Time Sharing Limited
| Company type | Private |
|---|---|
| Industry | Computer services, Time sharing |
| Founded | 1967 |
| Founder | Richard ("Dick") Evans |
| Fate | Acquired by ADP in 1974 |
| Headquarters | London , United Kingdom |
| Products | Time sharing computer services, business/scientific/engineering software, consultancy services |
Time Sharing Limited (TSL) holds the distinction of being the United Kingdom's pioneering provider of time sharing computer services.
1st. Generation System
Established in 1967 by Richard ("Dick") Evans and motivated by the minicomputers from Digital Equipment Corporation, TSL commenced operations from a modest office in London. The initial setup featured a dual fault-tolerant architecture, consisting of a front-end switch that routed communications to two separate units. Each unit included a PDP-7 for message interpretation and a PDP-8 dedicated to running applications. A PDP-9 was responsible for managing access to persistent storage, which was based on NCR CRAM Memory technology. The system operated using the TELCOMP interpretive language created by Bolt, Beranek and Newman.
Clients obtained modems through the General Post Office (which later became British Telecom) and leased Westrex Teletype Model 33 terminals directly from TSL. Connection speeds were capped at 110 Baud (approximately 10 characters per second). Billing was calculated according to the duration of connections. The initial data storage solution employed NCR CRAM magnetic card units.
Applications
TSL quickly expanded its portfolio of business, scientific, and engineering software solutions. Among its notable products were a PERT tool designed for critical path analysis and an early corporate modeling system that served as a forerunner to modern spreadsheet applications. Additionally, TSL licensed software such as the Nastran finite element analysis package and the Oliver Database Management System from other DEC users. Its Consultancy Division also provided tailored application development services to meet specific client needs. More sophisticated software utilized the MACRO-10 assembly language.
2nd. Generation System
In early 1970, TSL introduced a high-capacity service built around the PDP-10, later branded as DECSystem-10, operating from offices located on Great Portland Street and Devonshire Street in London. The infrastructure comprised two main systems designed for uninterrupted operation alongside a smaller backup unit. Storage solutions included disk drives, tape decks, and Bryant magnetic drums used as swap space. The operating system deployed was TOPS-10. This platform supported multiple computing modes such as batch processing, remote job entry, time sharing, and real-time applications. Access was facilitated via various terminals, including 30 CPS Texas Instruments Silent 700 portable devices equipped with acoustic modems and high-speed Tektronix storage tubes capable of approximately 2,400 CPS. Programming languages available expanded to include Fortran II, COBOL, and an enhanced version of TELCOMP known as TELCOMP III. Multiplexers located in Birmingham and Edinburgh helped reduce line costs. Clients were charged based on connection duration, application usage, file storage, data transfer volumes, and output from line printers.
Customers and Acquisition
By 1973, TSL had secured a diverse client portfolio featuring organizations such as the Greater London Council, Foster Wheeler, Baring Bros., British Shipbuilding Research Association, Mather & Platt, London Weekend Television, the Metropolitan Police, Unilever, Lloyds, and the Royal Signals. In 1974, Time Sharing Limited was acquired by ADP.