English Electric DEUCE facts for kids
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| Also known as | Digital Electronic Universal Computing Engine |
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| Manufacturer | English Electric |
| Release date | 1955 |
| Discontinued | 1964 |
| Units shipped | 33 |
| CPU | thermionic valve-based |
| Memory | mercury delay lines 384 32-bit words (Mark I and Mark II) 608 32-bit words (Mark IIA) |
| Storage | 8192-word magnetic drum |
| Display | 2 × CRTs |
| Predecessor | Pilot ACE |
The DEUCE (which stands for Digital Electronic Universal Computing Engine) was one of the first computers made in Britain that people could buy. The company English Electric built it starting in 1955.
DEUCE was like a bigger, more developed version of an earlier computer called the Pilot ACE. The Pilot ACE itself was a smaller version of a computer designed by the famous mathematician Alan Turing, called the ACE.
Contents
How the DEUCE Computer Worked
Inside the DEUCE: Parts and Power
The DEUCE computer used 1,450 thermionic valves, which are like old-fashioned light bulbs that control electricity. For its main memory, it used special tubes filled with mercury called delay lines. Each of these 12 delay lines could hold 32 pieces of information, called "words," each 32 bits long.
The DEUCE ran at a speed of 1 megahertz, which was very fast for its time. This speed came from the Pilot ACE computer.
Getting Information In and Out
To put information into the DEUCE and get it out, people used Hollerith punch-card machines. These machines used cards with holes punched in them to represent data. The computer could read 200 cards every minute. It could also punch holes into 100 cards per minute to show results.
The DEUCE also had a large magnetic drum for storing more information. This drum could hold 8,192 words. It had special movable parts that could read and write information quickly.
Other Ways to Connect
Sometimes, the DEUCE could also use paper tape equipment. This tape could read information very fast, at 850 characters per second. However, it could only write information back onto the tape much slower, at 25 characters per second.
Some DEUCE computers even had special magnetic tape units attached. This allowed them to store and read even more data.
How DEUCE Handled Math
The DEUCE had special parts for doing math like multiplication and division. These parts could work on their own, meaning the computer could do other tasks at the same time. It had two main parts for math: one for 32-bit numbers and another that could handle both 32-bit and 64-bit numbers.
Compared to other computers of its time, like the Manchester Mark 1, the DEUCE was about ten times faster.
Seeing What the Computer Was Doing
The front of the DEUCE computer had two CRT screens, which looked like small televisions. One screen showed what was currently in the computer's main memory parts. The other screen could show the information stored in any of the mercury delay lines. This helped people see what the computer was working on.
Upgrades to the DEUCE
Around 1958, an improved version called the DEUCE Mark II came out. This model had a combined machine that could both read and punch cards. It also had special hardware to automatically change text and numbers into a format the computer understood.
Later, the DEUCE Mark IIA was released. This version had seven extra mercury delay lines. This meant it could store 224 more words of information that it could access very quickly.
How People Programmed DEUCE
Programming Languages for DEUCE
To tell the DEUCE what to do, people used different programming languages. Some of the main ones were GEORGE, ALPHACODE, STEVE, TIP, GIP, and ALGOL. There were also special programs called "assemblers" like ZP43 and STAC that helped turn human-written code into computer instructions.
Understanding GEORGE
GEORGE was a very important programming language for the DEUCE. It was invented in 1957 by Charles Leonard Hamblin. GEORGE was a lot like the programming languages we use today. It used a special way of writing math problems called "Reverse Polish Notation."
For example, to calculate e = ay2 + by + c, you would write:
a y dup × × b y × + c + (e).
The word "dup" here means to make a copy of the previous number.
GEORGE also had a special "stack" that could hold up to 12 numbers. When you used a variable name, like 'd', its value was put on top of the stack. When you put a name in parentheses, like (d), the computer would save the number from the top of the stack into that variable.
Here's a simple GEORGE program that reads ten numbers and prints their squares:
1, 10 rep (i) read dup × punch ; ]
In this program, "dup" makes a copy of the number that was just read. Then, "×" multiplies these two copies together to get the square.
Using GIP for Math Problems
GIP (General Interpretive Programme) was a special program that helped manage other smaller programs, often called "bricks." It was very useful for running programs from the DEUCE's large library of math tools, especially for linear algebra (a type of math dealing with equations).
To use GIP, you would choose the "bricks" (programs) you needed, copy them onto punch cards, and then put them together. Then, you would write simple codes to tell the computer to do things like multiply matrices (tables of numbers), solve equations, or handle input and output.
A cool thing about GIP was that you didn't have to tell it the size of your numbers or matrices. The programs were "general," meaning they could work with any size of data as long as it fit on the magnetic drum.
STAC: The Smart Assembler
STAC was another important program for the DEUCE. It was a "macro-assembler." Most instructions were written in a simple way, like "13-16," meaning "copy the word from register 13 to register 16."
STAC was smart because it would figure out the best place to put each instruction in the computer's memory. This was important because of how the DEUCE's memory worked. STAC tried to make sure that as soon as one instruction finished, the next one was ready to go. This made the computer run as fast as possible.
How Programming Was Different
Programming the DEUCE was unique because of its "serial" memory (the delay lines). This meant that instructions had to be very carefully arranged. When one instruction finished, the next one needed to be ready to come out of the delay line right away. This was called "optimum programming." If instructions weren't placed perfectly, the computer would have to wait, making it slower.
Reading data from punch cards also had to be done in "real-time." This means the computer had to read each row of holes as the card moved, without stopping. The same was true for punching holes. The computer had to have the information ready at the exact moment the punch knives were in position.
The DEUCE had different types of fast memory. It had four "single-word" memory spots (32 bits each), three "double-word" spots, and two "quadruple-word" spots. You could access parts of these larger spots separately or as a whole group.
The main instruction memory used 12 mercury delay lines, each holding 32 words. One of these lines, DL11, was special. It acted as a buffer, helping to move data between the magnetic drum and the fast memory. The DEUCE could transfer data in many ways, from single words to blocks of 32 words at a time.
Building and Selling DEUCE Computers
The first three DEUCE computers were delivered in the spring of 1955. By late 1958, the improved DEUCE Mark II model was available. This version had a combined card reader and punch machine. It could also automatically convert text and numbers for the computer.
The DEUCE Mark IIA added seven more mercury delay lines. This gave the computer an extra 224 words of fast memory.
In total, 33 DEUCE machines were sold between 1955 and 1964. Two of these were bought by a company that made airplane engines, Bristol Siddeley.
A big reason for the DEUCE's success was its huge library of programs. It had over 1,000 programs and smaller routines that people could use.
See also
- List of vacuum tube computers
