Beginner's Guide to the Personal Computer
If you are a new personal computer, or would like to understand how your PC works, this article is for you! Computers can be intimidating, but they can save us time, make us more productive, and give us new hobbies. The intent of this article is to explain the PC in easy-to-understand terms.
Author: Keynote Support
In this article, we will focus on the desktop computer, but most of the information will still make sense if you own a laptop. To keep it simple, we will define a personal computer as not only the "system unit" that does most of the work, but the other pieces of hardware that are required: the monitor (or video display), keyboard, mouse, and printer.
The monitor is the easiest part of the computer system to understand. It looks like a television screen and its purpose is similar - to provide video output. Whenever you do anything on the PC you will be looking at the monitor. There are 2 types of monitors:
- The CRT (cathode ray tube): This monitor is older technology, inexpensive, and reliable. It is compatible with most PCs. However, it's heavy, bulky, requires a great deal of space (especially depth), and generates a lot of heat. In addition, the CRT gives off radiation, which many think is harmful.
- The Flat Panel monitor: This monitor is sleek, lightweight, fairly expensive, and, because of its shallow depth, can be positioned further back on the desktop. A good flat panel has adjustable height and screen tilt. The image produced is slightly less vivid than a CRT. If you can work it into your budget, buy at least a 19” flat panel monitor when you purchase your computer. If you are replacing a CRT, make sure you get a flat panel that will work with your existing PC.
The System Unit
The system unit consists of a lot of electronic components neatly arranged inside a plastic or metal case that lies on the desktop or sits upright on the floor. Inside the case is a power supply and fans to keep the unit cool. PCs generate a lot of heat when powered on; but even with the fans, care must be taken to always provide adequate air circulation so the components will not overheat.
Inside the system unit is a large circuit board to which all the other components are attached. It's called the "motherboard." The motherboard connects all the components together and helps them talk to each other. Some of these components are the central processing unit (CPU), memory, and the various drives. And all external devices, like the keyboard, are attached to the motherboard. If you look at the back of the System Unit, you will see various ports and plugs with which to attach cables. These ports are either part of the motherboard, or part of a component (like a sound card) that is attached to the motherboard.
The System Unit: CPU, Hard Disk, and Memory
Let's begin by discussing the “big three" components, the CPU, hard disk, and memory. To help you understand them, I’m going to create an analogy between these components and YOU working in your office.
Central Processing Unit
The CPU is the “brains” of a computer. It performs all of the required calculations and coordinates the activity of the other components. The CPU is housed on a "microchip" - a very small wafer packed with electronic circuits. Using our analogy, the CPU is like your brain. Your brain controls your calculations and coordinates the rest of your body.
Hard Disk or Hard Drive
The hard disk is where data is permanently stored. Using our analogy, the hard disk is like the filing cabinet in your office. The hard disk consists of platters and various mechanics and electronics. Often a PC's hard drive is called the "C drive." (All the drives in a PC have a letter assigned to them.) In your filing cabinet are individual papers inside of folders. And you may have folders inside of folders. This is how the hard disk is structured. The smallest “piece of paper” the hard disk recognizes is a “file” - like a Word document or a photograph. The hard disk stores these files in folders, and often has folders inside of folders. So, the PC’s hard drive is like your filing cabinet. There are basically 3 kinds of data that the PC stores on the hard disk. They are:
- The Operating System (OS): The OS is a large program that operates the actual PC hardware - the most popular being Microsoft Windows. Without an OS, your PC is a useless pile of metal. The OS 'talks' to the hardware and interfaces between it, the user, and the application programs (see below). It receives input from the keyboard and mouse, sends information to the monitor, controls data going in and out of the CPU, and keeps track of files and folders on the hard disk. Typically when you buy a PC the OS is already loaded, or installed, on the hard disk and ready to run when you press the power button.
- Application software: If the OS allows the PC to work, application programs allow YOU to work! An application is a software program, running underneath the Operating System (OS) and performs a specific function - like word-processing, creating spreadsheets, or manipulating photos. You may opt to purchase your PC with some application software already on the hard disk, or you can buy it separately. Most purchased software comes on a CD. Some application software can be downloaded for free, or for a minimal charge, from the Internet.
- User Data: the other information that is permanently stored on the hard drive is the data YOU create; i.e. letters or publications, spreadsheets, and photos you've loaded in from your digital camera.
Memory is the place that the CPU temporarily puts the data it is currently working on. In fact, the central processing unit (CPU) cannot do anything with your data unless that data is first loaded into memory. Using our analogy, you won't get any work done while the data you need sits in the file cabinet. You must temporarily remove the file from your file cabinet and place it in front of you on your desk (memory) in order to work on it. Memory consists of many circuits residing on microchips. The more memory you have, the more programs you can have running at the same time and the faster your PC will run. (The larger the top of your desk is, the more data you can retrieve from your file cabinet and the more items you can be working on at the same time.) Also, when your PC is running, key portions of the Operating System itself have to reside in memory.
The System Unit - Other Disk Drives: Diskette, CD, and DVD
Now let's talk about drives that read and write to media (i.e. CDs) that is removable. You need these drives for several reasons: to install software, to play CDs or DVDs, to backup your data, to copy files for someone else, or to create a music CD. We will discuss 3 other drives: the diskette drive, the CD drive, and the DVD drive. All 3 attach to the motherboard inside the system unit and you access them from the front of the case. Before you buy a PC, sit down with an expert and discuss what you will be using your PC for so that you can determine your PC's required features.
- CD drive: CD stands for compact disc. Your CD drive will either just read CDs, or read and write to CDs. When data is written to a CD, a laser “burns” the data onto its surface. The CD drive is often the "D" drive.
- DVD drive: DVD stands for digital video disc. A DVD looks like a CD, but it holds a lot more data and the recording format is different. New PCs usually come with a DVD reader. You can opt for a DVD drive that reads and writes. I recommend upgrading your DVD drive to a “burner” if you have large amounts of data (photos, perhaps) to backup on a regular basis. The DVD drive is often the "E" drive.
- Diskette Drive: Few PCs have diskette drives as diskettes are seldom used as they hold so little data compared to other media. However, if you have an older computer, let's review. The diskette drive is always called the "A drive." A diskette is a 3 ½” square disc. If you have a lot of data stored on diskettes, you can request that a diskette drive be installed in a new PC, or you can buy an external diskette drive. NOTE: If you have a diskette in the drive when powering up a PC, you'll get the error message “non-system disk or disk error." Just remove the diskette from the drive and press any key on the keyboard to resume.
The System Unit - Other Components
Lastly, there are some other important components inside the system unit that control peripheral devices or external devices such as printers, scanners, and modems. These internal components all have external ports on the back of the system unit by which you attach these peripheral devices via cables.
- The modem and/or Ethernet network card: The Ethernet card and modem are used to establish a home network and to attach the PC to the internet via a broadband connection, such as DSL or cable. To access the internet via dial-up, the phone line cord plugs into a modem port on the back of the system unit to use the internal modem. External modems are also available.
- Also inside the system unit and attached to the mother board are the electronics that control other peripherals, such as the monitor, mouse, keyboard, speakers, and printers. If you look at the back panel of the system unit, you'll see a myriad of ports and connectors in which to attach these peripherals.
Let's quickly review! The monitor is like a TV and is where the video output is displayed. There are two types of monitors: CRTs and flat panel. The system unit houses the PC's internal components that are attached to, and managed by, the motherboard (large circuit board). The three largest components of the system unit are: the CPU (your brain), the hard disk (filing cabinet), and memory (working area on your desk). Three kinds of information are stored on the hard disk: the operating system (OS), application software, and your data. And we know the PC hardware is useless without the OS. In addition, there are other useful drives inside the system unit that read and write to removable media (diskettes, CDs, and DVDs).
Peripherals: External Devices Attached to the System Unit
Now let's talk about peripherals. A peripheral is an “external” device attached to the PC: monitor, keyboard, mouse, printer, scanner, etc. As mentioned above, though they are external devices, there are still attached to the mother board and the mother board manages them. Let's go into a bit more detail.
- Monitor: To get a warm and fuzzy start, we began this article talking about the monitor - the video output of our PC. One side of the video card attaches to the mother board so that the operating system can control the monitor. The other side of the video card has a port - visible on the back of the system unit - into which the monitor cable is attached. If you use a PC to do a lot of graphics or play video games, you need a powerful video card. For most folks, a modest video card will suffice.
- Speakers: Most PCs come with speakers and the speakers are controlled by a sound card. The sound card is attached to the motherboard and also has ports on the back of the system unit by which you attach the cords for the speakers and perhaps a microphone. Sound cards also vary in power and price.
- Keyboard and mouse: We use these devices to enter data into to the PC. The motherboard has the necessary controllers to manage your keyboard and mouse. On the back panel you'll see round ports for attaching these devices. However, many keyboards and mice can be attached to the PC via a "USB port." (See below).
- Printers and Scanners: In the old days, printers were attached to a connector with many pins located on the back panel (called the parallel port). Today, most printers are attached via a USB port, as are scanners. So let’s talk about USB!
USB Ports and the Devices That Use Them
USB (Universal Serial Bus) is a popular technology for transferring data to and from digital devices, and many peripherals (external devices) attach to the System Unit via a USB port. If you are buying a new PC, make sure it comes with an adequate number of USB ports and make sure a few ports are located on the front of the system unit for easy access. Some of the devices that connect via a USB port are printers, scanners, digital cameras, video cameras, mice, keyboards, external disk drives, and flash drives.
A very popular device that connects to a USB port is the flash drive, or memory stick. It is a small device about 2” x ¾” that plugs directly into a USB port and is used to store data. Flash drives are inexpensive and can hold gigabytes of data. There are useful for backing up large files and transporting files between PCs. Because of USB technology, external disk drives are also popular. They are much larger than a flash drive but can hold more data. They vary in size, capacity, and price, but the attach via a short cable to a USB port.
How Storage is Measured
Computers talk in “bits” and eight bits equals one “byte.” And 1,024 bytes equal 1 kilobyte (KB). We seldom talk in bytes or KB these days; we talk in bigger numbers.
- 1,024 kilobytes (KB) = 1 megabyte (MB)
- 1,024 megabytes (MB) = 1 gigabyte (GB)
- 1,024 gigabytes (GB) = 1 Terabyte
Let’s put this information to practical use. Here are the capacities today of the various media we’ve discussed: A diskette holds 1.44MB. A CD holds 700MB. A DVD holds 4.7GB. The size of the average photo on an older camera is about 1MB. And a two-page letter in Microsoft Word is about 25KB. A CD can hold about 700 photos, or over 28,000 two-page letters. And a DVD can hold over 4,000 photos! If your photos average 2MB in size, reduce that to more than 2,000 photos.
You know, in many ways YOU are just like a PC. Your brain is a Central Processing Unit. Your long-term memory (file cabinet) is like the hard disk where data is permanently stored, and your short-term memory (working area) is like the PC's memory. And all of them work together to control your eyes, ears, fingers, toes and to produce work! I hope you now have a much clearer picture of what a PC is all about. Please see my other articles that will help you use your PC!
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