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Diff — EDSAC

Comparing rev 3 → rev 4

	EDSAC — the Electronic Delay Storage Automatic Calculator — was the computer built by Maurice Wilkes at the University of Cambridge that ran its first programs in May 1949. It was not the first stored-program machine to switch on — the [[Manchester Baby]] beat it by eleven months — but it was the first to run a useful computing service: real users submitting real problems and getting real answers.

	# Origin

	Wilkes visited the United States in 1946, saw the ENIAC work and attended the Moore School lectures on electronic computer design — where the [[EDVAC report\|EDVAC ideas]] were presented. He came back to Cambridge determined to build a practical machine. EDSAC was designed in early 1947 and, unlike the Baby, built for daily use from the start: 3,000 vacuum tubes, mercury delay-line memory, paper tape input, teleprinter output.

	The machine ran its first program — a routine to print a table of squares — on 6 May 1949. By the end of the month it was doing regular work for Cambridge's mathematics and physics groups.

	# Why it matters more than the race

	The Baby was a proof-of-concept; EDSAC was a computer. What Wilkes's team built on top of the hardware became the foundation of programming practice:

	- A subroutine library — EDSAC's programmers wrote reusable punched-tape routines (sine, square root, division…) and kept them in a cabinet; users copied them into their programs. The first software library — and the first place the word "library" means code.
	- Assembler-style notation — Wilkes's team wrote programs in a mnemonic "initial orders" notation that was translated by the machine, the earliest working assembly system.
	- The first software book — Wilkes, Wheeler, and Gill's Preparation of Programs for an Electronic Digital Computer (1951) — the first textbook on programming, for decades just called "Wilkes, Wheeler, and Gill."
	- Debugging in the wild — Wilkes famously wrote: "the realisation came over me with full force that a good part of the remainder of my life was going to be spent in finding errors in my own programs." The first programmer to discover debugging was real.

	# Legacy

	- EDSAC 2 followed in 1958; Wilkes built microprogramming (the idea that a CPU's control logic is itself a program) into it — a design technique still at the heart of processors.
	- Cambridge's computing culture fed directly into the British software industry: EDSAC alumni founded or seeded companies and labs across the country.
	- Wilkes won the Turing Award in 1967, the second ever given.

	# See also

	- [[Manchester Baby]]
	- [[EDVAC report]]
	- [[John von Neumann]]
	- [[The first programmers]]
	- [[History of Programming]]

	# References

-	1. Lavington, Simon. Early British Computers (Manchester UP, 1980).
-	2. Wilkes, Maurice V. Memoirs of a Computer Pioneer (MIT Press, 1985).
+	1. Lavington, Simon. [Early British Computers](https://manchesteruniversitypress.co.uk/9780719008052/) (Manchester UP, 1980).
+	2. Wilkes, Maurice V. [Memoirs of a Computer Pioneer](https://mitpress.mit.edu/9780262231229/memoirs-of-a-computer-pioneer/) (MIT Press, 1985).
	3. Lavington, Simon. A History of Manchester Computers (NCC Publications, 1975; 2nd ed. 1998).

	[[Category:History]]
	[[Category:Hardware]]

	EDSAC — the Electronic Delay Storage Automatic Calculator — was the computer built by Maurice Wilkes at the University of Cambridge that ran its first programs in May 1949. It was not the first stored-program machine to switch on — the [[Manchester Baby]] beat it by eleven months — but it was the first to run a useful computing service: real users submitting real problems and getting real answers.

	# Origin

	Wilkes visited the United States in 1946, saw the ENIAC work and attended the Moore School lectures on electronic computer design — where the [[EDVAC report\|EDVAC ideas]] were presented. He came back to Cambridge determined to build a practical machine. EDSAC was designed in early 1947 and, unlike the Baby, built for daily use from the start: 3,000 vacuum tubes, mercury delay-line memory, paper tape input, teleprinter output.

	The machine ran its first program — a routine to print a table of squares — on 6 May 1949. By the end of the month it was doing regular work for Cambridge's mathematics and physics groups.

	# Why it matters more than the race

	The Baby was a proof-of-concept; EDSAC was a computer. What Wilkes's team built on top of the hardware became the foundation of programming practice:

	- A subroutine library — EDSAC's programmers wrote reusable punched-tape routines (sine, square root, division…) and kept them in a cabinet; users copied them into their programs. The first software library — and the first place the word "library" means code.
	- Assembler-style notation — Wilkes's team wrote programs in a mnemonic "initial orders" notation that was translated by the machine, the earliest working assembly system.
	- The first software book — Wilkes, Wheeler, and Gill's Preparation of Programs for an Electronic Digital Computer (1951) — the first textbook on programming, for decades just called "Wilkes, Wheeler, and Gill."
	- Debugging in the wild — Wilkes famously wrote: "the realisation came over me with full force that a good part of the remainder of my life was going to be spent in finding errors in my own programs." The first programmer to discover debugging was real.

	# Legacy

	- EDSAC 2 followed in 1958; Wilkes built microprogramming (the idea that a CPU's control logic is itself a program) into it — a design technique still at the heart of processors.
	- Cambridge's computing culture fed directly into the British software industry: EDSAC alumni founded or seeded companies and labs across the country.
	- Wilkes won the Turing Award in 1967, the second ever given.

	# See also

	- [[Manchester Baby]]
	- [[EDVAC report]]
	- [[John von Neumann]]
	- [[The first programmers]]
	- [[History of Programming]]

	# References

-	1. Lavington, Simon. Early British Computers (Manchester UP, 1980).
-	2. Wilkes, Maurice V. Memoirs of a Computer Pioneer (MIT Press, 1985).
+	1. Lavington, Simon. [Early British Computers](https://manchesteruniversitypress.co.uk/9780719008052/) (Manchester UP, 1980).
+	2. Wilkes, Maurice V. [Memoirs of a Computer Pioneer](https://mitpress.mit.edu/9780262231229/memoirs-of-a-computer-pioneer/) (MIT Press, 1985).
	3. Lavington, Simon. A History of Manchester Computers (NCC Publications, 1975; 2nd ed. 1998).

	[[Category:History]]
	[[Category:Hardware]]