About Computer Hardware

The first commercially successful personal computer, the Apple II, was introduced in 1977. Since then a lot has changed, but the basics of today's computer hardware remain strikingly similar to personal computers built over 20 years ago.

"Computer hardware" refers to the physical components of a computer, as opposed to the software operating system and programs that run on a computer. The key hardware components are:

• CPU - The Central Processing Unit is the core of your computer. It performs the calculations, allocates memory, and coordinates the activities of all software running on the computer.
• RAM - Random Access Memory is used by the CPU. More RAM means the CPU can handle more tasks at once.
• Hard Drive - The hard drive stores your operating system files, applications, and the files you create with applications.
• CD and DVD Drives - Useful for playback of training videos, data backup, and playing music and movies, these drives are standard on almost all new computers and can be purchased as external devices as well.
• Input Devices - The keyboard and mouse are input devices. They send signals to the CPU, which are then sent to the operating system and applications, telling them what to do.
• Display Devices - The most common display devices are built-in monitors on laptops and all-in-one computers, and external monitors. They receive data from a graphics card, which in turn receives information from the CPU. That information is then shown on the monitor screen.

CPU
 

Almost all Windows-compatible computers contain a CPU from either AMD (K-6, Athlon, Duron) or Intel (Pentium, Celeron), while Macintosh computers contain CPUs manufactured by IBM or Motorola (68040, G3, G4). Most CPU vendors have a budget line, for basic office computers, and a high-end line for graphics workstations, gaming machines, and servers.

Processors are commonly referred to by model and clock speed. Thus "Intel Pentium 4 1.5GHz" is a Pentium 4 CPU, manufactured by Intel, running at 1.5 Gigahertz (a Gigahertz is 1,000 Megahertz). Generally speaking, the higher the clock speed, the faster the CPU.

However, because CPUs have differing architectures, two competing processors with the same clock speed will not necessarily be equal in performance. This is why it is important to compare processor benchmarks, which measure processor performance in real-world tasks.

RAM
 

Adding RAM is one of the least expensive methods of boosting a computer's performance. RAM chips are generally simple to install and can be purchased from a variety of vendors.

Hard Drive
 

Hard drives are available in internal and external configurations. Internal drives are less expensive, but require some computer expertise to install. External drives sit on your desk and connect to the computer via a cable. The portability of external hard drives makes them excellent for use with laptops, while the space-saving nature of internal hard drives can be handy when you don't have extra room on your desk.

Seek time is a measure of how quickly a hard drive can search through stored information and make it available on-screen. Most hard drives have seek times in the range of 8ms to 12ms (lower number is faster).

One important factor in seek time is the RPM speed (revolutions per minute) of the drive. Many drives run at 5400 RPM, while faster 7200 RPM drives are becoming standard.

Throughput is a measure of how much data a drive can access per second. Thus, 34Mb/sec. means a drive can send 34 Megabytes of data to the operating system per second.

Transfer rate often is tied closely to the mechanism by which the hard drive connects to the computer. USB-connected drives usually transfer data at around 15Mb/sec., FireWire-connected drives can transfer data at 50Mb/sec or higher, and IDE (usually used to connect internal hard drives) can reach 100Mb/sec. speeds.

CD and DVD Drives
 

CD drives are cheap and fast, but they do vary in reliability. DVD drives, while newer technology, are dropping in price rapidly and becoming standard equipment on many new computers.

Combination drives can play music CDs, read data CDs, play movies on DVD, read data DVDs, and even record movies to DVD. These drives offer tremendous flexibility, but are more expensive than individual CD or DVD drives.

Input Devices
 

Keyboards are rather straightforward devices, but there are a wide variety of keyboards with various refinements available. The standard mouse also has its own variations, the most common of which are the scroll wheel mouse and trackball mouse. The right combination of keyboard and mouse can make a big difference in overall comfort.

Display Devices
 

The size of a computer screen is generally measured diagonally, from the bottom left corner of the screen to the top right corner of the screen. Screen resolution is an important measure of how many pixels (the tiny dots that make up the image you see on screen) the monitor can display. A monitor with 1200x800 resolution has a larger canvas upon which to display images than a monitor with 800x600 resolution.

Larger resolution also means that individual icons and text will appear smaller, even though there is more space on screen. Note that most monitors allow you to choose a screen resolution that is comfortable for your visual acuity.

Graphics cards are generally not an issue unless you're working with sophisticated 3D software or playing the latest 3D computer games.