performance monitor software Before we begin our detailed study of the architecture of computer systems, let us briefly review some of the fundamental principles and requirements that guide computer system design and operation. In a simple scenario, you use your laptop or desktop personal computer to word process a document. You probably use a mouse to move around the document and to control the features of the word processor software application, and you use the keyboard to enter and modify the document text data. The word processor application program, together with your document, appears on a screen. Ultimately, you might print the document on a printer. You store the document on a disk or some other storage device.
The fundamentals of a typical computer system are readily exposed in this simple example. Your mouse movements and clicks and your keyboard entry represent input to the system. The computer processes the input and provides output to the screen, and, perhaps, to a printer performance monitor software.
performance monitor software , in turn, sends a Web page file that is interpreted by the browser on your computer and presented on your screen. You are probably already aware that HyperText Transfer Protocol (HTTP) is used as a standard for Web message exchanges. The elements of this example differ only slightly from the first example.
Your command inputs tell a Web browser software application on your computer what processing is to take place; in this case, your desire to access a Web page. The output from your computer is a message to a Web server on the remote computer requesting the data that represents the Web page performance monitor software.
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performance monitor software Your computer receives the data as input from the network; the Web browser processes the data and presents the Web page output on the screen. Figure 1.2 illustrates the layout for this example.
The major differences between this and the first example are the source of the input data and the fact that network connectivity is required between the two computers. Instead of the keyboard
performance monitor software the computer system also provides a storage medium of some sort, usually a hard disk, to store the text for future access. In simplest terms, your computer receives input from you, processes it, and outputs results to the screen. Your input takes the form of commands and data. The commands tell the computer how to process the data. Now consider a second, slightly more complex example. Your task in this example is to access a Web page on the Internet. Again, your input to the computer is via mouse and keyboard. When you type the Web page URL, however, your computer sends a message to another computer that contains Web server software performance monitor software.
input data to be processed by your Web browser comes from a communication channel. (Note that the exact nature of the channel is not important for this discussion.) In both cases, your computer receives data input to process, and control input that determines how the data is to be processed, performs the processing, and provides output
COMPONENTS OF THE COMPUTER SYSTEM
The most visible part of the computer system is obviously the hardware that makes up the System. Consider the computer system upon which you write and execute your programs. You use a keyboard and mouse to provide input of your program text and data, as well as for commands to the computer. A display screen is commonly used to observe output. A printer is frequently available as an alternative output to the screen. These are all physical components.
The amount of primary storage determines the maximum number of instructions and data words that can be loaded into memory from a peripheral device at one time. For example, a computer with 2 gigabytes (GB), actually ,147,483,648 bytes1, of memory
would not be able to execute a program that requires 2.7 GB for its instructions and data unless some means is provided within the computer to load the program in sections as each section of the program is needed
The same is true for secondary storage. Even small personal computers provide hard disks with storage measured in tens or hundreds of gigabytes. The storage of images and video, in particular, requires tremendous amounts of storage capacity. It is not uncommon to see arrays of hard disks, even on some personal computers, providing trillions of bytes (specified as terabytes) of long-term storage