NEWP

NEWP (or the New Executive Programming Language) is a high-level programming language used on the Unisys MCP systems. The language is used to write the operating system and other system utilities, although it can also be used to write user software as well. Several constructs separate it from extended ALGOL on which it is based. Language operators such as MEMORY which allows direct memory access are strictly used by programs running as the MCP.

Main constructs

NEWP is a block-structured language very similar to Extended ALGOL. It includes several features borrowed from other programming languages which help in proper software engineering. These include modules (and later, super-modules) which group together functions and their data, with defined import and export interfaces. This allows for data encapsulation and module integrity. Since NEWP is designed for use as an operating system language, it permits the use of several unsafe constructs. Each block of code can have specific unsafe elements permitted. Unsafe elements are those only permitted within the operating system. These include access to the tag of each word, access to arbitrary memory elements, low-level machine interfaces, etc. If a program does not make use of any unsafe elements, it can be compiled and executed by anyone. If any unsafe elements are used, the compiler marks the code as non-executable. It can still be executed if blessed by a security administrator.