There are two fundamentally different types of computers – analog and digital. (Hybrid computers combine elements of both types.)
An analog computer solves problems by using continuously changing data (such as temperature, pressure, or voltage) rather than by means of manipulating binary digits as a digital computer does.
People design analog computers for specialized fields (hydrodynamics, aerodynamics, industrial control, etc.). For example, an automobile speedometer is a mechanical analog computer that measures the rotations per minute of the drive shaft1 and translates that measurement into a display of kilometers (or miles) per hour. Electronic analog computers in chemical plants monitor temperatures, pressures, and flow rates2 of chemicals. Although digital computers have replaced most analog computers, analog computers are still being used for flight control systems in aviation and space vehicles.
Digital computers solve problems by manipulating discrete binary digits. A computer can represent any type of data – from numbers and letters to musical notes and other symbols – in the binary code (i.e, using only the two digits 0 and 1 instead of the ten digits, 0–9, that are usually used in everyday life). This process is called digitization. In computer terms, binary digits are called bits. For example, if a number must have seven digits for its binary representation, we say that it contains seven bits. The term "bit" is an abbreviation for "Binary digIT". An 8-bit string is called a byte.
A desk lamp can serve as an example of the difference between analog and digital. If the lamp has a simple on/off switch, then the lamp system is digital, because the lamp either produces light at a given moment or it does not. If a dimmer3 replaces the on/off switch, then the lamp is analog, because the amount of light can vary continuously from on to off and all intensities in between.
Digital computers are generally more effective than analog computers for three main reasons: they are not as susceptible to signal interference; they can transmit data with more precision; and their coded binary data are easier to store and transfer than are analog signals.
Notes: 1drive shaft – âåäóùèé âàë;
2flow rate – ñêîðîñòü ïîòîêà;
3dimmer – ðåãóëÿòîð ñèëû ñâåòà.