Hardware - What Makes Computers Go?

by Andy Rush

There are two basic categories of computer components: What goes inside the computer Case , and what is outside the case; the Peripherals . In the picture to the left, you see a computer case (back left) with all of it's peripherals: monitor (with the blue screen); speakers on each side; a mouse (that's a computer mouse in front of the left speaker); and a keyboard (in front of the monitor).

What's Inside

Let's start with what's in the case first. The computer needs power to work so you need a Power Supply . The Power Supply takes the electricity from the wall and distributes it throughout the computer. It basically is a metal rectangular box with multiple wires coming from it. Power is provided, first and foremost, to the Motherboard (left) and the CPU. The motherboard is the framework of circuits and connections to the components of the computer. The CPU, or central processing unit sits in a socket on the motherboard. Currently Pentium IV chips of up to 2800MHz or 2.8GHz (!) are being used. The CPU does most of the "thinking" for the computer and the information travels over the circuits of the motherboard. Data is moved back and forth from the CPU to the other internal and external components of the computer.

There is lots of data moving within the computer, and in order to handle it all the computer needs some microchips with some data storage capabilities. These chips will only contain data while the computer is powered on. They are known as RAM chips. RAM stands for random access memory and any software programs that you are using for a particular computing session are maintained in these chips. While you use the software, data will be updated on the Display (more about displays later). When you stop using the software, the memory that the program was using gets flushed out.

Obviously if this RAM is only good while the computer is on, we need to have some other storage areas that will keep the information even when the computer is off.  Enter the Disks! As in Hard Disks and Floppy Disks. These disks have data placed on them and removed from them while the computer is on, and they keep it safe (or reasonably safe) when the computer is off. The disks work very much like an audio tape. You record some music to the tape and you can play it back over and over. Well the same goes for the data on your disks. You record (or "write") data to the disk, and you can retrieve it ("read" it) as many times as you want. Hard disks have a much greater capacity than floppy disks. The high capacity consumer hard disks hold 160 Gigabytes, or more, of data. That's well over 100,000 times the data that a single floppy disk can contain. However, hard disks have one drawback that floppy disks don't have. They aren't removable (though you can purchase external hard disks). Hard disks are what is known as fixed media. Floppy disks are known as removable media. Floppy disks can hold roughly 1,000 pages of text on a disk. Also, since they are portable they can transport several documents from one computer to the next.

In between floppy disks and hard disks are CD-ROMs, CD-Rs, CD-RWs, and Zip disks. CD-ROM stands for compact disc - read only memory. What that means is that they are very much like the CDs that play music, but they have computer data on them. In addition you can only retrieve data from them. They are "read only", no writing (recording) data to them. CD-ROMs hold about 600,000 pages of text. CD-Rs are writeable, and CD-RWs are rewriteable, meaning you can record data on these special CDs over and over again. Zip disks are much like floppy disks, but have a capacity of either 100, 250 or 750 megabytes. That means they can hold a minimum of 100,000 pages of text and can be read from and written to. You need a special Zip drive installed in your machine to read these disks. Just like you need a CD-ROM drive to read CD-ROMs, and a floppy disk drive to read floppy disks, you need a Zip drive to read Zip disks. A hard disk drive is a self-contained unit that houses the media. Hard disk drives, as well as floppy disk and CD-ROM drives have been standard on most machines for a while, and now CD or even DVD writers are coming standard. Zip disks drives are falling out of favor as an option.

Remember, all that memory and media holds data and software that make your computer a usable device. However, all that media and memory don't mean anything if you don't have some device to allow you to interact with the computer. In order to use the software on a computer, you need things like a Keyboard to type words and commands, and you need a Mouse to move the arrow that points to the icons that represent the computer components and software applications. We'll talk about the mouse and keyboard in a future section on peripherals.

The last couple of items we should mention that are found inside the case of the computer are several different types of ports , and the expansion slots . The Serial Port and the Parallel Port are found on the back of the computer. The serial port is also known as a communication port. It allows devices such as modems to be connected externally to the computer. The parallel port is also known as the printer port. Printers get connected here. However, those ports are falling out of favor, and new types of ports, called USB, are now a standard on new computers. USB ports are high speed serial ports that newer modems, printers, scanners, speakers, monitors, and other devices can connect to.

Expansion slots allow other devices not on the motherboard to be connected. For example, a video display card, sound card, or a network interface card would be inserted into the expansion slots to, connect to a display monitor, give you sound for your computer, or connect to a high speed network, respectively. Some computers, however, have these devices built into the motherboard, which in turn can make the computer smaller.