لطفا منتظر باشید ...
Breaking Down Your Computer
No, we don’t want you to break your computer. But we do want to describe the computer subsystems. Computers may seem mysterious when you first use them, but the truth is that they’re not terribly complex. When you break down the parts that make up a PC, you see that each part performs a specific task. The sum of the parts equals a computer. This list outlines the subsystems that comprise a computer:Central processing unit (CPU): The CPU, or microprocessor, is often referred to as the brains of a computer because the CPU controls, in minute detail, everything the computer does. CPUs are controlled by software that is essentially a recipe for doing tasks as simple as detecting keyboard input or as complex as communicating across networks to display pictures in a web browser.The most common CPUs are now Intel Pentiums, which you’re using to run your PC. Generally, the faster the CPU, the faster your computer. CPU speed is measured in megahertz (MHz), which means millions of cycles per second. To perform complex tasks such as sending e-mail, a CPU has to perform many simple tasks, or instructions, in order to complete the larger one. Although the simplest instructions require a single CPU cycle, most require several cycles. However, the MHz measurement is a reasonably good measure of how fast a microprocessor runs.
Hard disks: Hard disks — also referred to as hard drives — store all the permanent information on a computer. Hard disks are metal platters that store bits and bytes in tiny magnetic domains (spots). The disk spins, and a magnetic head that floats on a cushion of air reads and writes from the disk. The spinning disk allows the head to quickly access any location on the disk and also creates the air cushion.
Disk controllers: The disk controller connects the drive to the computer’s microprocessor. Several types of controllers are commonly used: IDE, USB, FireWire, and SCSI. Most PCs come with IDE internal hard drives. However, high-performance computers tend to use SCSI–based drives because they’re faster (and more expensive). IDE controllers can connect as many as four drives.
CD-ROM: CD-ROMs store information like hard drives do, but in optical rather than magnetic form. Most PCs use IDE-based CD-ROMs. SCSI CD-ROMs are faster, just like SCSI hard disks. Because the prices of USB and FireWire CD-ROMS are dropping fast, they’re becoming more common.
RAM, or Random Access Memory: RAM is much faster than hard disks and CD-ROMs. Because RAM is used to store temporary information, programs, data, and other types of information are stored in RAM — it “forgets” everything when power to the computer is turned off. RAM is measured in megabytes (MB). A megabyte is roughly one million bytes.
Mouse: Which type of mouse do you have — bus, PS/2, or serial? How many buttons does it have? If you have a serial mouse, which COM port is it attached to, and which protocol (Microsoft or Logitech) does it use?
Monitor/flat panel display: What are the make and model of the monitor or flat panel display? What are its vertical and horizontal refresh rates? You need this information only if you plan to use the X Window System, the graphical portion of Linux. Monitors and flat panel displays perform exactly the same function, but with different technologies. Monitors are the ubiquitous television-like, glass vacuum tube devices that are heavy and quickly being replaced by flat panel displays. Flat panels use liquid crystal display (LCD) technology, which uses less power and space.
Video card: What are the make and model number of the video card or video chip set, and what is the amount of video RAM?
Network interface card (NIC): If you have a network connection, what are the make and model number of the network interface card?
That’s the rundown of computer subsystems. Each one performs a specific function; buttoned up inside a computer chassis (desktop style or laptop), they work together to create the computer you’re familiar with. The next two sections describe hard drives and memory in more detail.
