Time Sharing Limited (TSL) was the United Kingdom's first
time sharing computer services company.
1st. Generation System
Time Sharing Limited was founded in 1967 by Richard ("Dick") Evans who had been impressed by
Digital Equipment Corporation's minicomputers. It started service from a small office on Great Portland Street, London, with a dual, fault-tolerant system consisting of a front-end switch directing traffic to two units, each consisting of a PDP-7 and a
PDP-8
The PDP-8 is a 12-bit computing, 12-bit minicomputer that was produced by Digital Equipment Corporation, Digital Equipment Corporation (DEC). It was the first commercially successful minicomputer, with over 50,000 units being sold over the model's ...
. The PDP-7 interpreted messages and the PDP-8 ran the appropriate application. A
PDP-9
The PDP-9, the fourth of the five 18-bit minicomputers produced by Digital Equipment Corporation, was introduced in 1966. A total of 445 PDP-9 systems were produced, of which 40 were the compact, low-cost PDP-9/L units..
History
The 18-bit PDP ...
controlled access to persistent storage based on
NCR CRAM Memory. The system used the
TELCOMP
TELCOMP was a programming language developed at Bolt, Beranek and Newman (BBN) in about 1964 and in use until at least 1974. BBN offered TELCOMP as a paid service, with first revenue in October 1965. The service was sold to On-Line Systems, Inc. ...
interpretive language that had been developed by
Bolt, Beranek and Newman
Raytheon BBN (originally Bolt Beranek and Newman Inc.) is an American research and development company, based next to Fresh Pond in Cambridge, Massachusetts, United States.
In 1966, the Franklin Institute awarded the firm the Frank P. Brown ...
.
Customers leased a modem from the General Post Office (later
British Telecom
BT Group plc (trade name, trading as BT and formerly British Telecom) is a British Multinational corporation, multinational telecommunications holding company headquartered in London, England. It has operations in around 180 countries and is th ...
) and a Westrex
Teletype Model 33
The Teletype Model 33 is an electromechanical teleprinter designed for light-duty office use. It is less rugged and cost less than earlier Teletype machines. The Teletype Corporation introduced the Model 33 as a commercial product in 1963 after ...
from TSL. Line speeds were limited to 110 Baud (about 10 characters per second
PS. Customers were charged for each minute that they were logged onto the system. The initial persistent storage system was based on
NCR CRAM units, which used magnetic cards hanging from a digitally addressed set of rods.
Applications
TSL quickly developed a range of applications for business, scientific and engineering customers. The most highly used were the
PERT
Pert or PERT may refer to:
Ships
* - see List of United States Navy ships: P
* , a World War II corvette, originally HMS ''Nepeta''
* ''Pert'' (sidewheeler), a 19th-century steamboat that operated in British Columbia, Canada
Statistics
* PER ...
application, for critical path network planning, and an embryonic corporate modeling tool that could be regarded as a forerunner to spreadsheets. TSL soon licensed programs from other DEC customers, including the Nastran finite element modeling system and an early Database Management System called Oliver. TSL's Consultancy Division also developed applications, or modified services, for its customers. The most advanced applications used the
MACRO-10
MACRO-10 is an assembly language with extensive macro facilities for DEC's PDP-10-based Mainframe computer systems, the DECsystem-10 and the DECSYSTEM-20. MACRO-10 is implemented as a two-pass assembler.
Programming examples
A simple " Hello, ...
assembly language.
2nd. Generation System
TSL introduced its first high throughput system in early 1970, based on a
PDP-10
Digital Equipment Corporation (DEC)'s PDP-10, later marketed as the DECsystem-10, is a mainframe computer family manufactured beginning in 1966 and discontinued in 1983. 1970s models and beyond were marketed under the DECsystem-10 name, especi ...
, later known as the DECSystem-10, housed in London offices at the corner of Great Portland Street and Devonshire Street. The service eventually had two powerful systems for continuous service and a third, smaller system as a backup. Storage consisted of disk drives, tape decks and
Bryant magnetic drums for swap space. The operating system was
TOPS-10
TOPS-10 System (''Timesharing / Total Operating System-10'') is a discontinued operating system from Digital Equipment Corporation (DEC) for the PDP-10 (or DECsystem-10) mainframe computer family. Launched in 1967, TOPS-10 evolved from the earlier ...
. The new service could support batch,
remote job entry, time sharing and
real-time
Real-time or real time describes various operations in computing or other processes that must guarantee response times within a specified time (deadline), usually a relatively short time. A real-time process is generally one that happens in defined ...
loads. It was accessible via a range of terminal devices, including 30 CPS Texas Instruments
Silent 700 portable units with an acoustic modem to
Tektronix storage tubes, which ran at around 2,400 CPS.
Fortran II was added in addition to
TELCOMP III. Multiplexers were set up in Birmingham and Edinburgh to reduce line charges. Customers were charged for connect time, application usage, file storage, tape and card deck transfers and line printer output.
Customers and Acquisition
By 1973 TSL was well established, with customers that included 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. Time Sharing Limited was acquired by
ADP in 1974.
Citations
{{reflist
Defunct technology companies of the United Kingdom
British companies disestablished in 1974
British companies established in 1967