Part I
.ENIAC – Size – switches – data entry -what was it used for?
ENIAC, short for Electronic Numerical Integrator And Computer, was the first general-purpose electronic computer. It was the first high-speed Turing-complete, digital computer capable of being reprogrammed to solve a full range of computing problems, though earlier machines had been built with some of these properties Size -It included 17,468 vacuum tubes, 70,000 resistors, 10,000 capacitors, 1,500 relays, and 6,000 manual switches. In addition to numerous electronic components, the size of ENIAC was immense. It weighed 30 tons and covered 1,800 square feet.In one second, ENIAC could execute 5,000 additions, 357 multiplications, and 38 divisions—1,000 times faster than its predecessors.
Vacuum tubes size
First Generation – 1940-1956: Vacuum Tubes
The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions. First generation computers relied on machine language to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts.
Transistors
Transistors replaced vacuum tubes and ushered in the second generation of computers. The transistor was invented in 1947 but did not see widespread use in computers until the late 50s. The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output.
Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.
IC
Third Generation – 1964-1971: Integrated Circuits
The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.
Timex Sinclair
At $99.95, it was the cheapest computer you could buy, and Timex sold over 600,000 of them. It sounded like a great idea, to get a computer for $99.95, but it was probably more trouble than it was worth
