MODEMS
A modem (modulate demodulate) is a network device that both modulates and demodulates analog carrier signals (called sine waves) for encoding and decoding digital information for processing (Janssen C 2014). The most common use of modems is both for sending and receiving digital information between personal computers and for connecting to the internet. Modem is considered as an important hardware of computer and most computers in the past came with a built in modem, but now many manufacturers are not including it because of the increased popularity of broadband connections. This essay will concisely discuss the history of the modem and highlight the key developments of this technology. It will also throw light on the factors that influenced this technology and outline its current features.
Modems originated as a way for teletype machines to communicate over ordinary telephone lines (Edwards 2014). When the US Air Force needed a convenient way of transmitting hundreds of radar images to command centers during the Cold War in the end of 1940s, they turned to the telephone system and modems as a solution (Dalakov 2014). Thus, first digital modem was developed in 1950s. In 1962, the first commercial modem was manufactured – the Bell 103 by AT&T. The Bell 103 was also the first modem with full- duplex transmission, frequency-shift keying, and had a speed of 300 bits per second (Wright 2014). For many years, AT&T hold a monopoly on the phone system in the United States, so only AT&T could provide modems to work on its network (Edwards 2014). Companies got around this restriction by inventing the acoustic coupler, which hooked a radio or modem to the telephone system via a cradle in which the user placed a standard phone handset. This way, the modem could be acoustically but not electronically linked (Edwards 2014).
Then in 1977, Dale Heatherington and Dennis Hayes created the world's first PC modem, the 80-103A, for S-100 bus computers (Edwards 2014). A modem that offered all the right features at exactly the right price point and connected directly to the phone, something that users had not had the luxury of experiencing until this point. Hayes was a computer hobbyist, and felt that modems would be highly compelling to users of what would soon be known as home computers (Wikipedia 2014). The main problem with producing such a modem was forwarding commands from the computer. This was addressed in internal modems that plugged directly into the computer's motherboard. This was a straightforward and thus a popular solution; the Novation APPLE-CAT II for the Apple II computer was an early programmable modem of this type (Wikipedia 2014). It was so successful that they started up DC Hayes Associates. In 1981, D.C. Hayes Associates introduced its seminal Hayes Stack Smartmodem. The 300-baud (a unit used to express the speed of transmission of electronic signals) modem was the first to integrate its own industry standard set of commands (Edwards 2014). Using a series of ASCII strings users could initialize, autodial, answer, hang up, and more. Modems for early personal computers of 1980s were a mix of direct-connect and acoustic models. Some were “smart” copying the Hayes command set whereas others were dumb clones of the Bell 103A standard requiring manual dialing (Edwards 2014). The highest modem speed of the time was 1200 bps.
From mid 1980s onwards, IBM PC clones dominated the PC market, leading to a new era of internal ISA modem cards designed for PC compatibles (Edwards 2014). Telebit introduced its Trailblazer modem in 1984 which supported a feature that allowed modems to copy the UCCP g protocol, commonly used on UNIX systems to send e-mail (Wikipedia 2014). Around this time speedy 2400 bps modems emerged in the market. Advancement in technology further increased this limit over years; first to 4800 bps, and then to 9600, 14400, 28800, 33600, and