HISTORY

Occam is an ideal introduction to a number of key methodologies in modern computer science. Occam programs can provide a degree of security unknown in conventional programming languages such as C, FORTRAN or Pascal. occam simplifies the task of program verification, by allowing application of mathematical proof techniques to prove the correctness of programs. Transformations, which convert a process from one form to a directly equivalent form, can be applied to the source of an occam program to improve its efficiency in any particular environment. occam makes an ideal language for specification and behavioural description. occam programs are easily configured onto the hardware of a system or indeed, may specify the hardware of a system. The founding principle of occamis a minimalist approach which avoids unnecessary duplication of language mechanism, and is named after the 14th century philosopher William of Occam who proposed that invented entities should not be duplicated beyond necessity. This proposition has become known as “Occam’s razor”. The occam programming language arises from the concepts founded by David May in EPL (Experimental Programming Language) and Tony Hoare in CSP (Communicating Sequential Processes). Since its conception in 1982 occam has been, and continues to be under development at INMOS Limited, in the United Kingdom, under the direction of David May. The support for large programs provided by occam3 is based on principles found in many current programming languages which have been refined at INMOS by Geoff Barrett. The development of the INMOS transputer, a device which places a microcomputer on a single chip, has been closely related to occam, its design and implementation. The transputer reflects the occam architectural model, and may be considered an occam machine. occam is the language of the

transputer and as such, when used to program a single transputer or a network of transputers, provides the equivalent efficiency to programming a conventional computer at assembler level. However, this manual does not make any assumptions about the hardware implementation of the language or the target system. occam is a trademark of the INMOS group of companies.