Autocode
Encyclopedia
Autocode is the name of a family of "simplified coding systems", later called programming languages
, devised in the 1950s and 1960s for a series of digital computers at the Universities of Manchester
and Cambridge
. Autocode was a generic term; the autocodes for different machines were not necessarily closely related as are, for example, the different versions of the single language FORTRAN
.
The first autocode and its compiler were developed by Alick Glennie
in 1952 for the Mark 1
computer at the University of Manchester and is considered by some to be the first compiled
programming language.
The second autocode was developed for the Mark 1 by R. A. Brooker
in 1954 and was called the "Mark 1 Autocode".
Brooker also developed an autocode for the Ferranti Mercury
in the 1950s in conjunction with the University of Manchester.
Mercury Autocode had a limited repertoire of variables
a-z and a'-z' and, in some ways resembled early versions of the later Dartmouth BASIC
language. It pre-dated ALGOL
, having no concept of stack
s and hence no recursion
or dynamically-allocated arrays. In order to overcome the relatively small store size available on Mercury, large programs were written as distinct "chapters", each of which constituted an overlay
. Some skill was required to minimise time-consuming transfers of control between chapters. This concept of overlays from drum
under user control became common until virtual memory
became available in later machines. Slightly different dialects of Mercury Autocode were implemented for the Ferranti Atlas
(distinct from the later Atlas Autocode
) and the ICT 1300
and 1900
range.
The version for the EDSAC 2
was devised by D. F. Hartley of University of Cambridge Mathematical Laboratory in 1961. Known as EDSAC 2 Autocode, it was a straight development from Mercury Autocode adapted for local circumstances, and was noted for it object code optimisation and source-language diagnostics which were advanced for the time. A version was developed for the successor TItan (the prototype Atlas 2 computer) as a temporary stop-gap while a more substantially advanced language known as CPL was being developed. CPL was never completed but did give rise to BCPL (developed by M. Richards), which in turn led to B and ultimately C. A contemporary but separate thread of development, Atlas Autocode
was developed for the University of Manchester Atlas 1
machine.
High-level programming language
A high-level programming language is a programming language with strong abstraction from the details of the computer. In comparison to low-level programming languages, it may use natural language elements, be easier to use, or be from the specification of the program, making the process of...
, devised in the 1950s and 1960s for a series of digital computers at the Universities of Manchester
University of Manchester
The University of Manchester is a public research university located in Manchester, United Kingdom. It is a "red brick" university and a member of the Russell Group of research-intensive British universities and the N8 Group...
and Cambridge
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
. Autocode was a generic term; the autocodes for different machines were not necessarily closely related as are, for example, the different versions of the single language FORTRAN
Fortran
Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
.
The first autocode and its compiler were developed by Alick Glennie
Alick Glennie
Alick Edwards Glennie was a British computer scientist, most famous for having developed Autocode, which many people regard as the first ever computer compiler. Glennie worked with Alan Turing on several projects, including the Manchester Mark 1...
in 1952 for the Mark 1
Manchester Mark 1
The Manchester Mark 1 was one of the earliest stored-program computers, developed at the Victoria University of Manchester from the Small-Scale Experimental Machine or "Baby" . It was also called the Manchester Automatic Digital Machine, or MADM...
computer at the University of Manchester and is considered by some to be the first compiled
Compiler
A compiler is a computer program that transforms source code written in a programming language into another computer language...
programming language.
The second autocode was developed for the Mark 1 by R. A. Brooker
Tony Brooker
Tony Brooker graduated in Mathematics from Imperial College in 1945 and returned there in 1947 as Assistant Lecturer. His first computer project was the construction of a fast multiplier unit from electro-mechanical relays. This was taken over by Professor K D Tocher and incorporated into ICCE, the...
in 1954 and was called the "Mark 1 Autocode".
Brooker also developed an autocode for the Ferranti Mercury
Ferranti Mercury
The Mercury was an early 1950s commercial computer built by Ferranti. It was the successor to the Ferranti Mark 1, adding a floating point unit for improved performance, and increased reliability by replacing the Williams tube memory with core memory and using more solid state components...
in the 1950s in conjunction with the University of Manchester.
Mercury Autocode had a limited repertoire of variables
Variable (programming)
In computer programming, a variable is a symbolic name given to some known or unknown quantity or information, for the purpose of allowing the name to be used independently of the information it represents...
a-z and a'-z' and, in some ways resembled early versions of the later Dartmouth BASIC
Dartmouth BASIC
Dartmouth BASIC is the original version of the BASIC programming language. It is so named because it was designed and implemented at Dartmouth College...
language. It pre-dated ALGOL
ALGOL
ALGOL is a family of imperative computer programming languages originally developed in the mid 1950s which greatly influenced many other languages and became the de facto way algorithms were described in textbooks and academic works for almost the next 30 years...
, having no concept of stack
Call stack
In computer science, a call stack is a stack data structure that stores information about the active subroutines of a computer program. This kind of stack is also known as an execution stack, control stack, run-time stack, or machine stack, and is often shortened to just "the stack"...
s and hence no recursion
Recursion
Recursion is the process of repeating items in a self-similar way. For instance, when the surfaces of two mirrors are exactly parallel with each other the nested images that occur are a form of infinite recursion. The term has a variety of meanings specific to a variety of disciplines ranging from...
or dynamically-allocated arrays. In order to overcome the relatively small store size available on Mercury, large programs were written as distinct "chapters", each of which constituted an overlay
Overlay (programming)
In a general computing sense, overlaying means "replacement of a block of stored instructions or data with another" Overlaying is a programming method that allows programs to be larger than the computer's main memory...
. Some skill was required to minimise time-consuming transfers of control between chapters. This concept of overlays from drum
Drum memory
Drum memory is a magnetic data storage device and was an early form of computer memory widely used in the 1950s and into the 1960s, invented by Gustav Tauschek in 1932 in Austria....
under user control became common until virtual memory
Virtual memory
In computing, virtual memory is a memory management technique developed for multitasking kernels. This technique virtualizes a computer architecture's various forms of computer data storage , allowing a program to be designed as though there is only one kind of memory, "virtual" memory, which...
became available in later machines. Slightly different dialects of Mercury Autocode were implemented for the Ferranti Atlas
Atlas Computer (Manchester)
The Atlas Computer was a joint development between the University of Manchester, Ferranti, and Plessey. The first Atlas, installed at Manchester University and officially commissioned in 1962, was one of the world's first supercomputers, considered to be the most powerful computer in the world at...
(distinct from the later Atlas Autocode
Atlas Autocode
Atlas Autocode was a programming language developed around 1965 at Manchester University for the Atlas Computer. It was developed by Tony Brooker and Derrick Morris as an improvement on the ALGOL programming languages, removing some of Algol's poorer features such as "passing parameters by name"...
) and the ICT 1300
ICT 1301
The ICT 1301 and its smaller derivative ICT 1300 were early business computers from International Computers and Tabulators. Typical of mid-sized machines of the era they used core memory, drum storage and punched cards, but they were unusual in that they were based on decimal logic instead of...
and 1900
ICT 1900 series
ICT 1900 was the name given to a series of mainframe computers released by International Computers and Tabulators and later International Computers Limited during the 1960s and '70s...
range.
The version for the EDSAC 2
EDSAC
Electronic Delay Storage Automatic Calculator was an early British computer. The machine, having been inspired by John von Neumann's seminal First Draft of a Report on the EDVAC, was constructed by Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory in England...
was devised by D. F. Hartley of University of Cambridge Mathematical Laboratory in 1961. Known as EDSAC 2 Autocode, it was a straight development from Mercury Autocode adapted for local circumstances, and was noted for it object code optimisation and source-language diagnostics which were advanced for the time. A version was developed for the successor TItan (the prototype Atlas 2 computer) as a temporary stop-gap while a more substantially advanced language known as CPL was being developed. CPL was never completed but did give rise to BCPL (developed by M. Richards), which in turn led to B and ultimately C. A contemporary but separate thread of development, Atlas Autocode
Atlas Autocode
Atlas Autocode was a programming language developed around 1965 at Manchester University for the Atlas Computer. It was developed by Tony Brooker and Derrick Morris as an improvement on the ALGOL programming languages, removing some of Algol's poorer features such as "passing parameters by name"...
was developed for the University of Manchester Atlas 1
Atlas Computer (Manchester)
The Atlas Computer was a joint development between the University of Manchester, Ferranti, and Plessey. The first Atlas, installed at Manchester University and officially commissioned in 1962, was one of the world's first supercomputers, considered to be the most powerful computer in the world at...
machine.