English Electric DEUCE
Encyclopedia
The DEUCE was one of the earliest British
commercially available computer
s, built by English Electric
from 1955.
It was the production version of the Pilot ACE
, itself a cut down version of Alan Turing
's ACE.
The DEUCE had 1450 thermionic valves, and used mercury
delay lines
for its main memory; each of the 12 delay lines could store 32 instructions or data words of 32 bits. It adopted the then high 1 megahertz clock rate of the Pilot ACE. Input-output was via 80-column punch card equipment. The reader read cards at the rate of 200 per minute, while the card punch rate was 100 cards per minute. The DEUCE also had a 8192-word magnetic drum for main storage. The DEUCE could be fitted with paper tape equipment ; the reader speed was 850 characters per second, while the paper tape output speed was 25 characters per second. Magnetic tape units could also be attached. The automatic multiplier and divider units operated synchronusly (that is, other instructions could be executed while the multiplier and divider units were in operation). Two arithmetic units were provided for integer operations: one of 32 bits and another capable of performing 32-bit operations and 64-bit operations. Auto-increment and auto-decrement was provided on 8 registers from about 1957. Array arithmetic and array data transfers were permitted. Compared with contemporaries such as the Manchester Mark 1
, DEUCE was about ten times faster.
Programming the DEUCE involved added complication, as each instruction had to wait its turn in the delay line – the position of instructions in the store greatly affected performance. Reading data from a card reader was done in real-time – each row had to be read as it passed the read brushes, without stopping. Similarly for the card punch. The normal mode of reading and punching was binary. Decimal input and output was performed via software.
The front panel of the DEUCE featured two CRT
displays: one showed the current contents of registers, while the other showed the content of any one of the mercury delay line stores.
The first three machines were delivered in the spring of 1955; in late 1958 a DEUCE Mark II improved model appeared. This version employed a combined card reader and punch. The combined reader and punch behaved like the separate units on the earlier DEUCE Mark I machines; however, it was provided with hardware conversion of decimal data to BCD on input, and vice versa on output. Data could be read in and punched simultaneously at 100 cards per minute. The DEUCE Mark IIA provided seven extra mercury delay lines, each of 32 words.
A total of 33 DEUCE machines were sold between 1955 and 1964.
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...
commercially available computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
s, built by English Electric
English Electric
English Electric was a British industrial manufacturer. Founded in 1918, it initially specialised in industrial electric motors and transformers...
from 1955.
It was the production version of the Pilot ACE
Pilot ACE
The Pilot ACE was one of the first computers built in the United Kingdom, at the National Physical Laboratory in the early 1950s.It was a preliminary version of the full ACE, which had been designed by Alan Turing. After Turing left NPL , James H...
, itself a cut down version of Alan Turing
Alan Turing
Alan Mathison Turing, OBE, FRS , was an English mathematician, logician, cryptanalyst, and computer scientist. He was highly influential in the development of computer science, providing a formalisation of the concepts of "algorithm" and "computation" with the Turing machine, which played a...
's ACE.
The DEUCE had 1450 thermionic valves, and used mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
delay lines
Delay line memory
Delay line memory was a form of computer memory used on some of the earliest digital computers. Like many modern forms of electronic computer memory, delay line memory was a refreshable memory, but as opposed to modern random-access memory, delay line memory was serial-access...
for its main memory; each of the 12 delay lines could store 32 instructions or data words of 32 bits. It adopted the then high 1 megahertz clock rate of the Pilot ACE. Input-output was via 80-column punch card equipment. The reader read cards at the rate of 200 per minute, while the card punch rate was 100 cards per minute. The DEUCE also had a 8192-word magnetic drum for main storage. The DEUCE could be fitted with paper tape equipment ; the reader speed was 850 characters per second, while the paper tape output speed was 25 characters per second. Magnetic tape units could also be attached. The automatic multiplier and divider units operated synchronusly (that is, other instructions could be executed while the multiplier and divider units were in operation). Two arithmetic units were provided for integer operations: one of 32 bits and another capable of performing 32-bit operations and 64-bit operations. Auto-increment and auto-decrement was provided on 8 registers from about 1957. Array arithmetic and array data transfers were permitted. Compared with contemporaries such as the Manchester 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...
, DEUCE was about ten times faster.
Programming the DEUCE involved added complication, as each instruction had to wait its turn in the delay line – the position of instructions in the store greatly affected performance. Reading data from a card reader was done in real-time – each row had to be read as it passed the read brushes, without stopping. Similarly for the card punch. The normal mode of reading and punching was binary. Decimal input and output was performed via software.
The front panel of the DEUCE featured two CRT
Cathode ray tube
The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...
displays: one showed the current contents of registers, while the other showed the content of any one of the mercury delay line stores.
The first three machines were delivered in the spring of 1955; in late 1958 a DEUCE Mark II improved model appeared. This version employed a combined card reader and punch. The combined reader and punch behaved like the separate units on the earlier DEUCE Mark I machines; however, it was provided with hardware conversion of decimal data to BCD on input, and vice versa on output. Data could be read in and punched simultaneously at 100 cards per minute. The DEUCE Mark IIA provided seven extra mercury delay lines, each of 32 words.
A total of 33 DEUCE machines were sold between 1955 and 1964.
External References
- Oral history interview with Donald W. Davies, Charles Babbage InstituteCharles Babbage InstituteThe Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....
, University of Minnesota. Davies describes computer projects at the U.K. National Physical Laboratory, from the 1947 design work of Alan TuringAlan TuringAlan Mathison Turing, OBE, FRS , was an English mathematician, logician, cryptanalyst, and computer scientist. He was highly influential in the development of computer science, providing a formalisation of the concepts of "algorithm" and "computation" with the Turing machine, which played a...
to the development of the two ACE computers. Davies discusses a much larger, second ACE, and the decision to contract with English ElectricEnglish ElectricEnglish Electric was a British industrial manufacturer. Founded in 1918, it initially specialised in industrial electric motors and transformers...
Company to build the DEUCE -- which he calls the first commercially produced computer in Great Britain.