Sometimes, like in a school computer lab or in an office, you need to hook up several computers to one printer, or several computers need to connect to one file server, or maybe you have several devices (such as a scanner and a CD-ROM player) that you need to hook into one computer. Well, the only way to connect all these devices together, since there is only one port, or connecting place, on the back of the computer, is to connect each object (each device) to the next one in line, making a daisy chain. [Read more…] about What is Daisy chain?

Cylinder The set of all the TRACKS on a HARD DISK drive with multiple PLATTERS that may be read at the same time. All the tracks are the same distance from the central spindle, so they can be imagined as tracing a cylinder in space. The HEADS on all the platters move together in a parallel motion – a sequence of data stored within the same cylinder can be read at optimum speed without requiring any movement.

CMOS (Complementary Metal-Oxide Semiconductor) The most popular fabrication process for modern INTEGRATED CIRCUITS, which employs LOGIC GATES made out of complementary pairs of FIELD-EFFECT TRANSISTORS called the P-CHANNEL and N-CHANNEL respectively. The p-channel transistor is made within a well of n-type silicon, while the n-channel is made directly in the doped silicon SUBSTRATE. These two transistors are arranged so that a current flows only momentarily while the gate is switching, and none flows in its on or off states, which enormously reduces power consumption as compared with older BIPOLAR processes. It is this benign property that permits the phenomenal improvement in chip performance over recent decades that is referred to as MOORE’S LAW.

clock cycle The basic unit of timing within a computer system, consisting of one of the stream of regular pulses generated by the SYSTEM CLOCK. Most of a computer’s components, in particular its processor, bus and memory systems, operate in strict step with the clock, so the number of clock cycles their various actions occupy is of crucial importance to a computer designer. [Read more…] about What is clock cycle and clock signal?

CD-R (Compact Disc Record-able) A WRITE-ONCE version of the CD-ROM disc, which can be used to distribute and back up computer data or to copy music CDS. Though it follows the same data format and can be read in standard CD-ROM drives, CD-R employs quite a different physical storage process, based on an organic dye film that is selectively bleached by a laser beam, which explains the blue or green colour of the recording surface. [Read more…] about What is CD-R (Compact Disc Recordable)?

A microprocessor is a single chip that is the central processing unit, or the brains of a computer. To function as a complete computer, it also needs memory, a clock) and a power supply. Well, a computer on a chip has its own built-in clock and its own memory, so all it needs is a power supply to function. These tiny things are used in all kinds of things, from car parts to children’s toys.

COMMAND.COM is the program that serves as the DOS command processor, or the DOS shell if you prefer. Like any operating system, DOS itself is simply software, albeit software that has a very special role in running your computer. Dos consists of a conglomeration of programs, utilities, and device drivers, but at its core are three key pieces of software. They must be present on the disk you use to start your computer, or the computer won’t work. Of these three pieces of software, the only one you’re likely to run across is Command.com you’ll see it in the list of files on your screen when you display the directory of that start-up disk, by typing DIR and pressing Enter. (The other two essential DOS files are hidden files, so you won’t see them in the directory list.) [Read more…] about What is COMMAND.COM?

A cluster is the smallest single unit of the space on a disk (a hard disk or a floppy or even an optical disc) that your computer’s operating system keeps track of separately. The operating system keeps systematic records of which clusters are occupied by each file stored on the disk (in DOS, this is called the file allocation table, or FAT). Clusters usually consist of more than one sector, a sector being the smallest unit of disk space that the computer can read data from or write data on. There are too many sectors on a hard disk to keep track of them all individually, so the operating system deals with them in groups called clusters instead. [Read more…] about What is cluster?

Clock speed refers to how fast the system clock drives the computer’s CPU (central processing unit, the chip that runs the computer) which determines how fast the system as a whole can process information internally. Clock speed is measured in megahertz; a speed of one megahertz (l MHZ) means the system clock is sending out its electric current one million times per second. The higher the clock speed of a computer, the faster the computer can operate, assuming all other factors are equal. However, clock speed isn’t the only factor that determines your computer’s overall performance, or even how fast the microprocessor (another term for the cpu) gets things done. Two different microprocessors may run at the same clock speed, and still take different amounts of time to finish a given job. [Read more…] about What is Clock Speed or Clock Rate?

CD-ROM (pronounced “see-dee rom”) stands for compact disk, read only memory. A NON-VOLATILE OPTICAL DISK STORAGE medium based on the same physical disk format as the audio Compact Disc (CD), developed by Philips and Sony. A CD-ROM actually looks just like the CDs we play music with. To use one with your computer, you need a CD-ROM player, also called a CD-ROM reader. A CD-ROM can hold up to about 600 megabytes of information, which is the equivalent of about 700 regular floppy disks. There are CD-ROMs that hold the entire works of Shakespeare, complete dictionaries, histories, images of the works in the Louvre, etc. You can search the CD for the particular information you want to work with, copy it, then paste it into your own documents on your hard disk to do with what you will. You can only read from a CD-ROM, though-you can’t store information onto it. The biggest complaint about CD-ROMs is that they are relatively slow. [Read more…] about What is CD-ROM?

A card, or printed circuit board, also known as a board, is a piece of plastic with chips attached to it. Chips are the tiny little circuits that run the computer. You buy a card and stick it inside the computer box. You can get accelerator cards (boards) that make your computer run faster, video cards that give your computer more graphic capability, and clock cards and printer cards or whole computers on a card. They range in price depending on what they do, who makes them, and so on. For instance, an accelerator card can cost $300-$1500. [Read more…] about What is Card?

Bootstrap: To start a computer by loading its OPERATING SYSTEM from disk storage into memory. The name alludes to the seeming absurdity of trying to lift oneself off the floor by pulling on one’s own bootstraps – since it is the operating system that enables a computer to read disks, then loading itself from disk would seem to be a similar impossibility. This paradox is resolved by the presence of a small program called the BOOTSTRAP LOADER, which resides permanently in the computer (stored in a ROM chip) and contains just sufficient code to read the rest of the operating system from disk. This process is informally called ‘booting’ or ‘booting up’ the computer. [Read more…] about What is Bootstrap and Bootstrap Loader?

Boot Sector Virus: A computer VIRUS program that hides its code within the BOOT SECTOR of a FLOPPY DISK, so that the virus code is executed before the operating system itself has loaded, making countermeasures difficult to apply. Once loaded into memory, such a virus infects the boot sectors of any other floppy disk that is placed in the drive, hence ensuring its spread. [Read more…] about What is Boot Sector Virus?