Mary Lee Woods
Encyclopedia
Mary Lee Woods, now Mrs C M Berners-Lee (born 12 March 1924) is a British
mathematician
and computer programmer
who worked in a team that developed programs for the Manchester University
Mark 1
, Ferranti Mark 1 and Mark 1 Star computers. She is married to Conway Berners-Lee
, also in the team. Their eldest son, Sir Tim Berners-Lee
, invented the World Wide Web
.
From 1942-1944, she took a wartime compressed two-year degree course in mathematics at the University of Birmingham
. She then worked for the Telecommunications Research Establishment
at Malvern
until 1946 when she returned to take the third year of her degree. She worked at the Mount Stromlo Observatory
in Canberra
, Australia
from 1947 to 1951 when she joined Ferranti
in Manchester
as a computer programmer.
The programming group was led by John Bennett
. Members of this team found it useful to commit to memory the following sequence of characters which represented the numbers 0 to 31 in the International Telegraph Alphabet No. 1 (Baudot)
5-bit binary code of the paper tape that was used for input and output.
Mrs Berners-Lee worked on both the Ferranti Mark 1 and the Ferranti Mark 1* computers. Programming in those days was very different to the situation today. Programs were written in machine code
, using the basic binary digits (bits)
with which all machines operate. Every bit had to be right; there was plenty of room for error, but there was opportunity to be cunning too. She found it to be great fun. The machines used serial 40-bit arithmetic (with a double length accumulator
). This meant that here were considerable difficulties in scaling the variables in the program to maintain adequate arithmetic precision.
Another of the difficulties of programming related to the two-level store of the machines. There were eight pages
of Williams cathode ray tube (CRT)
random-access memory
as fast primary store, and 512 pages of secondary store on a magnetic drum
. Each page consisted of 32 40-bit words which appeared as 64 20-bit lines on the CRTs. The programmer had to control all transfers between electronic and magnetic storage, and the transfers were slow and had to be reduced to a minimum. For programs dealing with large chunks of data, such as matrices
, partitioning into page-sized chunks could be troublesome.
The Mark 1 machine worked in integer arithmetic and, because of their background in radar
, the engineers had built the machine to display the lines on the CRTs with the most significant bit on the right. This could be argued as logically sensible, but was changed for the more conventional system for the Mark 1*, which also worked in fractions, not integers. Also, the Baudot teleprinter code was abandoned for one that was in the following order.
Program errors were difficult to find and programmers were tempted to sit at the machine control desk watching the machine perform one instruction at a time to watch where it did the unintended thing. But machine time became more and more valuable. John Bennett suggested to Mrs Berners-Lee that she write a diagnostic program to print out the contents of the accumulator and particular store lines at specific points in the program so that diagnosis could take place away from the machine. The challenge of her routine 'Stopandprint' was that it had to monitor the program under diagnosis without interfering with it, and there was very little space in the fast store. With J M Bennett and D. G. Prinz, she was involved in writing interpretive subroutines that were used by the Ferranti group.
Program errors were one problem; machine errors were another. The computer frequently misread the binary digits. The engineers thought the mathematicians could compensate for this by programming arithmetic checks and the mathematicians would too readily assume that a wrong functioning was due to the machine when in fact it was due to a program error. There was inevitable friction between the mathematicians and the engineers. At the centre of this was a program that Mary Lee had written for inverting a matrix to solve 40 simultaneous equations
—a large number for those days. The long rows of data took too long for the machine to process without an error. On one occasion she took a dispute to Tom Kilburn
, who was second only to Professor Freddy Williams
on the engineering side. Tom Kilburn was polite but did not argue and she felt he was ignoring her complaint, but 50 years later when she asked him about this, he said that he had not argued "because I knew you were right".
All this was in the early 1950s when the programmers were about equal numbers of men and women. The women had to fight for equal pay. They also had to fight for the right to work on the computer at night, machine time being so precious that it was often the only time available.
After a period devoted to bringing up her children, she became a schoolteacher of mathematics and then a programmer using Basic
, Fortran
and other languages before retiring in 1987.
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
mathematician
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
and computer programmer
Programmer
A programmer, computer programmer or coder is someone who writes computer software. The term computer programmer can refer to a specialist in one area of computer programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to...
who worked in a team that developed programs for the Manchester University
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...
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...
, Ferranti Mark 1 and Mark 1 Star computers. She is married to Conway Berners-Lee
Conway Berners-Lee
Conway Berners-Lee is a British mathematician and computer scientist who worked in the team that developed the Ferranti Mark 1, the world's first commercial stored program electronic computer...
, also in the team. Their eldest son, Sir Tim Berners-Lee
Tim Berners-Lee
Sir Timothy John "Tim" Berners-Lee, , also known as "TimBL", is a British computer scientist, MIT professor and the inventor of the World Wide Web...
, invented the World Wide Web
World Wide Web
The World Wide Web is a system of interlinked hypertext documents accessed via the Internet...
.
From 1942-1944, she took a wartime compressed two-year degree course in mathematics at the University of Birmingham
University of Birmingham
The University of Birmingham is a British Redbrick university located in the city of Birmingham, England. It received its royal charter in 1900 as a successor to Birmingham Medical School and Mason Science College . Birmingham was the first Redbrick university to gain a charter and thus...
. She then worked for the Telecommunications Research Establishment
Telecommunications Research Establishment
The Telecommunications Research Establishment was the main United Kingdom research and development organization for radio navigation, radar, infra-red detection for heat seeking missiles, and related work for the Royal Air Force during World War II and the years that followed. The name was...
at Malvern
Malvern, Worcestershire
Malvern is a town and civil parish in Worcestershire, England, governed by Malvern Town Council. As of the 2001 census it has a population of 28,749, and includes the historical settlement and commercial centre of Great Malvern on the steep eastern flank of the Malvern Hills, and the former...
until 1946 when she returned to take the third year of her degree. She worked at the Mount Stromlo Observatory
Mount Stromlo Observatory
Mount Stromlo Observatory located just outside of Canberra, Australia, is part of the Research School of Astronomy and Astrophysics at the Australian National University .-History:...
in Canberra
Canberra
Canberra is the capital city of Australia. With a population of over 345,000, it is Australia's largest inland city and the eighth-largest city overall. The city is located at the northern end of the Australian Capital Territory , south-west of Sydney, and north-east of Melbourne...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
from 1947 to 1951 when she joined Ferranti
Ferranti
Ferranti or Ferranti International plc was a UK electrical engineering and equipment firm that operated for over a century from 1885 until it went bankrupt in 1993. Known primarily for defence electronics, the Company was once a constituent of the FTSE 100 Index but ceased trading in 1993.The...
in Manchester
Manchester
Manchester is a city and metropolitan borough in Greater Manchester, England. According to the Office for National Statistics, the 2010 mid-year population estimate for Manchester was 498,800. Manchester lies within one of the UK's largest metropolitan areas, the metropolitan county of Greater...
as a computer programmer.
The programming group was led by John Bennett
John Makepeace Bennett
Emeritus Professor John Makepeace Bennett AO, FTSE, was an early Australian computer scientist. He was Australia's first professor of computer science and the founding president of the Australian Computer Society...
. Members of this team found it useful to commit to memory the following sequence of characters which represented the numbers 0 to 31 in the International Telegraph Alphabet No. 1 (Baudot)
Baudot code
The Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII. It was the predecessor to the International Telegraph Alphabet No 2 , the teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of bits, sent over a...
5-bit binary code of the paper tape that was used for input and output.
Mrs Berners-Lee worked on both the Ferranti Mark 1 and the Ferranti Mark 1* computers. Programming in those days was very different to the situation today. Programs were written in machine code
Machine code
Machine code or machine language is a system of impartible instructions executed directly by a computer's central processing unit. Each instruction performs a very specific task, typically either an operation on a unit of data Machine code or machine language is a system of impartible instructions...
, using the basic binary digits (bits)
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
with which all machines operate. Every bit had to be right; there was plenty of room for error, but there was opportunity to be cunning too. She found it to be great fun. The machines used serial 40-bit arithmetic (with a double length accumulator
Accumulator
Accumulator may refer to:* Accumulator , in a CPU, a processor register for storing intermediate results* Accumulator , an apparatus for storing energy or power...
). This meant that here were considerable difficulties in scaling the variables in the program to maintain adequate arithmetic precision.
Another of the difficulties of programming related to the two-level store of the machines. There were eight pages
Paging
In computer operating systems, paging is one of the memory-management schemes by which a computer can store and retrieve data from secondary storage for use in main memory. In the paging memory-management scheme, the operating system retrieves data from secondary storage in same-size blocks called...
of Williams cathode ray tube (CRT)
Williams tube
The Williams tube or the Williams-Kilburn tube , developed in about 1946 or 1947, was a cathode ray tube used to electronically store binary data....
random-access memory
Random-access memory
Random access memory is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. Strictly speaking, modern types of DRAM are therefore not random access, as data is read in...
as fast primary store, and 512 pages of secondary store on a magnetic 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....
. Each page consisted of 32 40-bit words which appeared as 64 20-bit lines on the CRTs. The programmer had to control all transfers between electronic and magnetic storage, and the transfers were slow and had to be reduced to a minimum. For programs dealing with large chunks of data, such as matrices
Matrix (mathematics)
In mathematics, a matrix is a rectangular array of numbers, symbols, or expressions. The individual items in a matrix are called its elements or entries. An example of a matrix with six elements isMatrices of the same size can be added or subtracted element by element...
, partitioning into page-sized chunks could be troublesome.
The Mark 1 machine worked in integer arithmetic and, because of their background in radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
, the engineers had built the machine to display the lines on the CRTs with the most significant bit on the right. This could be argued as logically sensible, but was changed for the more conventional system for the Mark 1*, which also worked in fractions, not integers. Also, the Baudot teleprinter code was abandoned for one that was in the following order.
Program errors were difficult to find and programmers were tempted to sit at the machine control desk watching the machine perform one instruction at a time to watch where it did the unintended thing. But machine time became more and more valuable. John Bennett suggested to Mrs Berners-Lee that she write a diagnostic program to print out the contents of the accumulator and particular store lines at specific points in the program so that diagnosis could take place away from the machine. The challenge of her routine 'Stopandprint' was that it had to monitor the program under diagnosis without interfering with it, and there was very little space in the fast store. With J M Bennett and D. G. Prinz, she was involved in writing interpretive subroutines that were used by the Ferranti group.
Program errors were one problem; machine errors were another. The computer frequently misread the binary digits. The engineers thought the mathematicians could compensate for this by programming arithmetic checks and the mathematicians would too readily assume that a wrong functioning was due to the machine when in fact it was due to a program error. There was inevitable friction between the mathematicians and the engineers. At the centre of this was a program that Mary Lee had written for inverting a matrix to solve 40 simultaneous equations
Simultaneous equations
In mathematics, simultaneous equations are a set of equations containing multiple variables. This set is often referred to as a system of equations. A solution to a system of equations is a particular specification of the values of all variables that simultaneously satisfies all of the equations...
—a large number for those days. The long rows of data took too long for the machine to process without an error. On one occasion she took a dispute to Tom Kilburn
Tom Kilburn
Tom Kilburn CBE, FRS was an English engineer. With Freddie Williams he worked on the Williams Tube and the world's first stored-program computer, the Small-Scale Experimental Machine , while working at the University of Manchester.-Computer engineering:Kilburn was born in Dewsbury, Yorkshire and...
, who was second only to Professor Freddy Williams
Frederic Calland Williams
Sir Frederic Calland Williams CBE, FRS , known as 'Freddie Williams', was an English engineer....
on the engineering side. Tom Kilburn was polite but did not argue and she felt he was ignoring her complaint, but 50 years later when she asked him about this, he said that he had not argued "because I knew you were right".
All this was in the early 1950s when the programmers were about equal numbers of men and women. The women had to fight for equal pay. They also had to fight for the right to work on the computer at night, machine time being so precious that it was often the only time available.
After a period devoted to bringing up her children, she became a schoolteacher of mathematics and then a programmer using Basic
BASIC
BASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use - the name is an acronym from Beginner's All-purpose Symbolic Instruction Code....
, Fortran
Fortran
Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
and other languages before retiring in 1987.