Historical Overview of The Development of the Computer

There are two historical processes the drove the development of the computer.
  1. a need for data processing - a result of the industrial revolution and the growth of government sponsored social programs
  2. scientific need for computing
Web Sites in Computing History is a collection of web sites from various sources including links to the IEEE Annals of the History of Computing and web sites for famous historical computers.

Early Milestones in the History of Computing
  1. early mechanical aids: abacus and counting boards
  2. logarithms - discovered/invented by John Napier (1550 - 1617) and developed by Henry Briggs (1561-1630) and others
  3. Blaise Pascal (1623 - 1662) - invented an early mechanical calculator, the "Pascaline" that could add and subtract.
  4. Gottfied Wilhelm Leibniz (1646 - 1716) invented the "Step Reckoner" which could do all four arithmetic functions. Its design was the basis for many subsequent mechanical calculators.
  5. Charles Babbage (1791 - 1876) - inventor of the Difference Engine I, the Difference Engine II, and the Analytic Engine. None were ever completed. The Analytic Engine with its "store" and "mill" makes it appear very much link a modern computer. Ada Byron, Countess of Lovelace, in writing about the Babbage's Analytic Engine wrote about how it could be programmed. For this she has been called the world's first programmer 
  6. Hermann Hollerith (1860 - 1929) - Inventor of punch card data processing equipment. The company he found merged with three others ; eventually it became IBM.  See From the U.S. Constitution to IBM
The late 1930's and 1940's. During the period leading up to WWII and after, a number of people independently worked on building calculators
  1. John Atanasoff at Iowa State with Clifford Berry, a grad student, build the Atanasoff-Berry-Computer, a special purpose calculator to solve systems of linear equations.  The ABC used a rotating drum memory to store binary numbers.
  2. Conrad Zuse in Germany built a series of four electro-mechanical calculators called the Z1, Z2, Z3, and Z4. 
  3. Howard Aiken at Harvard University with funding from IBM and support from the US Navy build the electromechanical Automatic Sequence Controlled Calculator (ASCC) also known as the Harvard Mk 1.(1944). He later went on are designed 3 more machines (Mk 2 through Mk 4). In 1948 IBM build their own, the Selective Sequence Electronic Calculator (SSEC).
  4. Bletchley Park in England was home to the British super-secret Government Code and Cipher School, the famous site where many of Germany's secret codes were decrypted. The Colossus (1944) was an electronic computer specially build to crack the German Geheimschriber codes.  
  5. The ENIAC, Electronic Numerical Integrator and Computer, was a war-time project funded by the US Army at the Moore School of Engineering at the University of Pennsylvania  in Philadelphia .The brainchild of John Mauchly and J. Presper Eckert, the ENIAC was the first general purpose electronic calculator. It became operational in 1946.
Because the ENIAC was electronic and therefore very fast, it had the greatest impact on subsequent computer development. (The Colossus was also electronic but because it was a secret project, its existence was unknown until much later). While working on the ENIAC, Eckert, Mauchly and John von Neumann (who later joined the project) came up with the design for a stored program computer, one in which the memory was big enough to store both numbers (data) and instructions. Two critical papers were written and circulated by von Neumann and others laid out the logical design of the stored program computer

  1. First Draft of a Report on the EDVAC (1945) J. von Neumann laid of the design of a stored program computer called the EDVAC, the Electronic Discrete Variable Automatic Computer. This was a serial design based on delay-line memory. 
  2. "Preliminary discussion of the logical design of an electronic computing instrument" (1946) by A. Burks, H. Goldstine and J. von Neumann presented a parallel design based on CRT memory. The parallel memory access design was the one used today.
After the end of WWII in the summer of 1946, based on their experiences with the ENIAC the Moore School in Philadelphia held a summer workshop on the design of electronic computer which were attended by a number of British mathematicians, scientists and engineers. Also while the existence of the Colossus project was shrouded in post-war secrecy, the experience  gained by British scientists and engineers in the design of complex electronic computing devices was still available. Hence the first working stored program computer were built by the British.
 

The early computers above were actually sequentially controlled calculators. With very limited memory only data could be stored. There was no room for code. Program control was accomplished by using paper tape (Zuse's Z1 - Z4, ASCC, SSEC) or by re-wiring the computer (ENIAC). Once technologies were developed (e.g. Williams tube/Selectron memory, acoustic delay line, magnetic drum, ferrite "core" memory) that allowed larger memories, stored program computers could be build, machines with enough memory to store both data and code. These were the first true computers.


Some Famous Early Computers

  1. Manchester SSEM (Small Scale Electronic Machine) - also called the Manchester Mark I - "Baby" (1948) - Built at the University of Manchester, England, this small prototype (32 words of 32 bits - 7 instructions) executed the first program to run on a stored program computer (June 21, 1948). This machine evolved into the Manchester Mark I (a 40 bit machine with more memory and more instructions), a commercial version of which was produced by Ferranti. 
  2. Cambridge EDSAC, Electronic Delay Storage  Automatic Computer (1949) built at Cambridge, England, this was the first operational computer. Maurice Wilkes (famous for micro-code) headed up the project
  3. MIT Whirlwind (ca 1950): It started out as an aircraft simulator and ended up as a very fast 16 bit computer that specialized in "real-time" computing.
  4. Univac-1 (1951): First commercially available computer in the US. After the ENIAC, Eckert and Mauchly formed a company (Eckert Mauchly Computer Corporation) to product this EDVAC-like machine (EMCC was later bought out by Remington Rand which later became Sperry Rand). 
  5. IAS - Institute of Advanced Study computer - the result of the 1946 "Preliminary discussion ..." by Burks, Goldstine & von Neumann. Unlike the EDVAC-like machines this design of this machine was parallel which mean that its 40 bit words were processed in parallel instead of serially.  The design of the IAS computer influenced many subsequent machines. Today parts of it are on display in the Smithsonian. 
  6. EDVAC (1952) - finally! 
  7. IBM 701 (1952) - IBM finally enters the market with its first scientific computer
Memory Technologies: For early computers, memory was small, expensive and not always reliable! It's only with the fairly recent development of VLSI technology (memory chips) that the "memory" problem was solved. Below are listed some of the early memory technologies  
  1. Vacuum Tubes: fast but bulky and too expensive to be  practical for anything internal registers
  2. Acoustic delay lines: bits were stored as sound waves that propagated down a meter length tube of mercury. When the waves reached the far end they were converted to electronic pulses, amplified and re-sent as sound waves at the near end. The "feedback loop" worked because sound waves propagate much slower thane electricity so approximately 1000 bits could be stored as acoustic waves in a column of mercury.  
  3. CRT memory - Williams Tube/Selectron - information stored as a charge on the face of a cathrode ray tube
  4. Magnetic drum - essentially a fast spinning magnetic drum with information stored as magnetic "pulses" in parallel tracks each with its own r/w head .The time to access information was limited by the time it took the drum to rotate so the required information was under the r/w head (rotational latency). Slow memory but cheap. The IBM 650 used this form of storage.
  5. Ferrite Core - This is the first technology that really worked. The polarity of a magnetic field of a small ferrite ring was used to store a 0 or 1.
  6. Transistors/Integrated Circuits - what we have today

Additional information about many of these early computers - and a few more - can be found at my Web Sites in Computing History, which includes links to web sites of historical computers.


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