Hardware: The CPU & Storage

How to choose Multimedia system?

You’re in the market for a new PC and are studying the ads. What does “1 GB DDR SDRAM” mean? How about “160 GB SATA 7200 RPM Hard Drive”? Let’s see how to interpret a typical computer ad. (• See Panel 4.4.) Most desktop computers are multimedia computers, with sound and graphics capability. As we explained in Chapter 1, the word multimedia means “combination of media”—the combination of pictures, video, animation, and sound in addition to text. A multimedia computer features such equipment as a fast processor, DVD drive, sound card, graphics card, and speakers; and you may also wish to have headphones and a microphone. (Common peripherals are printer, scanner, sound recorder, and digital camera.) Let us now go through the parts of a computer system so that you can understand what you’re doing when you buy a new computer. First we look at how the system processes data. In the remainder of this chapter, we will consider the system unit and storage devices.

Components of a Computer

The five classic components of a computer are briefly described below. Each component is discussed in more detail in its own section. The operation of the processor is best understood in terms of these components.

Datapath - manipulates the data coming through the processor. It also provides a small amount of temporary data storage.

Control - generates control signals that direct the operation of memory and the datapath.

Memory - holds instructions and most of the data for currently executing programs. Input - external devices such as keyboards, mice, disks, and networks that provide

input to the processor. Output - external devices such as displays, printers, disks, and networks that receive

data from the processor.

Virtual memory is a technique that allows the execution of processes which are not completely available in memory. The main visible advantage of this scheme is that programs can be larger than physical memory. Virtual memory is the separation of user logical memory from physical memory.

Process is the program in execution:The notion of process that is central to the understanding of today’s multi-user computer systems. Several of the more popular definitions are presented, but no perfect definition of process has as yet appeared in the literature.The definitions and concepts introduced here serve as a basis for the discussions of concurrent processes and process scheduling.

RUNNING NOT RUNNING

EXITENTER

DISPATCH

PAUSESTATE TRANSITION

PROCESS STATES

TWO STATE PROCESS MODEL