What does the acronym EDSAC stand for?

EDSAC stands for the Electronic Delay Storage Automatic Calculator. This name reflects its core technology, using mercury delay lines for memory storage and electronic components for calculation.

What was EDSAC's historical significance in the context of stored-program computers?

EDSAC was the second electronic digital stored-program computer to enter regular service, following the Manchester Mark 1. It played a crucial role in the early development of computing.

When did EDSAC become operational and what was its first task?

EDSAC ran its first programs on May 6, 1949. Its initial tasks included calculating a table of square numbers and a list of prime numbers.

When was EDSAC retired from service?

EDSAC was shut down on July 11, 1958, after nearly a decade of operation, having been superseded by EDSAC 2.

Which company supported the EDSAC project, and what commercial computer resulted from this collaboration?

J. Lyons & Co. Ltd. supported the EDSAC project, aiming to develop a commercially applicable computer. This collaboration led to Lyons' development of the LEO I computer, which was based on the EDSAC design.

What seminal document influenced the design principles of EDSAC?

The design of EDSAC was significantly inspired by John von Neumann's *First Draft of a Report on the EDVAC*. This document described the concept of a stored-program computer, where both instructions and data reside in the same memory.

What is the Von Neumann architecture, as referenced in relation to EDSAC's inspiration?

The Von Neumann architecture is a computer design concept where computer instructions, or the program, are stored in the same memory as the data they operate on. This allows for greater flexibility and automation in computation.

What key concept did Maurice Wilkes propose after attending the Moore School Lectures in 1946?

After attending the Moore School Lectures, where he learned about the ENIAC and EDVAC, Maurice Wilkes proposed the concept of microprogramming. Microprogramming is a system designed to simplify the logical design of computers.

What type of memory technology did EDSAC utilize?

EDSAC primarily used mercury delay lines for its main memory. These were temperature-stabilized tanks containing mercury through which electrical signals were sent to store data.

What type of electronic components were used for the logic circuits in EDSAC?

EDSAC employed derated thermionic valves, commonly known as vacuum tubes, for its logic operations. Vacuum tubes were the standard electronic switching components in early computers.

What was the power consumption of the EDSAC computer?

EDSAC consumed approximately 11 kilowatts (kW) of electricity. This was a significant amount of power for the time.

Describe the memory capacity and word size of EDSAC.

Initially, EDSAC had 512 18-bit words of main memory. This was later upgraded to 1024 locations. However, due to timing issues, the top bit of each word was unusable, meaning only 17 bits were effectively available per word for data or instructions.

How were instructions structured in EDSAC?

An EDSAC instruction consisted of a five-bit instruction code, one spare bit, a 10-bit operand (often a memory address), and one length bit. The length bit determined whether the instruction operated on a single 17-bit word or a double 35-bit word (two consecutive words).

How did EDSAC represent instruction codes?

EDSAC used a mnemonic system where each instruction code was represented by a single character, specifically the EDSAC character code for a letter. For example, the Add instruction used the character code for the letter A.

What number system and representation did EDSAC use for calculations?

EDSAC used two's complement binary numbers for internal calculations. Numbers could be either 17 bits (one word) or 35 bits (two words) long.

How did EDSAC handle fixed-point arithmetic, particularly in its multiplier?

The multiplier in EDSAC was designed to treat numbers as fixed-point fractions within the range of -1 to less than 1. This means the binary point was considered to be immediately to the right of the sign bit.

What was the capacity of EDSAC's accumulator, and why was it significant?

The accumulator in EDSAC could hold 71 bits, including the sign. This large capacity allowed for the multiplication of two 35-bit numbers without losing any precision.

Which common arithmetic operation was notably absent as a direct instruction in EDSAC?

EDSAC did not have a direct division instruction. Programmers had to use supplied subroutines to perform division.

How did users prepare programs for the EDSAC?

Users prepared their programs by punching them, typically in assembler code, onto five-hole punched tape. They became adept at reading these tapes by holding them up to the light.

What was the function of the initial orders in EDSAC?

The initial orders were hard-wired onto uniselector switches and loaded into the computer's memory at startup. By May 1949, these initial orders provided a primitive relocating assembler, which was the world's first assembler.

Who wrote the very first program executed on EDSAC, and what did it compute?

Beatrice Worsley, who had traveled from Canada to study the machine, wrote the first program run on EDSAC. This program computed the squares of integers from 0 to 99.

What modern computing concept does the EDSAC's job queue system resemble?

The practice of machine operators selecting the next punched tape from a line and loading it into EDSAC is analogous to modern job queues in operating systems. This describes how programs were managed and executed sequentially.

How could programmers monitor the state of the EDSAC during program execution?

A cathode-ray tube screen could be configured to display the contents of specific memory locations, allowing programmers to observe if numbers were converging or how the program was progressing. Additionally, a loudspeaker connected to the accumulator's sign bit provided audible cues about program status.

What programming technique, considered outdated today, was commonly used on EDSAC due to hardware limitations?

Programmers frequently used self-modifying code on EDSAC. This technique involved altering the instructions themselves in memory, which was necessary because EDSAC lacked an index register for easily accessing array elements.

Who is credited with inventing the concept of a subroutine, and how did it function on EDSAC?

David Wheeler is credited with inventing the subroutine concept. On EDSAC, a subroutine was called by jumping to its starting address with the return address stored in the accumulator. The subroutine would then modify its own final jump instruction to return to the correct location after execution.

What was a Wheeler Jump in the context of EDSAC programming?

A Wheeler Jump refers to the specific method used in EDSAC programming where the return address, the location immediately following the jump instruction, was placed in the accumulator. This allowed subroutines to know where to return after completing their task.

What limitation prevented recursive subroutine calls on EDSAC?

Recursive calls were forbidden on EDSAC. This was partly due to the programming technique used, which relied on modifying the return address directly, and the lack of a stack structure that would typically support recursion.

How did the EDSAC's initial input routine handle the loading of subroutines?

The initial input routine was responsible for loading subroutines from punched tape into memory. It would record the starting location of the subroutine and adjust any internal memory references within the subroutine's code to match its actual loaded position.

What was the significance of the book The Preparation of Programs for an Electronic Digital Computer?

This 1951 book, authored by Wilkes, Wheeler, and Gill, is recognized as the first programming textbook, detailing how to program the EDSAC computer.

What was the primary purpose for which EDSAC was designed?

EDSAC was specifically designed to serve as a calculation support service for the University of Cambridge's Mathematical Laboratory. It was intended for practical, everyday research computations.

How did EDSAC contribute to the field of biology research?

Ronald Fisher, in collaboration with Wilkes and Wheeler, used EDSAC to solve a differential equation related to gene frequencies. This marked the first known application of a computer to research in biology.

What significant mathematical discovery was made using EDSAC in 1951?

In 1951, Miller and Wheeler used EDSAC to discover a 79-digit prime number, which was the largest known prime number at that time.

Name some Nobel laureates whose research benefited from EDSAC.

Nobel laureates John Kendrew and Max Perutz (Chemistry, 1962), Andrew Huxley (Medicine, 1963), and Martin Ryle (Physics, 1974) all acknowledged the crucial role EDSAC played in their respective research.

What important mathematical conjecture, considered a major unsolved problem, originated from EDSAC calculations?

The Birch and Swinnerton-Dyer conjecture, which relates the number of points on elliptic curves to their rank, was formulated based on numerical evidence gathered using EDSAC by Peter Swinnerton-Dyer in the early 1960s. It remains one of the most significant unsolved problems in mathematics.

What game, potentially the world's first video game, was developed for EDSAC in 1952?

Sandy Douglas developed OXO, a version of tic-tac-toe (noughts and crosses), for the EDSAC in 1952. It featured graphical output on a cathode-ray tube.

What was the successor to the EDSAC computer?

The successor to EDSAC was EDSAC 2, which was commissioned in 1958 and remained in use until 1965.

When was the plan to build a working replica of EDSAC announced, and where is it located?

The plan to build a working replica of EDSAC was announced on January 13, 2011. The replica is being constructed at the National Museum of Computing (TNMoC) on the Bletchley Park campus.

Who leads the EDSAC Replica Project?

The EDSAC Replica Project is led by Andrew Herbert, who was a student of Maurice Wilkes.

When were the initial components of the EDSAC replica first powered on?

The first parts of the EDSAC replica were switched on in November 2014.

How were the logical circuits for the EDSAC replica reconstructed?

The logical circuits were meticulously reconstructed through the development of a simulator and the re-examination of rediscovered original schematics. This documentation has been made publicly available.

What was the role of Maurice Wilkes in the development of EDSAC?

Maurice Wilkes led the team at the University of Cambridge Mathematical Laboratory that constructed EDSAC. He was inspired by the EDVAC report and proposed microprogramming for the machine.

How did EDSAC's programming techniques differ from modern practices?

Early EDSAC programming often involved techniques like self-modifying code and manual management of subroutine addresses due to the absence of features like index registers and procedure call instructions. This contrasts with modern programming, which relies on higher-level abstractions and automated memory management.

What was the Collate instruction on EDSAC?

The Collate instruction on EDSAC performed a bitwise AND operation on the accumulator and operand, and then added the result to the accumulator. It was a form of logical operation combined with addition.

What was the purpose of the index register added to EDSAC hardware in 1953?

An index register was added to EDSAC hardware in 1953, designed by David Wheeler. This component helped in addressing memory locations more flexibly, particularly useful for array processing and subroutines.

What was the initial memory capacity of EDSAC, and when was it expanded?

Initially, EDSAC had 512 17-bit words of main memory. This capacity was expanded in 1952 to 1024 17-bit words by adding a second battery of delay lines.

What did the newspaper The Star speculate about computers like EDSAC in 1949?

In June 1949, The Star speculated that computers like EDSAC might one day assist common people with tasks such as income tax and bookkeeping calculations, though it noted this was speculative and showed no signs of happening yet.

What is the significance of the EDSAC Replica Project?

The EDSAC Replica Project aims to build a fully working replica of the original EDSAC computer. This project allows for the preservation and demonstration of early computing technology and its historical context.

What was the cycle time for ordinary instructions on EDSAC?

The cycle time for most ordinary instructions on EDSAC was 1.5 milliseconds. Multiplication took a longer 6 milliseconds.

What type of input medium did EDSAC use?

EDSAC used five-hole punched tape for input. This was a common method for data and program entry in early computers.

What type of output device was used by EDSAC?

EDSAC used a teleprinter for output. This device printed the computer's results onto paper.

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What Was EDSAC?

A British Pioneer

The Electronic Delay Storage Automatic Calculator, or EDSAC, was a groundbreaking British computer developed at the University of Cambridge Mathematical Laboratory. It represented a significant leap forward in the nascent field of electronic computation.

Second to None

Inspired by John von Neumann's seminal work on the EDVAC, EDSAC was the second electronic digital stored-program computer to enter regular service, following closely behind the Manchester Mark 1. Its operational debut on May 6, 1949, marked a pivotal moment in computing history.

Foundation for Innovation

EDSAC was not merely a research project; it was designed to provide a computational service to the university. Its development and subsequent commercial adaptations, like the Lyons' LEO I, demonstrated the practical potential of stored-program computers, influencing generations of machines to come.

Genesis and Vision

The Von Neumann Influence

The conceptual roots of EDSAC trace back to 1945, with John von Neumann's influential "First Draft of a Report on the EDVAC." This document articulated the revolutionary concept of the stored-program computer, where both instructions and data reside in the same memory, forming the basis of the now-ubiquitous Von Neumann architecture.

Wilkes' Microprogramming

In August 1946, Maurice Wilkes, after attending the Moore School Lectures on ENIAC and EDVAC, proposed the concept of microprogramming. This innovative approach simplified the logical design of computers and would later become a standard industry practice. Armed with these insights, Wilkes initiated the EDSAC I project in October 1946.

Commercial Partnership

The project received crucial support from J. Lyons and Co. Ltd., a prominent catering company. This collaboration was driven by the ambition to develop commercially applicable computers, ultimately leading to Lyons' creation of the LEO I, a machine directly based on the EDSAC design.

Technical Architecture

Core Components

EDSAC employed cutting-edge (for its time) technology:

Logic: Utilized "derated" vacuum tubes, chosen for reliability.
Memory: Employed temperature-stabilized mercury delay lines, a common memory technology of the era.
Power: Consumed approximately 11 kW of electricity.
Cycle Time: Instructions executed in 1.5 milliseconds, with multiplication taking 6 ms.

Memory and Data Representation

The main memory initially comprised 512 18-bit words, later expanded to 1024 words. It utilized two's complement binary representation. Numbers were treated as fixed-point fractions (range -1 ≤ x < 1). The accumulator could hold 71 bits, enabling multiplication of two 35-bit numbers without precision loss.

Input and Output

User interaction and program loading were managed through:

Input: Five-hole punched tape, read by a dedicated reader.
Output: A teleprinter for printing results.

A magnetic tape drive was added in 1952 but proved unreliable for practical use.

Instruction Set

EDSAC featured a set of fundamental instructions, including Add, Subtract, Multiply-and-add, AND-and-add (Collate), Shifts, Load Multiplier, Store Accumulator, Conditional Goto, Read Input, Print Character, Round Accumulator, No-op, and Stop. Notably, it lacked a direct division instruction (requiring subroutines) and an unconditional jump instruction.

Pioneering Software

System Software

Upon startup, EDSAC loaded its "initial orders" from uniselector switches. By May 1949, these orders evolved into a primitive relocating assembler, leveraging the mnemonic design of instructions. This marked the advent of the world's first assembler, a foundational element of the software industry.

Application Software & Libraries

The development of subroutines was a key focus. By 1951, a substantial library of 87 subroutines was available, covering areas such as floating-point arithmetic, complex numbers, differential equations, trigonometric functions, and matrix operations. This facilitated complex problem-solving for researchers.

Floating-point arithmetic
Complex number operations
Checking routines
Division (via subroutines)
Exponentiation
Function routines
Differential equations
Special functions
Power series
Logarithms
Miscellaneous operations
Print and layout routines
Quadrature (Numerical Integration)
Read (Input) routines
Nth root calculations
Trigonometric functions
Counting operations (simulating loops)
Vector operations
Matrix operations

Early Assembly Languages

EDSAC's assembler inspired several subsequent assembly languages, laying the groundwork for more abstract programming paradigms.

Year	Name	Developer
1951	Regional Assembly Language	Maurice Wilkes
1951	Whirlwind assembler	Charles Adams and Jack Gilmore (MIT)
1951	Rochester assembler	Nat Rochester

Impactful Applications

Scientific Discovery

EDSAC was instrumental in advancing scientific research. It was used by Ronald Fisher to solve differential equations in genetics, marking the first application of a computer to biological research. In 1951, it helped discover a 79-digit prime number, the largest known at the time.

Nobel Laureates

The computational power of EDSAC directly contributed to the work of several Nobel Prize winners. Researchers like John Kendrew and Max Perutz (Chemistry, 1962), Andrew Huxley (Medicine, 1963), and Martin Ryle (Physics, 1974) acknowledged EDSAC's pivotal role in their groundbreaking discoveries.

Mathematical Conjectures

In the early 1960s, Peter Swinnerton-Dyer utilized EDSAC to perform calculations on elliptic curves. These results formed the basis for the renowned Birch and Swinnerton-Dyer conjecture, a problem of immense significance in modern number theory and one of the Millennium Prize Problems.

Early Games

EDSAC also hosted early experiments in computer gaming. In 1952, Sandy Douglas developed "OXO," a graphical version of tic-tac-toe displayed on a cathode-ray tube, potentially the world's first video game. Stanley Gill also created a game involving a "sheep" and gates, controlled via the paper-tape reader's light beam.

Enduring Legacy

Successors and Evolution

EDSAC's influence extended through its successor, EDSAC 2, commissioned in 1958. High-level programming languages like Autocode, an ALGOL-like language, were developed for EDSAC 2. The university's computing trajectory eventually led to the adoption of the Titan computer.

The Replica Project

Recognizing its historical importance, the Computer Conservation Society launched a project to build a working replica of EDSAC at The National Museum of Computing (TNMoC) at Bletchley Park. This ambitious endeavor, led by Andrew Herbert, meticulously reconstructs the original machine's logic and functionality.

Location: The National Museum of Computing (TNMoC), Bletchley Park.
Leadership: Andrew Herbert, a former student of Maurice Wilkes.
Reconstruction: Meticulous rebuilding of logical circuits based on simulators and rediscovered schematics.
Documentation: Released under a Creative Commons license.
Progress: First components switched on in November 2014. The project is open to museum visitors.
Milestones: Original operators visited to assist. Commissioning of the fully operational state was estimated for late 2017, though delays have impacted the final completion date.

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References

Professor David Barron, Emeritus Professor of the University of Southampton at a Cambridge Computer Lab seminar to mark the 60th anniversary 6 May 2009.

Museum switches on historic computer.

A full list of references for this article are available at the EDSAC Wikipedia page

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This page was generated by an Artificial Intelligence and is intended for informational and educational purposes only. The content is derived from publicly available data, primarily the Wikipedia article on EDSAC, and has been refined for clarity and depth.

Historical Accuracy: While efforts have been made to ensure accuracy based on the provided source, historical computing topics can be complex. Information is presented as understood from the source material and may not encompass all nuances or subsequent scholarly interpretations.

No Substitute for Expertise: This content does not constitute professional advice regarding computer science history, engineering, or technology. Always consult primary sources and academic experts for definitive research.

The creators of this page are not responsible for any errors or omissions, or for any actions taken based on the information provided herein.

EDSAC: Architect of the Digital Age

💡 Dive in with Flashcard Learning! 💡

What Was EDSAC? ℹ️

🇬🇧 A British Pioneer

🚀 Second to None

💡 Foundation for Innovation

Genesis and Vision 📜

🧠 The Von Neumann Influence

📐 Wilkes' Microprogramming

🤝 Commercial Partnership

Technical Architecture 💻

⚡ Core Components

💾 Memory and Data Representation

⌨️ Input and Output

⚙️ Instruction Set

Pioneering Software 👨‍💻

📜 System Software

📚 Application Software & Libraries

➡️ Early Assembly Languages

Impactful Applications 🌟

🔬 Scientific Discovery

🏆 Nobel Laureates

📈 Mathematical Conjectures

🎮 Early Games

Enduring Legacy ⏳

➡️ Successors and Evolution

🏛️ The Replica Project

Teacher's Corner 🧑‍🏫

Edit and Print this course in the Wiki2Web Teacher Studio

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References

📜 References

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Disclaimer ⚠️

📜 Important Notice

Dive in with Flashcard Learning!

What Was EDSAC?

A British Pioneer

Second to None

Foundation for Innovation

Genesis and Vision

The Von Neumann Influence

Wilkes' Microprogramming

Commercial Partnership

Technical Architecture

Core Components

Memory and Data Representation

Input and Output

Instruction Set

Pioneering Software

System Software

Application Software & Libraries

Early Assembly Languages

Impactful Applications

Scientific Discovery

Nobel Laureates

Mathematical Conjectures

Early Games

Enduring Legacy

Successors and Evolution

The Replica Project

Teacher's Corner

True or False?

Test Your Knowledge!

Gamer's Corner

Discover other topics to study!

References

Feedback & Support

Disclaimer

Important Notice