_a_n_fsq-7.htm
    text: More pictures of the SAGE system
  oc_id: 1050
  source:
    url: https://web.archive.org/web/20230603204628/http://www.old-computers.com/museum/computer.asp?c=1050
    date: '2023-06-03'
---

The AN/FSQ-7 was by far the largest computer ever built, and is expected to hold that record. It consisted of two complete [Whirlwind II](/museum/mit-whirlwind/) computers installed in a 4-story building (See the impressive diagram in the 'More Pictures' section).

Each AN/FSQ supported more than 100 users. IBM had about 60 employees at each site for round-the-clock maintenance.\
Keeping one unit operating and one on hot standby (to allow for switchover when vacuum tubes failed) resulted in better than 99% uptime. The roles of the two units were reversed at regular intervals, allowing diagnostics and maintenance to be carried out on the standby unit.

There were usually several hundred tube failures each day, replaced by workers racing up and down the tube racks with shopping carts full of replacements. Automated tests run by the computer itself would cycle the voltage to the tube racks down and back up to induce marginal tubes to fail early, so that the computer would normally run correctly for the rest of the day. Without this process, the MTBF would have been a few minutes.

By the time SAGE was deployed (22 or 23 stations in the period 1959-1963; sources disagree) it was nearly obsolete, since it was designed to detect bombers, not the new ICBMs. Nevertheless it was operational until 1979, when the ROCC (Regional Operations Control Centers) system took over, using much higher-speed computers. One SAGE station continued operating until 1983. This last unit was donated to the Boston Computing Museum, since relocated to Moffett Field in Mountain View, California. The museum also has a tube panel from the Whirlwind I. Whirlwind II consoles turned up in the TV series *Battlestar Galactica*.\
In spite of its limited military value, the SAGE system served as an excellent prototype for an air-traffic control system. The FAA operated its own AN/FSQ-7 systems for many years after SAGE was shut down. IBM's experience with these systems had a great deal to do with its later success in computer systems, and its dominance of the market for large computers. The IBM 7090 was essentially a solid-state version of the AN/FSQ-7/8. (The 7090 has its own rich history, including hosting the first-ever multiuser APL system.)

• First CRT-based real-time user interface,\
• First use of light gun to pick an item on the screen,\
• First wide-area modem communications (1300 bps),\
• First hot standby system for maximum uptime,\
• First ground control of interceptor aircraft,\
• The first in line microfilm fast processed 35 mm projection displays, preceding printer/plotters. A screen capture could be displayed within 30 seconds, • First two-pass assembler, permitting symbolic addresses.

Thanks to **Edward Cherlin**, [Simputer Evangelist](http://www.ryze.com/go/Cherlin), for all this information.

The photo (from [Mitre](http://www.mitre.org/about/photo_archives/sage_photo.html)) shows the rear panel wiring of FSQ-7 arithmetic element frame.

We need more info about this computer ! If you designed, used, or have more info about this system, please send us pictures or anything you might find useful.