The Architecture of Computer Hardware, Systems Software, & Networking: An Information Technology Approach, 5th Edition

PART TWO

DATA IN THE COMPUTER

You are probably aware that all data in computers and other digital devices is stored in the form of binary numbers, using only 1s and 0s. The situation is more complicated than this, however, because those binary numbers represent both program instructions and data, and they may represent the data in many different forms. Programming languages such as Java, for example, allow a programmer to specify data in primitive form as integer numbers, real numbers, characters, or Booleans. In addition, the files on your computer undoubtedly include representations of graphical images, sounds, photo images and video, and who knows what all else!

Each of the myriad different data types and objects uses its own format or formats for storage in the computer. Manipulating data requires keeping track of which format is in use for a particular set of data. Each numerical data format requires a different method for doing arithmetic calculations, and there are a number of different formats for representations of images and the like with different capabilities and manipulation requirements, which complicates data handling even further. Naturally, the computer must be able to perform format conversions between equivalent but different types. Most of this data-type record keeping must be handled within programs; to the computer, the bits all look the same. Only the programs know what the bits actually represent.

Each data type and format has its own uses, advantages, and ...