International Computers and Tabulators
| Company type | Public company |
|---|---|
| Industry | Computer manufacturing |
| Predecessor | British Tabulating Machine Company, Powers-Samas |
| Founded | 1959 |
| Defunct | 1968 |
| Fate | Merged into International Computers Limited (ICL) |
| Headquarters | United Kingdom |
| Products | Computers including ICT 1101, ICT 1201, ICT 1300 series, ICT 1400, ICT 1500 series, ICT 1900 series |
International Computers and Tabulators (ICT) was a UK-based computer manufacturing company established in 1959 through the consolidation of the British Tabulating Machine Company (BTM) and Powers-Samas. In 1963, ICT expanded by acquiring the business computing units of Ferranti. The company distributed its computer systems internationally and, in 1968, became part of International Computers Limited (ICL).
Products
The ICT 1101 was initially developed as the EMIDEC 1100 prior to ICT’s acquisition of the EMI Computing Services Division.
The ICT 1201 employed thermionic valve components and utilized drum memory technology. It processed data from 80-column punched cards and produced output on cards and printers. Originally produced under BTM as the HEC4, this model featured a drum memory capacity of 1K words, each 40 bits in length. Its machine code instructions were arranged to align with the drum’s rotation, optimizing execution efficiency.
Models such as the ICT 1301 and its smaller counterpart, the ICT 1300, incorporated germanium transistor technology alongside core memory, supported by magnetic drum or tape storage for backup. Their input/output systems handled standard 80-column punched cards, with optional support for 160-column cards and paper tape. Delivered first in 1962 to the University of London, these machines included dedicated hardware for calculations using British currency (£sd) and operated with a decimal-only instruction set to streamline programming. The processor clock speed was 1 MHz. The University of London’s original machine was preserved as of 2006.
The ICT 1302 built upon the capabilities of the 1300/1301 series by introducing multiprogramming, enabling concurrent execution of three user programs alongside the Executive operating system. It also implemented the 'Standard Interface', which allowed versatile peripheral connections and was later adopted by the subsequent 1900 series.
The ICT 1400 represented an early-generation thermionic valve computer; however, it failed to secure any sales due to rapid advancements in transistor technology by 1959.
The ICT 1500 series was produced under license from RCA Corporation, based on the RCA 301 design. This series was also marketed in Europe by Siemens and Bull under the name Gamma 30. It utilized a six-bit byte structure and offered core memory capacities ranging between 10,000 and 40,000 bytes.
Following the acquisition of Ferranti’s computing assets, ICT introduced the ICT 1900 series, which incorporated technology derived from Canada’s Ferranti-Packard 6000 system. Adapted with the 'Standard Interface' for peripheral compatibility, this line debuted with the ICT 1904 model and expanded into a family of interoperable systems.
In 1968, ICT merged with English Electric Computers, itself a product of prior consolidations including English Electric Leo Marconi (EELM) and Elliott Automation, resulting in the formation of International Computers Limited (ICL). English Electric Computers was developing mainframe systems compatible with IBM System/360 architecture based on RCA’s Spectra 70 series, marketed as ICL System-4. Both the ICT 1900 range and System-4 models were eventually supplanted by the introduction of the ICL 2900 Series in 1974.
External links
- Oral history interview with Arthur L. C. Humphreys (1981), Charles Babbage Institute, University of Minnesota. Humphreys, former managing director of ICL, recounts the British computing industry’s evolution, including the formation of International Computers and Tabulators (ICT) from BTM and Powers-Samas in 1959, and ICT’s merger with English Electric Computers to create ICL in 1968.
- Boards from the ICT 1301 – archived November 2006
- ICT 1301 Resurrection Project – The National Museum of Computing
- Two articles on the HEC4 at Morgan Crucible Co – archived April 2014
References
- Articles with short description
- Obsolete computer firms in the United Kingdom
- International Computers Limited
- Outdated computer hardware manufacturers
- Former computer systems manufacturers
- No longer operating manufacturing firms in the United Kingdom
- Past defence industry companies in the United Kingdom
- Computer enterprises founded in 1959
- Electronics businesses founded in 1959
- Computer firms closed in 1968
- Electronics companies closed in 1968
- 1959 establishments in England
- 1968 closures in England
- British enterprises founded in 1959
- British enterprises closed in 1968
- British companies disestablished in 1968