EDSAC

This was an early computer in England.

It was built to help a university. A man named Maurice Wilkes led the team.

The machine used paper tape to get jobs. It could also print out lists of numbers. Its first job was to find square numbers.

People used it to solve real problems. It was a very important machine for science.

The EDSAC was an early computer in England.

Maurice Wilkes led the team that built it. They worked at the University of Cambridge. It was a very special machine. It was one of the first computers to use a stored program. This means the computer keeps its instructions and its data in the same memory.

To give the computer jobs, people used five-hole paper tape. The machine could print results on a teleprinter. On May 6, 1949, the EDSAC ran its first program. A woman named Beatrice Worsley wrote it. The program calculated a list of square numbers. It also found prime numbers.

The computer used mercury delay lines for its memory. These were like small tanks that held data. At first, the memory was quite small. It could only hold 512 words. Later, the team added more to hold 1024 words. The EDSAC helped many people with science research. It was even used to help write the first programming textbook. This machine worked until 1958.

The EDSAC was a very important early computer in England.

It was built at the University of Cambridge Mathematical Laboratory. This machine was one of the first to use a stored-program design. This design means the computer keeps its instructions and its data in the same memory. This makes the machine very flexible for different tasks. It was the second electronic digital computer of this kind to enter regular service.

The machine helped many researchers solve real science problems.

How did the EDSAC work? It used mercury delay lines for its memory. You can think of these like small tanks that held data. The computer also used vacuum tubes for its logic. To give the machine jobs, people used five-hole punched paper tape. The computer would read this tape and then print results on a teleprinter.

It used electricity to run, consuming 11 kW of power. Most instructions happened in 1.5 ms, but multiplication took 6 ms. The machine used binary numbers to do its math.

The idea for the EDSAC came from earlier work. In 1945, John von Neumann wrote a report about the EDVAC. This report described the concept of a stored-program computer. Maurice Wilkes learned about these ideas at the Moore School Lectures in 1946. He then began developing the EDSAC I in October of that year.

Wilkes even proposed microprogramming to make computer design easier. This new way of designing computers was later used by many others.

Many people worked on making the EDSAC useful. On May 6, 1949, the machine ran its very first programs. A woman named Beatrice Worsley wrote the first program. It calculated a list of square numbers from 0 to 99. It also found prime numbers.

In 1953, David Wheeler added an index register to the hardware. The memory grew from 512 words to 1024 words over time. The EDSAC stayed in use until it was shut down on July 11, 1958.

The EDSAC helped start the modern world of software. It used the world's first assembler, which is a tool for writing programs. This was a very early version of what programmers use today. David Wheeler even invented the concept of a subroutine. A subroutine is a piece of code that performs a specific task. In 1951, Wilkes, Wheeler, and Stanley Gill wrote the first programming textbook.

Their work helped teach others how to use these amazing new machines.

The Electronic Delay Storage Automatic Calculator, known as EDSAC, was a pioneering British computer.

It was built at the University of Cambridge Mathematical Laboratory to serve the university's research needs. EDSAC was the second electronic digital stored-program computer to enter regular service. The first was the Manchester Mark 1. The concept of a stored-program computer is very important. It means the computer stores both its instructions, or programs, and its data in the same memory. This allows for much greater flexibility and automation in computation.

The design of EDSAC was inspired by the work of John von Neumann. In 1945, von Neumann wrote a report about the EDVAC. This document described the Von Neumann architecture, which is the idea of storing programs and data together. Maurice Wilkes began developing the EDSAC I in October 1946. He had attended the Moore School Lectures in 1946. There, he learned about the ENIAC and the proposed EDVAC. Wilkes also proposed microprogramming. This is a system that simplifies the logical design of computers. Microprogramming later became a standard practice in the computer industry.

Technically, EDSAC relied on specific components to function. It used mercury delay lines for its memory. These delay lines were arranged in two batteries, which were often called "tanks." The machine also used derated vacuum tubes for its logic.

To provide instructions, users utilized five-hole punched tape. The computer would then output information via a teleprinter. The machine consumed 11 kW of electricity to operate. Most ordinary instructions had a cycle time of 1.5 ms. However, multiplication was slower, taking 6 ms to complete.

The memory system of EDSAC evolved over time. Initially, the main memory was limited to 512 words. Each word contained 18 bits. However, the topmost bit was always unavailable due to timing problems. This meant only 17 bits were actually used for data. The machine used two's complement binary numbers for its calculations. Numbers could be 17 bits long or 35 bits long. By 1952, a second battery of delay lines was added. This eventually allowed for a full 1024-word store. By 1955 or 1956, the full capacity was available. This expansion allowed programs to grow larger than the original 800-word limit.

EDSAC's first successful run occurred on May 6, 1949.

The very first program was written by Beatrice Worsley. She traveled from Canada to study the machine. This first program calculated a table of square numbers from 0 to 99. It also produced a list of prime numbers. In 1953, David Wheeler added an index register to the hardware. This was an extension to the original design. This addition helped programmers manage data more effectively. The machine remained in service until it was shut down on July 11, 1958.

The computer also helped birth the software industry. In May 1949, the machine used the world's first assembler. An assembler is a tool that translates code. This primitive relocating assembler used only 31 words. David Wheeler, who earned the first Computer Science PhD on this project, also invented the subroutine. A subroutine is a sequence of instructions that performs a specific task. Programmers used "Wheeler Jumps" to call these subroutines. They also developed early job queues. Operators would hang paper tapes on a line for the machine to process. This is very similar to how modern computers handle tasks.

EDSAC's influence reached far beyond the University of Cambridge. The design of EDSAC served as a basis for the LEO I. This was a commercial computer developed by J. Lyons & Co. Ltd. In 1951, Wilkes, Wheeler, and Stanley Gill published a book. This was the first programming textbook. It was titled "The Preparation of Programs for an Electronic Digital Computer." This work helped standardize how people learned to interact with computers. The legacy of EDSAC lives on in the fundamental way all modern computers are designed and programmed.