Elliott 803 facts for kids
The Elliott 803 was a cool early computer made by a British company called Elliott Brothers in the 1960s. It was a medium-speed computer that used transistors, which were new and exciting at the time! About 211 of these computers were built and sold.
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History of the Elliott 803
The Elliott 803 was part of a family of computers that started with the 801 in 1957. Only a few of the earlier models, like the 802, were sold. The 803A came out in 1959, and the more popular 803B followed in 1960.
More than 200 Elliott 803 computers were delivered to customers. Each one cost about £29,000 in 1960, which was a lot of money back then! Most people bought the 803B version because it had more memory and could do math with decimal points faster.
One interesting use for the Elliott 803 was in the ISI-609, which was the world's first system for controlling industrial processes. It was used to collect data at the N-Reactor, a special nuclear reactor in the US. Many universities in Britain also had an Elliott 803 for their students and researchers.
Later, Elliott made a much faster computer called the Elliott 503 in 1963.
Today, only two complete Elliott 803 computers still exist. One is owned by the Science Museum in London, but you can't see it on display. The other one is at The National Museum of Computing (TNMoC) in Bletchley Park. This one is fully working, and visitors can often see it in action!
How the Elliott 803 Worked
The Elliott 803 was a "transistorised" computer, meaning it used transistors instead of older, bigger vacuum tubes. This made it smaller and more reliable. It stored information using magnetic-core memory, which was like tiny donut-shaped magnets that could hold data. It had either 4096 or 8192 "words" of memory, with each word holding 40 bits of information.
The main part of the computer, called the CPU, was in a large cabinet that was about 56 inches tall, 66 inches wide, and 16 inches deep. The computer's circuits were on printed circuit boards, and many wires connected everything.
There was also a second cabinet for the power supply. This was unusual because it used a large nickel–cadmium battery with a charger, acting like an early backup power system. If you had the larger memory, you needed a third cabinet for the extra storage!
To use the computer, operators had a control console (a big desk with buttons and lights), a Creed teleprinter (like a typewriter), and a fast paper punched tape reader and punch. Programs and data were fed into the computer using paper tapes. The tape reader could read 500 characters per second, and the punch could create tapes at 100 characters per second.
The operator's console was about 60 inches long. It let people manually enter instructions, look at data, and start or stop the machine. It even had a loudspeaker that made sounds based on the computer's activity, so operators could hear if it was working correctly! The whole system needed air conditioning and used about 3.5 kilowatts of power. A basic setup weighed around 680 kilograms (about 1500 pounds).
For storing lots of information, the Elliott 803 could use a special magnetic tape system. This system was unique because it used standard 35mm film stock (like what movies used to be on) coated with iron oxide. This film was used to record sound in the film industry, and Elliott's factory was near film studios, which explains why they used it! A 1000-foot reel of this film could hold about 1.3 megabytes of data.
Another interesting thing about the 803 was that it used magnetic cores not just for memory but also for its basic logic (like how a calculator does addition). These "logic cores" helped the computer make decisions. This was clever because transistors were expensive back then, and this design used fewer of them.
Computer Language and Instructions
The Elliott 803 understood instructions and data in "words" that were 39 bits long. It used a system called "2's complement" for math. The computer had a special "accumulator" register for calculations and an "auxiliary register" for bigger numbers.
Each instruction was made of two parts: a 6-bit "function" (what to do) and a 13-bit "address" (where to do it in memory). These 19-bit instructions were packed two into each 39-bit word. There was also a special "B-line" bit that could change how the second instruction worked, allowing for more flexible programming.
A single bit operation took 6 microseconds. Simple math instructions took about 576 microseconds, and more complex floating-point math took several milliseconds.
The original article had very detailed tables of instructions. For kids, it's enough to know that the computer had different groups of instructions for:
- Basic Math: Adding, subtracting, clearing numbers, and moving data around.
- Jumps: Telling the computer to skip to a different part of the program based on certain conditions (like if a number was negative or zero).
- Multiply, Divide, and Shift: Instructions for more complex math operations and moving bits around within a number.
- Floating-Point Math: Special instructions for numbers with decimal points (if the computer had that feature).
- Input/Output: Instructions for reading from the keyboard or paper tape, and sending information to the punch or other devices like a plotter (which could draw pictures!).
For example, to draw on a plotter, you would send specific instructions like "72 7169" to move the pen EAST or "72 7184" to lift the pen up.
How Programs Were Made
When you turned on the Elliott 803, it used "Initial Instructions" that were built into its memory. These instructions were like a tiny program that helped load other programs from paper tape.
Most programs were written using a simple assembler called the "Translation Input Routine." It didn't use easy-to-remember names for memory locations, so programmers had to keep track of numbers. There was also a simpler language called "Autocode" for easier programming, which didn't require as much knowledge of the computer's inner workings.
A very important part of the Elliott 803B (the one with more memory) was its ALGOL compiler. A compiler is a special program that translates code written in a human-readable language (like ALGOL) into the computer's machine code. This ALGOL compiler was largely written by a famous computer scientist named Tony Hoare. He later won a big award for his work in computer science.
The Elliott 803B at The National Museum of Computing can still run this ALGOL compiler today! You can even find videos online of it compiling and running simple programs.
NCR and "Do-It-Yourself" Computing
The Elliott 803 was also sold by another company called NCR, and it was branded as the NCR-Elliott 803 for business use.
Elliott and NCR even had a joint project called "Computer Workshop." This was a unique service where customers could learn to write their own computer programs! They would take 3-day courses and then come to Elliott's offices to operate the computers themselves. This was a very early example of "personal computing," where people directly interacted with the computer.
The cost to use the computer was about £8 per hour during the day in 1960, and cheaper at night. Many customers were engineers and architects who used the computers for things like designing buildings and analyzing structures.
Where the Elliott 803 Was Used
The Elliott 803 was used in many different places for various tasks:
- RMIT University in Australia used it for students.
- Brush Electrical Machines in the UK used it to design power transformers and motors.
- The G.P.O. (like the postal service) used it for electronics design and simulating telephone networks. They also used one at their Goonhilly Satellite Earth Station to calculate how satellites would move and to steer the giant dishes!
- Corah Knitware used two 803s for processing phone orders and planning production.
- Thornber Farms used one to process data about egg production for breeding chickens.
- The UK Potato Marketing Board used an 803 to create statistics and reports for 65,000 potato growers.
- Vickers, da Costa, a stockbroker, used an 803B for processing trades and payroll.
- The RAF No. 1 Radio School used an 803 to train the first RAF Computer Technician Apprentices.
- The Medical Research Council used one for detailed calculations to understand DNA and in early attempts to figure out the sequence of RNA.
- United Steel used an 803 to simulate processes in steel manufacturing.
- Many colleges and schools, like Banbury School, Felsted School, Haydon School, and Mill Hill School, also got second-hand Elliott 803s to teach students about computers. Some of these schools even had two computers, using one for parts!
Images for kids
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Parts from an Elliott 803B
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A magnetic film handler for the Elliott 803B
