Imp - Edinburgh Computer History

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The first Imp compiler at Edinburgh was the KDF-9 compiler (written by P.Bratley, D.J.Rees, P.D.Schofield & H.Whitfield), based on Atlas Autocode. The source of this compiler was recently recovered from paper tape by Ian Young and Chris Whitfield (that was in interesting saga in itself). If you examine the source you'll see a significant part of it is embedded assembler. The next major development was the first truly portable version which was written entirely in Imp in 1970 for the ICL 4/75 - the first of a long series of bootstrapping operations which continues to this day. The ERCC dialect of Imp (see the Imp Language Manual) is really the canonical Imp; and the final version of that dialect, which attempted to define a common subset of the language that would behave the same if it were compiled under the Computer Science department's Imp77 compiler, is fully documented in the online help information for Imp80 extracted from the EMAS help system.

The first published article on the IMP language and Compiler by PeterStephens, appeared in The Computer Journal, Vol 17 Issue 3 pp 216-223.

Peter Schofield has written some helpful Notes on IMP programming for newcomers to the language.

Other references:

IMP is a descendant of the ATLAS Autocode, developed during 1966-1969 at the Edinburgh University. IMP is a language which the developers describe as being "of the ALGOL type" [Barritt, 1970]. However, it contains many of the facilities which are in PL/I, and follows the syntax of neither. For example, IMP contains a simple form of data structure, significant control over the storage mapping of data, commands for moving parts of words, statements for character handling, string operations, input/output commands, compiler generated checks at object time. Machine language instructions can be inserted inline. IMP compilers exist for the ICL System 4 machines, IBM 360, PDP-9 and 15, and UNIVAC 1108. -- Sammet, Jean E. "Brief survey of languages used for systems implementation" § SIGPLAN Notices 6(10) October 1971 Proceedings of the SIGPLAN symposium on Languages for system implementation 1971, Lafayette, Indiana, United States; October, 1971

Sources:

Imp 9.18 for ICL 4/75. (Use this one to compile EMAS-4/75 code such as IMPIS. Needs an implementation of LPUT to be complete.)