In the last section, we talked about the Colossus computer, the one invented by Turing and Tommy Flowers to help end World War Two. Thing is, if you looked at it, you probably wouldn't recognise it as a computer in the modern sense.
Colossus was big. Really big. It was seven feet tall, seventeen feet wide, and eleven feet deep, resulting in a total of 1300 cubic feet - about the size of a living room. It weighed five tonnes - that's more than the weight of two Range Rovers! Its 2500 valves, 100 logic gates, 1000 resistors and seven kilometres of wiring required eight kilowatts of power. By comparison, your school laptop, designed just 75 years later uses about twelve watts. That's an improvement of a factor of 650!
Of course, Colossus was still a partially mechanical machine. The first fully electronic computer, ENIAC, was built in 1945 and put to work in 1946, it was designed for the US Army to calculate artillery firing tables, although it was also used to determine the viability of thermonuclear bombs! Due to being purely electronic, it could calculate a thousand times faster than electro-mechanical computers. It could calculate a trajectory that would take a human 20 hours in 30 seconds, making it 2400 times more efficient than a human for that particular job.
It cost half a million US dollars to build - about $6.3 million in today's money. Even a seriously beefy gaming PC like an Alienware Aurora R7 clocks in at a mere $1,200 - over 5000 times cheaper. The ENIAC also ran at only 100 kHz. By comparison, the Alienware's 4 gHz processing speed makes it 40,000 times faster. That's a cost-to-performance improvement ratio of 20 million!
At this point, computers didn't have what we would recognise today as RAM - random-access memory. The first computer with RAM was the Manchester Baby, an experimental computer that paved the way for the first-ever commercially available computers. The Baby had one kilobit of RAM (one-eighth of a kilobyte). The eight gigabytes of RAM in the modern Alienware computer I was comparing the ENIAC to are an improvement by a factor of sixty-four million.
in the early days, you couldn't actually buy a computer. They were exclusively for use by governments and whoever else could afford to build one - which, with how expensive they were, wasn't many people. The first commercial computers, the British Ferranti Mark 1 and the American UNIVAC, were put on sale in 1951. They were very expensive - UNIVAC prices rose and rose to over a million dollars as more were sold, and only very rich companies like General Electric, Du Pont and Westinghouse could afford them. Most were sold to branches of the US government, with the most famous being the one purchased by the US Census Bureau.
This computer was used by the Census Bureau in conjunction with the television broadcaster CBS, to predict the results of the 1952 US presidential election. Using a sample of just 1% of the voting population, it famously - and correctly - predicted that Republican candidate Dwight D. Eisenhower would win by a landslide. This event brought computers into the public eye in America, and furthered interest and development of computing technology.
The final evolutionary link between the hulking beasts of yesteryear and the slick, modern machines of today is the mainframe. These were massive, powerful computers that were designed to be used by businesses. IBM were the masters of these machines, and one of their most important inventions in this field was something called System360, a family of computers large and small (relatively, of course) that used the same set of instructions on how to operate. This allowed a company that bought a lower-end System360 computer to upgrade to a better one without having to rewrite all their code.