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Module: Topic: Time
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| bet | 3/4 | | Sana | 19.11.2023 | | Hajmi | 89,94 Kb. | | #101551 |
Bog'liq 2 course reading and writing lesson 450 years of progress
F The first half of the 20th century saw enormous technical developments in three main areas: radio, television, and computers. Radio waves were the first to be explored, and in 1902, Marconi sent the first transatlantic radio signal. The first domestic radio with tuners to listen to different stations appeared only 14 years later, in 1916. Once radio was established, scientists and inventors started investigating the possibility of transmitting pictures. The leap from transmitting sound to broadcasting pictures took place in 1925, when John Logie Baird sent the first experimental television signal. By 1939, regular scheduled television broadcasting had begun.
G Computers were being developed at the same time as TV and radio, and in 1944, computers were put into public service for the first time. The first generation of modern programmed electronic computers were built in 1947 and used Random Access Memory (RAM). This is a 'memory' which allows access to any particular piece of information at almost any time. The smallest of these computers was the size of a family car and could store only about 8,000 words.Since they were so large and stored so little, computers hadto change considerably to become as widespread as televisions and radios had.
Car-sized to pocket-sized computers
H From 1950 on, the development of computers was extremely rapid. In 1958, the integrated circuit or 'chip' was invented and computers started decreasing in size. In 1962, the first computer game, 'Spacewar', was sold, and computers became more popular. ARPANET, the original Internet, was launched in 1969, the first microprocessor was developed in 1971, and in 1981 the IBM PC (personal computer) was unveiled. The PC revolution had begun. Since then, computers have become smaller, faster, and 'smarter', and developed into what many of you use for your studies and entertainment today.
Mobile telephony: the first 25 years
I But how did these technical advances in radio, television, and computing affect telephonic communication? Perhaps surprisingly, it was the work on radio waves that was to have the biggest initial effect on the development of the telephone. The new era of phones worked by using radio waves which transmitted a radio signal to a transmission centre and then to the receiver. As they did not need to be attached to electrical wires, phones could be portable for the first time.
J The first generation (1G) phones were those developed in the 1980s. Much larger and heavier than today's mobile phones, these had a fairly limited lange as the transmission networks were still being established.
K It was with the second generation (2G) phones, developed in the 90s, that the mobile truly entered the digital era. The new protocols of these phones, the rules that organize how devices connect to a network, were transmitted digitalized, and the Short Message Service (SMS) was added. Texting was born.
L The second and a half generation (2.5G) phones worked on the same network protocol as 2G phones, but added Wireless Application Protocol (WAP) and General Packet Radio Service (GPRS). These enabled mobile phones to access certain websites. In addition, some 2.5G phones had coloured screens and cameras.
M However, in 2000 a whole new generation of phones was launched: the third generation (3G). These were based on completely new protocols which enabled high-speed connections. A simple comparison illustrates this: the 2.5G phones on GPRS had an Internet access of 144b (bits) per second, whereas a 3G phone could be as fast as 2Mb (megabits) per second.
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