CHLF(ID:4925/chl002)Extension of Mercury Autocode to run on IBM 7090for Cern, Harwell, London, Farnborough autocode Co-operative effort between CERN, Harwell Atomic plant, University of London Computer Unit and Royal Aircraft Establishment, Farnborough to make an extended MERCURY AUTOCODE DC Cooper et al Operational Nov 1961 Places
Related languages
References: in [ACM] CACM 6(03) (Mar 1963) view details in [ACM] CACM 6(03) (Mar 1963) view details EXCHLF AUTOCODE - or simply EXCHLF - is a computer programming language. It is a development of MERCURY AUTOCODE, one of the first non-basic programming languages, which was developed especially for the Ferranti MERCURY computer principally by R. A. Brooker of Manchester University. Various extensions and modifications of MERCURY AUTOCODE have been produced from time to time; in particular, the term CHLF AUTOCODE was applied to an extended version of MERCURY AUTOCODE developed collaboratively by and used at the MERCURY installations at CERN, Harwell, London, and RAE Farnborough. The most substantial innovation in CHLF AUTOCODE was the CHLF Routine, due to Dr D. C. Cooper of the then University of London Computer Unit. Both MERCURY AUTOCODE and the original CHLF AUTOCODE as programming languages preserved a particular orientation to MERCURY as the implementing computer, A facility for incorporating MERCURY machine-language instructions into AUTOCODE programs was much used in order to supplement the deficiencies of AUTOCODE itself. The replacement of the London MERCURY by an ATLAS computer was preceded by the development at London of an extended CHLF AUTOCODE; this extension, called CHLF3 AUTOCODE, came into use as the standard version of AUTOCODE for MERCURY at the University of London Computer Unit on 1 April 1962. Its new features were chiefly such as to obviate the necessity for machine-language instructions, so as to facilitate the transition from MERCURY to ATLAS. Its development and implementation on MERCURY were due principally to Alan Fairbourn of ULCU, as was its eventual implementation on ATLAS. It then became clear that CHLF3 AUTOCODE did not take full advantage of the capabilities of ATLAS; and it was found possible to make still further extensions and improvements by means of appropriate modifications to the ATLAS Compiler for GHLF3 AUTOCODE. The name EXCHLF AUTOCODE was applied to this new extended language; the EXCHLF Compiler came into use on ATLAS in October 1965. By this time the AUTOCODE language had become, rather like a developed human language, a mixture of primitive and sophisticated elements; it was clear that the next stage of development must include rationalisation as well as further extension. The EXCHLF Compiler introduced in September 1966, to which this Handbook applies, nevertheless does not render obsolete (in the sense of unavailable) any of the facilities of its predecessors (with a few minor exceptions). However a substantial number of features and facilities have been rendered obsolescent, in that they are now provided for as particular cases of more general facilities, or are incompatible with newer facilities, or are irrelevant to execution by ATLAS. In order therefore to assist their transition from obsolescence to oblivion, such features and facilities are not described in this Handbook. In other words, the process of rationalisation has been applied to the Handbook but not yet to the Compiler. The implementation on ATLAS of the various stages of the EXCHLF development is due to Gailean Davidson, with the assistance of Diana Lawrence and, more recently, Margaret Pragnell, all of ULICS. Benedict Nixon (ULICS)has been closely associated in a consultative capacity with all the stages of development outlined above. Another substantial extension of MERCURY AUTOCODE has been produces by ICT Ltd.; it is CAlled Extended Mercury Autocode or EMA. It includes many of the features of the early CHLF AUTOCODE as well as having peculiarities of its own; but it is not necessarily the case that a EXCHLF program is an acceptable EMA program and vice-versa, in spite of the considerable common ground. in [ACM] CACM 6(03) (Mar 1963) view details All early computer users wrote their programs in machine code so programming was something of a black art. R.A. Brooker in Manchester (now Professor and pro-Vice Chancellor at Essex) devised an Autocode for the Mark-l and Mark-I*, which was a simple, easy-to-Iearn and easy-to-use high level language - not very high, to be sure, and very slow in execution, but a great improvement on machine code if you had only a fairly small program to write. We introduced this to Harwell and it caught on. When Ferranti embarked on building Mercury - based, as I said, on the next Manchester design - Brooker decided to write a new Autocode which, because of the higher basic speed and better facilities offered by Mercury, would be much more powerful and flexible and much faster. He spent a lot of time with us at Harwell discussing what should go into the new system, so that Harwell certainly had a significant influence on what he produced. The system, Mercury Autocode, proved a great success. Although simple when compared with modern high-level languages it provided an admirable range of facilities and was very easy to learn. With various enhancements it had a remarkably long life; a compiler for the final version, called CHLF because it was produced by a collaboration between CERN, Harwell, London (University) and Farnborough (RAE), was written for Atlas and was still in use in the early 1970's. in [ACM] CACM 6(03) (Mar 1963) view details Resources
|