CPU stands for central processing unit. This chip inside the computer can add, subtract, multiply, and divide. This chip is usually denoted by a number. The numbers in use today on CPUs are (from slowest to fastest):

286,

386,

486,

Pentium

The higher the number, the faster the machine can process data. For example, a 486 is faster than a 386 and a 286. The Pentium is the only difference to this rule. The Pentium is faster than a 486, 386, and a 286.

After these numbers, a SX, DX, DX2, DX4 (ordered from slowest to fastest) often follow. This is also another measure of how fast the CPU can process data. For example, a 386SX is generally slower than a 386DX, a 486DX2 is generally slower than a 486DX4. A DX chip can run scientific engineering, and math packages much faster than a SX.

Most of the time, a number followed by the letters Mhz is also included. Mhz stands for megahertz. This also known as the clock speed. One Megahertz (1 Mhz) is a signal that alternates between high and low values one million times a second. This is another way of measuring how fast the computer can process information and data. A 66Mhz chip runs twice as fast as a 33Mhz chip of the same type. For example, a 386DX 66Mhz is twice as fast as a 386DX 33Mhz.

A basic system often comes with 4 megabytes of RAM (Random Access Memory). This enough to run Microsoft Windows and DOS. It takes about 100 nanoseconds (billionths of a second) to get some data from RAM. If the data is on disk, then it takes about 10 milliseconds (thousandths of a second) to read. The disk is 100,000 times slower than memory.

Although programs will run on a 4 MEG or 8 MEG machine, programs always run better with more memory. Right now, 4 Megs of memory is the MINIMUM your system should have. Given the typical programs run by most people (ie word processors, spreadsheets), a system configured with more than the "recommended" amount of memory will normally outperform one with limited memory and a faster CPU. For example, a 486SX 33Mhz with 12 Megabytes of memory will always outperform a 486DX 66Mhz with 4 Megs of memory.

Most Display adapters are characterized by:

Resolution

Color Depth

Refresh Rate

Bus Interface

Accelerator

Resolution refers to the numbers of dots on the screen. It's expressed as a pair of numbers that give the number of dots on a line (horizontal) and the number of lines (vertical). The four most common resolutions in use today are:

640x480 (VGA)

800x600 (SVGA)

1024x768

1280x1024

A computer display is like a high resolution television. It generates colors by combining amounts of red, green, and blue. These colors are controlled by three wires in the display cable. Each has a variable amount of voltage represented by a number from 0 to 255. This produces 16 million possible colors, theoretically. Complete control of color may be needed for displaying photographs, but most ordinary applications use far fewer colors.

Color Depth (number of colors) is determined by the number of bits assigned to hold color value. The most common ones are:

4 bits-16 colors

8 bits-255 colors

16 bits-32 000 colors

24 bits-16 million colors

The display adapter stores a value (4 to 24 bits) in memory for every dot on the screen. The amount of storage needed is determined by multiplying the number of dots (resolution) by the memory required for each dot.

The Refresh Rate determines the speed that the display uses to paint the dots on the screen. The orginal VGA displays ran at 60Hz, but some people complained that this produced flickering. International standards now require a rate of 70Hz. A "multisynch" monitor can adapt to refresh rates in a range. This range is typically 60-75Hz.

The minimum you should have is a Super VGA (SVGA) adapter with 1Meg og video memory. If you buy the card separate from the system, make sure that it is designed for the type of bus you have (PCI, etc)

A personal computer may transfer data from disk to CPU, from CPU to memory, or from memory to the display adapter. A computer doesn't have separate circuits between every pair of devices. This would be too slow. The solution is a Bus. This Bus is simply a common set of wires that connect all the computer devices and chips together. Some of these wires are used to transmit data or send a number (the address) that identifies a particular device or memory location. The computer chips watch the address wires and respond when their identifying number is transmitted.

In a modern computer, there may a half dozen different Bus areas. There is a CPU area that contains the CPU, memory, and basic control logic. There is a "High Speed I/O Device" area that is either a VESA Local Bus (VLB) or a PCI Bus. In a desktop computer, only two or three cards can be plugged into the high speed sockets. The remaining I/O device slots support standard "ISA" Bus cards.

A new computer today will come with an EIDE disk controller that can handle four disks or other devices. The most common additional adapter card is a multimedia soundcard with a CD-ROM connection. The CD-ROM or the soundcard doesn't place a heavy load on even the slowest bus. Thus typical home or office users have no requirements that can strain the I/O Bus.

Sound cards are a must if you want to use multimedia technology. Sound cards allow the transfer of sounds, music, and voices to be used. A sound card consists is a card which must be installed into an empty slot inside the computer. With this card, the user can use software designed for sound cards to make their own recordings of sounds, play sounds, or just listen to the sounds and music that accompany many multimedia products. Some of the companies that make sound cards are:

A hard drive (or HDD or hard disk drive) is a permanent storage device inside the computer. The hard drive retains the computer's basic operating codes and procedures, as well as programs the user installs by themselves. Most users keep files and information that they work on or update regularly, such as financial records on the hard drive.

Printers are used to print a hardcopy of a document. A printers speed is often rated in "pages per minute" (PPM). This tells the user an estimate of how many pages they should be able to print a minute. There are many different types of printers. Some types of printers are:

Laser Printers

Laser printers use a rotating disk to reflect laser beams onto the paper. This offers almost book like print. Laser printers are fairly quiet when they print.

Inkjet Printers

An inkjet printer prints on the paper by using dropping small electrostatic ink droplets from a nozzle onto the paper. Inkjet printers are very quiet when they are running.

Dot Matrix Printers

A dot matrix printer uses closely packed needles or "pins" which can individually be forced forward to press an ink ribbon against the paper. Dot matrix printers tend to be very noisy when printing, but they are usually the cheaper printers on the market.