# Computer Science XI

## NUMBER SYSTEMS

There are several kinds of data such as, numeric, text, date, graphics, image, audio and video that need to be processed by a computer. The text data usually consist of standard alphabetic, numeric, and special characters. The graphics data consist of still pictures such as drawings and photographs. Any type of sound, including music and voice, is considered as audio data.

Video data consist of motion pictures. The data has to be converted into a format that the computer understands. Data can be classified into two forms, analog data and digital data. Analog data can have any value within a defined range and it is continuous. Sound waves, telephone signals, temperatures and all other signals that are not broken into bits are examples of analog data. Digital data can be represented by a series of binary numbers and it is discrete.

The Arithmetic and Logic Unit (ALU) of the computer performs arithmetic and logical operations on data. Computer arithmetic is commonly performed on two different types of numbers, integer and floating point. As the hardware required for arithmetic is much simpler for integers than floating point numbers, these two types have entirely different representations. An integer is a whole number and the floating-point number has a fractional part. To understand about how computers store data in the memory and how they handle them, one must know about bits and bytes and the number systems.

Bits and bytes are common computer jargons. Both the main memory (Random Access Memory or RAM) and the hard disk capacities are measured in terms of bytes. The hard disk and memory capacity of a computer and other specifications are described in terms of bits and bytes. For instance, a computer may be described as having a 32-bit Pentium processor with 128 Megabytes of RAM and hard disk capacity of 40 Gigabytes.