Caribbean Secondary Education Certificate - Information Technology/Functions of Hardware Components of a Computer System.

Introduction Computer Hardware is the physical part of a computer, as distinguished from the that executes or runs on the hardware. The hardware of a computer is infrequently changed, while software and data are modified frequently. The term soft refers to readily created, modified, or erased.

These are unlike the physical components within the computer which are hard. When you think of the term computer hardware you probably think of the guts inside your personal computer at home or the one in your classroom. However, computer hardware does not specifically refer to personal computers. Instead, it is all types of computer systems.

Computer hardware is in embedded systems in automobiles, microwave ovens, CD players, DVD players, and many more devices. In 2003, only 0.2% of all microprocessors sold were for personal computers. How many other things in your house or your classroom use computer hardware? CPU Diagram There are four steps that nearly all CPUs use in their operation: fetch, decode, execute, and writeback.

The first step, fetch, involves retrieving an instruction from program memory. In the decode step, the instruction is broken up into parts that have significance to other portions of the CPU. During the execute step various portions of the CPU, such as the (ALU) and the (FPU) are connected so they can perform the desired operation. The final step, writeback, simply writes back the results of the execute step to some form of memory. Random Access Memory Random access memory (RAM) is fast-access memory that is cleared when the computer is power-down. RAM attaches directly to the motherboard, and is used to store programs that are currently running.

RAM is a set of integrated circuits that allow the stored data to be accessed in any order (why it is called random). There are many different types of RAM. Distinctions between these different types include: writable vs. Read-only, static vs. Dynamic, volatile vs. Non-volatile, etc.

Firmware Firmware is loaded from the Read only memory (ROM) run from the Basic Input-Output System (BIOS). It is a computer program that is embedded in a hardware device, for example a microcontroller. As it name suggests, firmware is somewhere between hardware and software. Like software, it is a computer program which is executed by a microprocessor or a microcontroller. But it is also tightly linked to a piece of hardware, and has little meaning outside of it. Most devices attached to modern systems are special-purpose computers in their own right, running their own software.

Some of these devices store that software (“firmware”) in a ROM within the device itself. Power Supply The power supply as its name might suggest is the device that supplies power to all the components in the computer. Its case holds a transformer, voltage control, and (usually) a cooling fan.

The power supply converts about 100-120 volts of AC power to low-voltage DC power for the internal components to use. The most common computer power supplies are built to conform with the ATX form factor. This enables different power supplies to be interchangable with different components inside the computer. ATX power supplies also are designed to turn on and off using a signal from the motherboard, and provide support for modern functions such as standby mode. CD CDs are the most common type of removable media. They are inexpensive but also have short life-span. There are a few different kinds of CDs.

CD-ROM which stands for Compact Disc read-only memory are popularly used to distribute computer software although any type of data can be stored on them. CD-R is another variation which can only be written to once but can be read many times. CD-RW (rewritable) can be written to more than once as well as read more than once. Some other types of CDs which are not as popular include Super Audio CD (SACD), Video Compact Discs (VCD), Super Video Compact Discs (SVCD), PhotoCD, PictureCD, CD-i, and Enhanced CD. DVD DVDs (digital versatile discs) are another popular optical disc storage media format. The main uses for DVDs are video and data storage.

Most DVDs are of the same dimensions as compact discs. Just like CDs there are many different variations. DVD-ROM has data which can only be read and not written.

DVD-R and DVD+R can be written once and then function as a DVD-ROM. DVD-RAM, DVD-RW, or DVD+RW hold data that can be erased and re-written multiple times. DVD-Video and DVD-Audio discs respectively refer to properly formatted and structured video and audio content. The devices that use DVDs are very similar to the devices that use CDs. There is a DVD-ROM drive as well as a DVD writer that work the same way as a CD-ROM drive and CD writer. There is also a DVD-RAM drive that reads and writes to the DVD-RAM variation of DVD.

Blu-ray Blu-ray is a newer optical disc storage media format. Its main uses are high-definition video and data storage. The disc has the same dimensions as a CD or DVD. The term “Blu-ray” comes from the blue laser used to read and write to the disc. The Blu-ray discs can store much more data then CDs or DVDs.

A dual layer Blu-ray disc can store up to 50GB, almost six times thecapacity of a dual layer DVD (WOW!). Blu-ray discs have similar devices used to read them and write to them as CDs have. A BD-ROM drive can only read a Blu-ray disc and a BD writer can read and write a Blu-ray disc.

Floppy Disk A floppy disk is a type of data storage that is composed of a disk of thin, flexible(“floppy”) magnetic storage medium encased in a square or rectangular plastic shell. Floppy disks are read and written by a floppy disk drive. Floppy disks are a dying and being replaced by the optical and flash drives. Many new computers do not come with floppy drives anymore but there are a lot of older ones with floppy drives lying around. While floppy disks are very cheap the amount of storage on them compared to the amount of storage for the price of flash drives makes floppy disks unreasonable to use.

Hard Disk Drive A hard disk drive (HDD) is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Just about every new computer comes with a hard disk these days unless it comes with a new solid-state drive. Typical desktop hard disk drives store between 120 and 400GB, rotate at 7,200 rpm, and have a madia transfer rate of 1 Gbit/s or higher. Hard disk drives are accessed over one of a number of bus types, including parallel ATA(also called IDE), Serial ATA (SATA), SCSI, Serial Attached SCSI, and Fibre Channel.

Computer Awareness is tested in almost every exam. Some exams like SBI PO, SBI Clerk, IBPS PO, IBPS Clerk, SSC CGL, Railways RRB etc. Require you to have Basic Computer Knowledge. One of the oft seen topics in Computers is Hardware. Basic Computer Hardware questions are easy to remember and can count for easy marks. Use these Computer Notes to familiarize yourself with Basic Computer Hardware. Download as PDF for revision later.

About Basic Computer Hardware Every part of your computer is the result of years of research and development. Parts that were once hand made at a cost of thousands of man-hours are now mass produced for a fraction of a rupee. Computer parts can be divided into two groups, hardware and software. Hardware is any part of the computer that you can touch. The seeming miles of wires that get tangled on your desk, the CD drive, the monitor are all hardware. Software is a set of electronic instructions consisting of complex codes (Programs) that make the computer perform tasks.

Windows is a software, so is any other program that runs on your computer. While there are thousands of parts even in the smallest computers that make up its hardware, you are not required to know them all. You only need to know about basic computer hardware. Basic computer hardware consists of the following parts: 1.

CPU (Central Processing Unit) The CPU is considered the brain of the computer. It performs all types of data processing operations, stores data, intermediate results and instructions (program). It controls the operation of all parts of computer. A CPU has 3 components as listed below.

(A) CU (Control Unit) The control unit (CU) is a component of a computer’s central processing unit (CPU) that directs operations of the processor. It tells the computer’s memory, arithmetic logic unit and input and output devices how to respond to a program’s instructions. However, the Control Unit doesn’t process any data. (B) ALU (Arithmetic Logic Unit) Think of the ALU as the logical part of the brain. When any mathematical calculation or decision/logic needs to be carried out, the instruction is passed on to the ALU.

The ALU thinks in bits (i.e. Binary digits – ‘0’s and ‘1’s.) It is made up of a group of memory locations built directly into the CPU called registers.

These are used to hold the data (binary information) that are being processed by the current instruction. (C) Memory Primary memory is memory that is part of the computer itself and necessary for its functioning. It consists of mainly two types of memories: (i) Random Access Memory (RAM) RAM is the internal memory of the CPU for storing data, program and program result. It is read/write memory which stores data until the machine is working. As soon as the machine is switched off, data is erased.

RAM is volatile. Burns Leadership 1978 Pdf Viewer on this page. Volatile means that the data stored in memory is lost when we switch off the computer or if there is a power failure. Hence a backup Uninterruptible Power System (UPS) is often used with computers.

There are different types of RAM available. Some of them are described below. • Dynamic Random Access Memory (DRAM): A type of physical memory used in most personal computers. The term dynamic indicates that the memory must be constantly refreshed or it loses its contents.

This type of memory is more economical. • Static Random Access Memory (SRAM): A type of memory that is faster and less volatile than DRAM, but requires more power and is more expensive. The term static is derived from the fact that it does not need to be refreshed like DRAM. • Synchronous Dynamic Random Access Memory (SDRAM): A type of DRAM that has a much higher processing speed. (ii) Read Only Memory (ROM) The memory from which we can only read but cannot write on it. This type of memory is non-volatile.

The information is stored permanently in such memories during manufacture. A ROM, stores such instructions that are required to start a computer. This operation is referred to as bootstrap. The different types of ROM are given below. • MROM (Masked ROM): The very first ROMs were hard-wired devices that contained a pre-programmed set of data or instructions. These kinds of ROMs are known as masked ROMs which are inexpensive.

The MROM cannot be programmed by the user. • PROM (Programmable Read only Memory): PROM is read-only memory that can be modified only once by a user. The user buys a blank PROM and enters the desired contents using a PROM program. • EPROM (Erasable and Programmable Read Only Memory): The EPROM is a type of a PROM which can be programmed by the user multiple times. EPROM is erased by exposing it to ultra-violet light for a duration of up to 40 minutes. Usually, an EPROM eraser achieves this function.

• EEPROM (Electrically Erasable and Programmable Read Only Memory): The EEPROM is programmed and erased electrically. It can be erased and reprogrammed about ten thousand times. Both erasing and programming take about 4 to 10 milliseconds. Secondary Storage (External Storage Devices) Floppy diskettes, hard disk, tapes and optical disks come under the category of external storage devices or ancillary storage devices.

These devices are very sensitive to environmental conditions (humidity and temperature) as well as to external magnetic fields and need to be stored carefully. They are not compulsory for the functioning of the computer but are useful for expanding the computer’s memory. (A) Floppy Disk Floppy disks are primarily used on PCs.

Information on a floppy disk is recorded in the magnetized states of particles of iron oxides evenly placed upon concentric circles known as tracks. (B) Hard Disk It is a non-removable enclosed magnetic disk included in most PCs. It contains a stack of metal platters, each coated with iron oxide, that spin on a spindle and the entire unit is encased in a sealed chamber. (C) Magnetic Tape This is plastic tape, usually made of Mylar that is coated with iron oxide, thereby enabling the introduction (writing); retention (memory) and reading of magnetically recorded information. The best use of tape storage is for data that you do not use very often. (D) Optical Disc Drive An optical disc drive (ODD) is a disk drive that uses laser light or electromagnetic waves for reading or writing data to or from optical discs (normally CD-ROM).

A CD-ROM is a pre-pressed optical compact disc which contains data. The name is an acronym which stands for “Compact Disc Read-Only Memory”.

Computers can read CD-ROMs, but cannot write to CD-ROMs which are not writable or erasable. (E) USB A USB flash drive, also commonly known as a USB drive, USB stick and a variety of other names. It is a data storage device that includes flash memory with an integrated USB interface. USB flash drives are typically removable and rewritable, and physically much smaller than an optical disc. (3) Peripherals Peripheral devices are devices connected to the computer externally.

If a peripheral device is disconnected, the computer will still be able to work; only functions performed by this peripheral device will not be available. Here are the most used types of peripheral devices: (A) Keyboard The most common and very popular input device which helps in inputting data to the computer. It consists of keys that are capable of inputting alphabets, numbers and special characters. You can also navigate using the keyboard and perform shortcut functions. (B) Mouse Mouse is the most popular pointing device and cursor-control device having a small palm size box with a round ball at its base which senses the movement of mouse and sends corresponding signals to CPU when the mouse buttons are pressed. (C) Monitors Monitors, commonly called as Visual Display Unit (VDU), are the main output device of a computer. It forms images from tiny dots, called pixels that are arranged in a rectangular form.

The sharpness of the image depends upon the number of pixels. (D) Printer Printer is an output device, which is used to print information on paper.

• Impact Printers: The impact printers print the characters by striking them on the ribbon which is then pressed on the paper. • Non-Impact Printers: Non-impact printers print the characters without using ribbon. These printers print a complete page at a time so they are also called as Page Printers. Laser Printers, Inkjet Printers. (E) Joy Stick It is a device used to move cursor position on a monitor screen. It is mainly used in Computer Aided Designing (CAD) and playing computer games.

(F) Scanner A scanner allows you to scan printed material and convert it into a file format that may be used within the PC. (G) Plotter A plotter is used to create high-quality visuals on paper. Plotters were used in applications such as computer-aided design, though they have generally been replaced with wide-format conventional printers. A plotter gives a hard copy of the output. It draws pictures on a paper using a pen. It can be used to create presentation-charts, graphics, tables and high quality technical drawings.

There are two types of plotter. • Drum Plotter: The paper is placed over the drum that rotates back and forth. A carriage holding one or more pens is mounted horizontally across the drum. The carriage with the pens moves horizontally over the paper.

Each pen could be filled with different colours. This plotter has the ability to produce colour pictures. • Flat Bed Plotter: In flat bed plotter, the paper does not move. The carriage holding the pens should provide all motions. Inkjet plotters can also produce large drawings with different colours. Liked these Basic Computer Hardware Notes? Read more Computer notes!