Computers - From steam power to quantum tunneling in 150 years - Evolution

A history and description of computers is immediately faced with a task of determining what truly constitutes a computer. A basic definition from typical web sources spits out:

com.put.er Pronunciation Key (km-pytr) n.

1. A device that computes, especially a programmable electronic machine that performs high-speed mathematical or logical operations or that assembles, stores, correlates, or otherwise processes information.
2. One who computes.

This node concerns itself with definition 1, a broad category of machinery: mechanical, electrical, whatever. While most modern computers are purely electrical devices, the history of computers is steeped in mechanical
contraptions of ever-increasing complexity. A full history would be excessive here, and is well documented in many places over the web. A brief synopsis, therefore, of that long history is presented here:

1. ~3000 BCE: The abacus is invented, apparently in Babylonia. Simple to construct, but allows addition and multiplication to be done with relatively high speed.

2. 1623 CE: William Schickard develops a calculation clock to help with multiplying large numbers, the first true mechanical calculating machine. No copies of the machine remain today.
3. 1801 CE: Joseph-Marie Jacquard constructs an automatic loom, using punch cards (making them the longest enduring computer data storage format), a precursor to today's robotic assembly lines. The loom could create intricate woven patterns based on sequences of punch cards. Riots later erupt over such machinery, blamed for replacing people with machines.
4. 1823 CE: Charles Babbage is given a grant by the English government to develop a full Difference Engine, a steam-powered polynomial evaluator. Babbage planned to use the Engine to recalculate critical mathematical and navigational tables. Ada Byron, Countess of Lovelace, corresponded with Babbage over the design constantly. Ten years later, Babbage conceived of the Analytic Engine, a true modern computer.
It was to have a memory store, an execution unit, and it would operate on a formula (in modern usage, computer programs), and it would be able to calculate any expression. Countess Lovelace documented the design throughly, and became the first known programmer when she developed formulas for the planned machine.
Unfortunately, the design was far too ambitious for the technology of the era, and an Analytic Engine was never built. In the end, neither was the Difference Engine, the half-built machine now residing in the Science Museum in London.
Babbage is considered to be the inventor, if not the implementor, of the true computer.
5. 1854 CE: George Boole publishes "An Investigation of the Laws of Thought", developing Boolean logic, a system of logical algebra. Boole created the algebra to evaluate the truth of logical propositions; his system is now the basis of every digital computer.
6. 1939-1944 CE: Konrad Zuse, a German engineer, completes the Z2, a machine using electromechanical relays and boolean logic, but otherwise very similar in basic design to Babbage's Analytic Engine. Conscripted into the army, he lead a team in designing the Z3, which had a 64-number memory, which each number being 22 binary digits (bits) long. The machine could perform a multiplication in 5 seconds. The Z3 was finished in 1941,
and was the first-ever working general purpose programmable computer. Unfortunately, it was destroyed in an air raid in Berlin in 1945. Meanwhile, research in the United States followed similar lines: Howard Aiken constructed the Mark 1, using electromechanical relays, with speeds similar to the Z machines. John Atanasoff and Clifford Berry designed, and partially constructed a fully electronic machine based on eletronic valves,
but the Atanasoff-Berry Computer (or ABC) was never completed.
7. 1943 CE: The Colossus is constructed to help break the German Enigma code. Built by a group in Bletchley Park, England which included Alan Turing who became one of the pioneers of Computer Science, the Colossus can be considered the first completely electronic computer, even though it could only perform the specialized task of breaking Enigma codes.
8. 1944 CE: The ENIAC is completed under a U.S. Government grant. Designed by J. Presper Eckert and John Mauchly, it was the first working fully electronic general-purpose computer. It was also quite large, measuring 100 by 10 by 3 feet, and weighed roughly 30 tons. It could perform a multiplication in less than 3 microseconds.
9. 1954 CE: The TRADIC becomes the first computer to use transistors as a replacement for the valves, setting the stage for the rapid growth in computer complexity predicted by Moore's Law