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NAME: OLUWATAYO OLUWASEYI TOLUWALASE DEPARTMENT: MEDICINE AND SURGERY COURSE: GST 115 ASSIGNMENT: LIST AND DISCUSS THE SIX CATEGORIES OF COMPUTER HARDWARE 1. Central Processing Unit (CPU) 2. Main Memory. 3. Secondary Storage 4. Input Devices 5. Output Devices 6. Connectivity Hardware 1. The Central Processing Unit (CPU): The CPU is the most important component of a computer system. It is the brain of the computer system and it determines the capacity of the compute system. It connects other components and directs them according to the available program. All other hardware components of computer system connect to CPU in order to carry out instructions. These other components cannot work on their own without the CPU. The CPU has two major parts, the Arithmetic and Logic Unit (ALU) and the control unit (CU).These two parts of CPU contain registers. Registers are high speed storage location that temporarily holds data and instructions during processing. The ALU and CU have different registers with different functions. The arithmetic and logic unit: this is the part of CPU which handles arithmetic operation such as addition, subtraction, multiplication and division. It has the ability to carry out reasoning and decision making, thus performs logical operations such as greater than (>), less than (<), equal to (=) and not equal to signs. The registers available in ALU are Adder and Accumulator. The control unit: the control unit interprets the instructions from the main memory. It gives instructions to ALU on what operation and how to carry it out. It gives directives to the peripheral devices of the computer system and it controls all the activities of the computer. It has three registers which include the following; instruction register, instruction decoder, program counter. 2. The Main Memory: The main memory is a storage media on the motherboard. It is used to store data and instructions to be executed by the CPU. Main memory is closer to the CPU than any secondary storage device, it is the memory that CPU used to access often and often. The main memory of a computer system can be classified into three distinct categories which are Random Access Memory, Read only Memory (ROM) and Complementary Metal oxide semi-conductor memory (CMOS). Random Access Memory (RAM): it is a volatile type of memory. In case of power failure, information on RAM is lost. It is a temporary storage medium used to hold the data and instructions currently working on by the computer system. Read Only Memory (ROM): it is a non-volatile type of memory. Power failure does not affect the content or ROM. It allows to read its contents but do not allow the users to change it or write it. It is used to store permanent instructions and data. ROM is used to store instructions that control the activities of the computer system. Complementary metal oxide semi-conductor memory (CMOS): it is a hybrid derived from the combination of some properties of RAM and ROM. CMOS is non-volatile and the content can be changed easily. It is often used to store configuration information of computer system like size of hard disk, current time and date. It doesn’t store any program. 3. Secondary Storage: the central processing unit can only process data instruction on RAM. As RAM is volatile what happens to the data processed? The processed data must be stored in another storage device. Do not think of ROM as the solution as ROM does not allow users to interact freely, then the need for secondary storage device that user can easily interact with. Types of secondary storage 1. Magnetic media: this is a type of secondary storage. It includes the floppy disk, hard disk, and magnetic tape. 2. Optical media: these are storage media that hold content in digital form and that are written and read by a laser. These storage media group include all the various CD and DVD variations. 3. Semi-conducting media: These are often called flash memories. They use semiconductor clips to store data. They are very reliable and durable. They are silent in operation and they are used in some portable devices such as digital cameras, PDA and MP3. Examples include: Microdrive (MD), Secure Digital Card(SD card), compact flash card (Cfcard) and Smart Media Card(SM card). 4. Input devices: input devices are the devices that allow users to enter data and command into the computer system. Some of these devices are described below. TYPES OF INPUT DEVICES 1 .Keyboard 2. Moue 3. Joystick 4. Scanner 5. Bar Code Reader 1. Keyboard: A keyboard is a well-known input device which contains alphabets, numeric/digits, special keys, function keys etc. keyboard can be of serial or parallel. Alphabets: - A to Z, a to z. Numeric keys: - 0-9 Special keys: - shift, spacebar, ctr, alt etc. Functions key: - F1, F2…….F12. Keyboard is used to convert these above mentioned keys into digital form of computer. 2. Mouse: A mouse is an input device which is also called a pointing device. It is used to move the cursor on the screen. Mouse works in GUI (Graphical User Interface) mode. Mouse is of different types in which some are physical mouse, optical mouse, and cordless mouse. 3. Joystick: It is also called as game controller device. Joystick is a remote control device which is used in gaming purpose. We will also play with keyboard but joystick gives more simplicity and more speed than keyboard. 4. Scanner: Scanner is an example of input device which are mainly used to check OMR sheets. It is also used to copy text, images in the form of soft copy. 5. Bar Code Reader (BCR): Bar Code Reader is generally used in shopping malls; BCR read the bar code and display the rate of item on the computer screen. It is also used to recognize courier products. BCR takes input in the form of code and convert this bar code into computer language (0 or 1). 5. Output devices: An output is a hardware that presents digital information in form that human being can understand. Types of output devices 1. Visual Display Unit (VDU): It is commonly referred to as monitor. There are two technologies for VDU; (i) cathode ray tubes (CRT). (ii) Liquid crystal display (LCD). 2. Data projector: it use strong light rays to project the computer display onto a large screen for a group of people to see. The projectors used in this school are LCD projector. 3. Printer: it is an output device that output texts and graphics on a physical medium such as paper or transparency film. The printed information is called the hardcopy. Printers can be divided into two categories; (i)impact printers which produces printed images by physically striking pins against an ink ribbon to leave dots on the paper. Examples include dot-matrix printer. (ii)non-impact printers which output information on paper without physically striking the paper. There are 3 types which include; ink-jet printer, laser printer, thermal printer. 4. Speakers 5. Headsets. 6. Computer output or microfilm (COM). 6. CONNECTIVITY HARDWARE: Connectivity hardware is the hardware that allows computer to be physically connected to different type of networks. EXAMPLES OF CONNECTIVITY HARDWARE 1. Modem 2. Router 3. Network interface controller 4. Ethernet hub 5. Brouter 1. Modem: A modem (modulator-demodulator) is a device that modulates one or more carrier wave signals to encode digital information for transmission and demodulates signals to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used with any means of transmitting analog signals, from light emitting diodes to radio. A common type of modem is one that turns the digital data of a computer into modulated electrical signal for transmission over telephone lines and demodulated by another modem at the receiver side to recover the digital data. 2. Router: A router is a networking device that forwards data packets between computer networks. Routers perform the “traffic directing” functions on the internet. A data packet is typically forwarded from one router to another through the networks that constitute the internetwork until it reaches its destination node. A router is connected to two or more data lines from different networks (as opposed to a network switch, which connects data lines from one single network). When a data packet comes in on one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. This creates an overlay internetwork. The most familiar types of routers are home and small office routers that simply pass data, such as web pages, email. 3. Network interface controller: A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter or physical network interface and by similar terms) is a computer hardware component that connects a computer to a computer network. Early network interface controllers were commonly implemented on expansion cards that plugged into a computer bus. The low cost and ubiquity of the Ethernet standard means that most newer computers have a network interface built into the motherboard. Modern network interface controllers offer advanced features such as interrupt and DMA interfaces to the host processors, support for multiple receive and transmit queues, partitioning into multiple logical interfaces, and on-controller network traffic processing such as the TCP offload engine. 4. Ethernet hub: An Ethernet hub, active hub, network hub, repeater hub, multiport repeater, or simply hub is a device for connecting multiple Ethernet devices together and making them act as a single network segment. It has multiple input/output (I/O) ports, in which a signal introduced at the input of any port appears at the output of every port except the original incoming. A hub works at the physical layer (layer 1) of the OSI model. Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if it detects a collision. In addition to standard 8P8C (‘’RJ45’’) ports, some hubs may also come with a BNC or Attachment unit interface (AUI) connector to allow connection to legacy 10BASE2 or 10BASE5 network segments. 5. Brouter: A brouter (pronounced BRAU-tuhr or sometimes BEE-rau-tuhr) is a network bridge and a router combined in a single product. A bridge is a device that connects on local area network (LAN) to another local area network that uses the same protocol (for example, Ethernet or token ring). If a data unit on one LAN is intended for a destination on an interconnected LAN, the bridge forwards the data unit to that LAN; otherwise, it passes it along the same LAN. A bridge usually offers only one path to a given interconnected LAN. A router connects a network to one or more other networks that are usually part of a wide area network (WAN) and may offer a number of paths out to destinations on those networks.