Preliminary Exam (Reviewer) 09_25_24.pdf

Preliminary Exam (Reviewer): September 25 PCAS111 - PC Assembly, Troubleshooting and Maintenance Lesson 1: Components Of Computer System Computer System - A computer system consists of hardware and software components. Hardware - is the physical equipment....

Preliminary Exam (Reviewer): September 25 PCAS111 - PC Assembly, Troubleshooting and Maintenance Lesson 1: Components Of Computer System Computer System - A computer system consists of hardware and software components. Hardware - is the physical equipment. Operating System (OS) - instructs the computer how to operate. Application Software - performs different functions or program with specific task. COMPUTER HARDWARE: A. Motherboard - The motherboard is the main printed circuit board and contains the buses, or electrical pathways, found in a computer. These buses allow data to travel between the various components the comprise a computer. A motherboard is also known as the system, the backplane, or the main board. B. Central Processing Unit (CPU) - The CPU executes a program, which is a sequence of stored instructions. Each model of processor has an instruction set, which it executes. The CPU executes the program by processing each piece of data as directed by the program and the instruction set. Reduced Instruction Set Computer (RISC) - Architectures use a relatively small set of instructions, and RISC chips are designed to execute these instructions very rapidly. Complex Instruction Set Computer (CISC) - Architectures use a broad set of instructions, resulting in fewer steps per operation. Overclocking - is a technique used to make a processor work at a faster speed than its original specification. Overclocking is not a reliable way to improve computer performance and can result in damaging the CPU. MMX - Is a set of multimedia instructions built into intel processors MMX enabled microprocessors can handle many common multimedia operations that are normally handled by a separate sound or video card. However, only software especially written to call MMX instructions can take advantage of the MMX instructions set. Single Core CPU - One core inside a single CPU chip that handles all of the processing capability. A motherboard manufacturer may provide to build a powerful, multi-processor computer. Dual Core CPU – Two cores inside a single CPU chip in which both cores can process information at the same time.  C. Random-Access Memory (RAM) – It is the temporary storage for data and programs that are being accessed by the CPU. Different Types of RAM: Dynamic Random Access Memory (DRAM) – Is a memory chip that is used as main memory. DRAM must be constantly refreshed with pulses of electricity in order to maintain the data stored within a chip. Static Random Access Memory (SRAM) – Is a memory chip that is used as cache memory. SRAM is much faster than DRAM and does not have to be refreshed as often. Fast Page Mode DRAM (FPM Memory) – Is memory that supports paging. Paging enables faster access to the data than regular DRAM. Most 486 and Pentium systems from 1995 and earlier use FPM memory. Extended Data Output RAM (EDO Memory) – Is memory that overlaps consecutive data accesses. This speed up the access time to retrieve data from memory, because the CPU does not have to wait from one data access cycle to end before another data access cycle begins. Synchronous DRAM (SDRAM) – Is DRAM that operates in synchronization with the memory bus. The memory bus is the data path between the CPU and the main memory. Double Data Rate 2 SDRAM (DDR2 SDRAM) – Is faster than DDR SDRAM memory. DDR2 SDRAM improves performance over DDR SDRAM by decreasing noise and crosstalk between the signal wires. Rambus DRAM (RDRAM) – Is a memory chip that was developed to communicate at very high rates of speed. RDRAM chips are not commonly used. D. Power Supply – The power supply unit is the piece of hardware that’s used to convert the power provided from the outlet into usable power for the many parts inside the computer case. E. Video Card – A video card is a piece of computer hardware that’s numerous contacts on the bottom of the card and one or more ports on the side for connection to video displays and other devices. F. Hard Drives and Floppy Drives – A storage drive reads or writes information to magnetic or optical storage media. The drive can be used to store data permanently or to retrieve information from a media disk. Here are Some Common Types of Storage Drives: A floppy drive, or floppy disk drive, is a storage device that uses removable 3.5-inch floppy disk. A hard drive, or hard disk drive, is a magnetic storage device that is installed inside the computer.  An optical drive is a storage device that uses lasers to read data on the optical media. There are two types of optical drives CD and DVD media which can be pre-recorded (read-only), recordable (write once), or re-recordable (read and write multiple times).These are several types of optical media: CD-ROM – CD read only memory media that is pre-recorded. CD-R – CD-recordable media that can be recorded once. CD-RW – CD-rewritable media that can be recorded, erased, and recorded DVD-ROM – DVD read-only memory media that is pre-recorded DVD-RAM – DVD-random access memory media that can be recorded, erased, and re-recorded. DVD+/-R – DVD-recordable media that can be recorded once. DVD+/-RW – DVD-rewritable media that can be recorded, erased, and re-recorded. Flash drive, also known as a thumb drive, is a removable storage device that connects to a USB port. A flash drive uses a special type of memory that requires no power to maintain the data. Hard drives and optical drives are manufactured with different interfaces that are used to connect the drive to the computer. To install a storage drive in a computer, the connection interface on the drive must be the same as the controller on the motherboard. Here are some common drive interfaces: Integrated Drive Electronics (IDE) – also called Advanced Technology Attachment (ATA) is an early drive controller interface that connects computers and hard disk drives. An IDE interface uses a 40_pin connector. Enhanced Integrated Drive Electronics (EIDE) – also called ATA-2, is an updated version of the IDE drive controller interface. EIDE supports hard drive larger than 512MB, enables Direct Memory Access (DMA) for speed, and uses the AT Attachment Packet interface (ATAPI) to accommodate optical drives and tape drives on the EIDE bus. An EIDE interface uses a 40-pin connector. Parallel ATA (PATA) – refers to the parallel version of the ATA drive controller interface. Serial ATA (SATA) – refers to the serial version of the ATA drive controller interface. A SATA interface uses a 7-pin connector. Small Computer System Interface (SCSI) – is a drive controller interface that can connect up to 15 drives. SCSI connect both internal and external drives. An SCSI interface uses a 50-pin, 68-pin, or 80-pin connector. PORTS AND CABLES a. Serial Ports and Cables – A serial port can be either a DB-9 or a DB-25 male connector. Serial ports transmit one bit of data at a time. b. USB Ports and Cables – The Universal Serial Bus (USB) is a standard interface that connects peripheral devices to a computer c. FireWire Ports and Cables – FireWire is a high-speed, hot-swappable interface that connects peripheral devices to a computer. d. Parallel Ports and Cables – A parallel port on a computer is a standard Type A DB-25 female connector, The parallel connector on a printers may use a Type C high-density 36-pin connector. e. SCSI Ports and Cables – a SCSI port can transmit data at rates in excess of 320Mbps and can support up to 15 devices. If a single SCSI device is connected to an SCSI port, the cable can be up to 80 feet (24.4m) in length. DB-25-female connector,High-density-50-pin female connector High-density 68-pin female connector f. Network Ports and Cables – A network port, also known as an RJ-45 port, connects a computer to a network. The connection speed depends on the type of network port. g. PS/2 Ports – a PS/2 port connects a keyboard or a mouse to a computer. The PS/2 port is a 6-pin mini-DIN female connector. h. Audio Ports – An audio port connects audio devices to the computer. Line In – Connects to an external source, such as a stereo system. Microphone – Connects to a microphone Line Out – Connects to speakers or headphones Game port/MIDI – Connects to a joystick or MIDI-interfaced device l. Video Ports and Connectors – A video port connects a monitor cable to a computer. There are several video port and connector types: Video Graphics Array (VGA) – VGA has a 3-row 15-pin female connector and provides analog output to a monitor. High Definition Multimedia Interface (HDMI) – HDMI has a 19-pin connector and provides digital video and digital audio signals. Component/RGB – RGB has three shielded cables (red, green, blue) with RCA jacks and provides analog video signals. Lesson 2: Operating System and Application Software Operating System - The operating system is the most important program that runs on a computer. Computer operating system perform basic tasks, such as recognizing input from the keyboard, sending output to the display, keeping files and directories on the storage drives, and controlling peripheral devices, such as printers. Four Main Roles of operating system: Manage hardware Run applications Provide a user interface Manage files Purpose of an Operating System The operating system boots the computer and sets up the file system. 2 types of operating system interfaces: Command Line Interface (CLI): The user types commands at a prompt. Graphical User Interface (GUI): The user interacts with menus and icons. Operating System Functions: File and folder management - The operating system creates a file structure on the hard disk to drive to allow data to be stored. Application management - The operating system manage all programs to ensure that the correct resources are allocated to the applications. Control hardware access - The operating system handles the interaction between the applications and hardware. User interface - The operating system enable the user to interact with software and hardware. Plug and Play Technology: The operating system is designed to automatically discover new plug-and-play (PnP) compatible hardware, and then configure the device, OS, and registry. Applications Programming Interface: The API allows programmers to create software applications consistent with the operating system. Open Graphics Library (OpenGL): Cross-platform standard specification for multimedia graphics. DirectX: Collection of API's related to multimedia tasks for Microsoft Windows. Additional Capabilities of an Operating System Almost all modern operating system can support more than one user, task, or CPU. Multi-user - A type of operating system that allows multiple users to access the operating system at the same time. Multitasking - A method a computer uses to share resources between multiple tasks, or process. Multiprocessing - A type of computer that can support more than one physical processor or the ability to schedule tasks between multiple CPU's. Multithreading - A method used by a CPU to process multiple threads, or tasks within a program, at the same time. Desktop Operating System - A desktop operating system is intended for use in a small office/home office (SOHO) with a limited number of users. A network operating system (NOS) is designed for a corporate environment serving multiple users with a wide range of needs. Characteristics of computer system: Designed to support a single user Designed to run single-user applications Designed to share files and folders on a small network Designed to share peripherals on a small network Network Operating System Characteristics of NOS: Designed to support multiple users Designed to run multi-user applications Designed to be robust and redundant Designed to be used on a network Designed with increased security compared to desktop operating systems Common tasks for a NOS: File Transfer Protocol (FTP) Simple Mall Transfer Protocol (SMTP) Hypertext Transfer Protocol (HTTP)Lightweight Directory Access Protocol (LDAP) Active Directory Network operating systems are designed to function well in a client/server environment A server is a robust computer that is used to service the needs of multiple clients within a network. Commonly used desktop operating systems fall into three group: Windows - Windows dominates the personal computer world, offering a graphical user interface (GUI), virtual memory management, multitasking, and support for many peripheral devices. Mac - Mac OS features a graphical user interface (GUI) that utilizes windows, icons, and all applications that run on a Macintosh computer have a similar user interface. Linux - Linux is a freely distributed open source operating system that runs on a number of hardware platforms. Operating systems have several similarities: GUI Interface Standard “look and feel” characteristics Multithreading capabilities Multitasking capabilities Ability to function with most hardware The code for an operating systems will be either open source or proprietary: Open source applications can be read and modified. Programmers openly share code with other programmers. Linux distributions are open source. Proprietary application cannot be read or modified. Proprietary software agreements restrict the use of the software, identifying where and when the software may be used. Attributes of NOS: A NOS has much of the same functionality as a desktop operating system. Determining the number of users that a server can support depends on factors such as the hardware specifications, the network operating system, and physical demands on the system. A NOS will normally remain stable when the number of users is high, but the process may become slow. The most common network operating systems include: Novell Netware Microsoft Windows Server Linux UNIX Determine operating system based on customer needs Select the proper operating system to meet the needs of your customer, gain as much information about the customer's daily activities as possible. Once you have a thorough understanding of what the customer needs, you can successfully select appropriate software and hardware to satisfy existing and future requirements. What Does Your Customer Require? To identify applications that customers will use and ensure compatibility When selecting hardware and software, the needs of your customer should come first. Remain neutral and listen to the needs of your customer before deciding on any computer hardware or software solution. Explore customer needs by asking the following types of questions: What general office applications, such as word processing, spreadsheets, or presentation software, does your customer require? What graphics, such as Photoshop or illustrator, does your customer require? What animation, such as Flash, does your customer require? What business applications, such as accounting, contact management, sales tracking or database, does your customer require? Once you have determined the types of software your customer requires, you should determine which available products will meet these needs. Before recommending applications, you should review the existing operating systems and software applications that your customer is using. The following are some of the factors to consider: Is compatibility an issue? Which operating system is required for current applications? Will the applications work with the existing hardware? Do any files have to be transferred between systems? Is there an issue with the format of the file systems involved? Are the applications standalone or networked? Identify Minimum Hardware Requirements Operating systems and applications have minimum hardware requirements that must be met for the computer to be functional. In some cases, the application requirements may exceed the requirements of the operating system. For the application to function properly, it will be necessary to satisfy any additional requirement. Meeting only the minimum requirements may not be beneficial to your customer in the long term. Your customer may need to upgrade or purchase additional hardware. Increasing the following are some common upgrades to the minimum requirements: RAM capacity Hard drive size Processor speed Video card memory and speed Identify the equipment that your customer has in place when you are analyzing hardware requirements. If upgrades are required to meet minimum requirements, conduct a cost analysis to determine the best course of action. In some cases, it may be necessary for the customer to purchase new equipment. In other cases, it may be cost-effective to upgrade the existing equipment. Hardware Compatibility List (HCL) - Most operating systems have a hardware compatibility list (HCL) that can be found on the manufacturer’s website. These lists provide a detailed inventory of hardware that has been tested and is known to work with the operating system. If the hardware already in place is not on the list, the hardware may require upgrading. If a hardware component is not on the list, there may be problems once installed. Lesson 3: Computer Hardware, Input, Process, Output, Storage And Network Computer Hardware - refers to the physical equipment or components of an electronic data processing. It is also composed of input, output and storage and network devices. Input Devices - Input devices are the hardware devices which take information from the user of the computer system, convert it into electrical signals and transmit it to the processor. Keyboard - A computer hardware that used to input text characters and other commands. Mouse - A device that used to point to and select items on your computer screen. Image Scanner - A Device that used to transfer images or text a computer there are special models the negatives or to scan book. Web Camera - It is low resolution video camera used to provide visual input. Microphone - Microphone is an input device to input sound that is then stored in a digital form. This is used to add sounds. Output Devices - It is used to present information to the user from a computer. Output devices take data from the computer system and convert it to a form that can be read by humans. Monitor - The most important difference between these monitor types is the technology used to create an image. Cathode-ray (CRT) - The most common monitor type, red, green, blue electron beams. Most tv’s used this technology. Liquid crystal display (LCD) - Is commonly used in laptops and some projectors. It consist of two polarizing filters with a liquid crystal solution. Digital light processing (DLP) - Is a technology used in projectors, DLP projectors use a spinning color wheel with a microprocessor controlled array of mirrors called a digital micromirror device (DMD). Printers And Fax Machines - Printers are output devices that create hard copies of computer files. Some printers specialize in particular applications. Speakers and Headphones - Speakers and headphones are output devices for audio. Storage Device - Alternatively referred to as digital storage, storage, storage media, or storage medium, a storage device is any hardware capable of holding information either temporarily or permanently. The picture shows an example of a drobo, an external secondary storage device. Magnetic storage device - Magnetic storage is one of the most common types of storage used with computers. Optical storage device - Another common storage device is this lasers and lights as its method of writing and reading data. Flash memory - Has started to replace magnetic media, it is more efficient and reliable. Paper storage - Early computers had no method of using any of the above technologies for storing information, these forms are rarely used. Network Devices: Repeater - It operates at the physical layer. Its job is to regenerate the signal over the same network. HUB - It is basically a multiport repeater. A hub connects multiple wires coming from different branches Types of HUB: Active Hub - These are the hubs which have their own power supply and can clean, boost an delay the signal along the network. Passive Hub - These are the hub which collect wiring from nodes and power supply from active hub. These hub relay signals onto network without cleaning and boosting. Bridge - It operates a data link layer. A bridge is a repeater, with add on functionality of filtering content by reading the MAC addresses of source and destination. It is used for interconnecting two LANS working on the same protocol. Types of Bridge: Transparent Bridge - These are the bridge in which the stations are completely unaware of the bridges existence. Source Routing Bridge - Source route bridging is used on token ring networks, and is standardized in Section 9 of the IEEE 802.2 standard. The operation of the bridge is simpler (spanning tree protocol is not necessary) and much of the bridging functions are performed by the end systems, particularly the sources, giving rise to its name. Switch - It is a multi port bridge with a buffer and a design that can boost can perform error, it divides collision domain of host. Routers - In order for devices on the network to connect to the Internet, the router must be connected to a modem. Therefore, most routers have a specific Ethernet port that is designed to connect to the Ethernet port. Gateway - It is a passage to connect two networks together that may work upon different networking models. Brouter - Also known as a bridging router which combines features of both bridge and router. It is working as a bridge, it can filter local area network traffic. Lesson 4: Motherboard and Computer Ports Motherboard - Mother Board (known as the Mainboard, system board, base board, planar board or logic board, or colloquially, a mobo). It holds and allows communication between many of the crucial electronic components of a system, such as the central processing unit (CPU) and memory, and provides connectors for other peripherals. Motherboard contains significant sub-systems such as the central processor, the chipset’s input/output and memory controllers, interface connectors, and other peripheral devices. Computer Ports - A computer port is a specialized outlet on a piece of equipment to which a plug or cable connects and ports serve as linkage between the computer to peripheral devices and other computers. Central Processing Unit (CPU) - The CPU (Known as the microprocessor or the processor) is serve as the computer’s brain and responsible for computations, fetching, decoding and executing program instructions. Processor Chip - The processor chip is identified by the processor type and the manufacturer. The information is from the manufacturer which is identify the processor that fits in the sockets. Random Access Memory (RAM) - Random Access Memory or RAM that stores dynamic data temporarily and the working place of the computer. The RAM serve place where data and active programs occur and it loses the contents once power is turned off or shutdown. Basic Input/Output Systems (BIOS) - The BIOS have all the codes required for controlling the keyboard. Displaying the screen, disk drives, serial communications, and a number of miscellaneous functions. BIOS is the link between the software and computer hardware. Cache Memory - A small block of high-speed memory that boosts the PC’s performance by pre-loading information from the (relatively slow) main memory and passing it to the processor on demand. Expansion Bus - Expansion bus is an input/output pathway to the peripheral devices coming from the CPU. It is typically made up of a peripheral devices coming from the CPU and signals such as data, memory, addresses, and power and control signals are carried from component to component by the busses. Other types of busses are ISA and EISA. Chipset - A chipset is a group of tiny circuits that coordinates the data flow back and forth from a computer’s key components. A chip is also the one that controls data flow to and from the hard disk and the devices that are connected to the channels of IDE. Switches and Jumpers - DIP (Dual In-Line Package) switches are small electronic switches found on the circuit board that can be turned on or off just like a normal switch. Jumper pins are small protruding pins on the mother board. A jumper cap or bridge is used to connect or short a pair of jumper pins. Jumper caps are metal that close an electrical circuit and sometimes used to configure expansion boards. By placing a jumper plug over a different set of pins, you can change a board’s parameters. Computer Port - Computer port is also called as a Communication Port as it is responsible for communication between the computer and its peripheral device. Communication ports can be divided into two types based on the type or protocol used for communication. They are Serial Ports and Parallel Ports. Serial Port is an interface through which peripherals can be connected using a serial protocol which involves the transmission of data one bit at a time over a single communication line. Common types of serial port is a DSubminiature or a D-sub connector that carry RS-232. Parallel port is an interface through which the communication between a computer and its peripheral device is in a parallel manner i.e. data is transferred in or out in parallel using more than one communication line or wire. Printer port is an example of parallel PS/2. PS/2 Connector - PS/2 connector is developed by IBM for connecting mouse and keyboard. P/S2 connectors are color coded as purple for keyboard and green for mouse and is has a 6-pin DIN Connector. This is a pinout diagram of PS/2 female connector even though the pinout of both mouse and keyboard PS/2 ports same, computers do not recognize the device when connected to wrong port. Serial Port - The term Serial Port is used to refer the interface that is compliant to RS-232 standard. There are two types of serial ports that are commonly found on a computer: DB25 and DE-9. DB-25 - Db-25 is a variant of D-sub connector and is the original port for RS-232 serial communication and rarely used as a serial port and often used as a parallel printer port as a replacement of the Centronics Parallel 36 pin connector. Parallel Port Or Centronics 36 Pin Port - Parallel port is an interface between computer and peripheral devices like printers with parallel communication. The Centronics ports is a 36-pin port that was developed as an interface for printers and scanners and hence a parallel ports is also called as a Centronics port. Audio Ports - Audio ports are used to connect speakers or other audio output devices with the computer. Surround Sound Connectors or 3.5 mm TRS Connector A 6-connector system included on majority of computers for audio out as well as a microphone connection. These 6 connectors can be used for a surround sound configurations of up to 8 channels. S/PDIF/TOSLINK - The Sony /Philips Digital Interface Format (S/PDIF) is an audio interconnect used in home media. It supports digital audio and can be transmitted using coaxial RCA Audio cable or an optical fiber TOSLINK connector. TOSLINK (Toshiba Link) is most frequently used digital audio port that can support 7.1 channel surround sound with just one cable. VGA Port - VGA (Video Graphics Array) it is a D-sub connector consisting of 15 pins in 3 rows. The connector is called as DE-15. It is the main interface between computers and older CRT monitors. Digital Video Interface - DVI is a high speed digital interface between a display controller like a computer and a display device like a monitor. IT was developed with an aim of transmitting a lossless digital video signals and replace by the analogue VGA technology. Mini DVI - Mini-DVI port is developed by Apple as an alternative to Mini-VGA port and is physically similar to one. It is smaller than regular DVI port. It is a 32-pin port and is capable of transmitting DVI, composite, S-Video and VGA signals with respective adapters. Micro-DVI - Micro-DVI port, as the name suggests is physically smaller than Mini-DVI and is capable of transmitting only digital signals. This port can be connected to external devices with DVI and VGA interface and respective adapters are required. Display Port - Display Port is a digital display interface with optimal multiple channel audio and other forms of data. Display Port is developed with an aim of replacing VGA and DVI ports as the main interface between monitor.Display Port has a 20-pin connector, which is very less number when compared to DVI port and offers better resolution. RCA Connector - RCA Connector can carry composite video and stereo audio signals over three cables. Composite or yellow colored RCA connector that transmits analogue video signals. The red and white connectors are used for stereo audio signals (red for right channels and white for left channel). S-Video - S-Video or separate Video connector is used for transmitting only video signals. The picture quality is better than that of composite. Out of the 4 pins, one pin is used to carry the intensity signals (black and white) and other pin is used carry color signals. HDMI - HDMI is an abbreviation of high Definition Media Interface. HDMI is a digital interface to connect High Definition and Ultra High Definition devices like Computer monitors, HDTVs, Blu-Ray players, gaming consoles, High Definition Cameras. The HDMI connector consists of 19 pins and the latest versions HDMI i.e. HDMI 2.0 can carry digital video signal up to a resolution of 4096X2160 and 32 audio channels. USB - Universal Serial Bus (USB) replaced serial ports, parallel ports PS/2 connectors, game ports and power charges for portable devices. There are three kinds of USB ports: Type A, Type B or mini USB and Micro USB. USB Type A - USB Type-A port is a 4-pin connector. There are different versions of type – A USB ports: USB 1.1, USB 2.0 and USB 3.00 USB 3.0 is the common standard and supports a data rate of 400MBps. USB 3.1 is also released and support a data rate up to 10Gbps. The USB 2.0 is black color coded and USB 3.0 is blue. RJ-45 - Ethernet is a networking technology that is used to connect your computer to internet and communicate with other computer or networking devices. The interface that is known as Registered Jack (RJ) and RJ – 45 port in particular is used for Ethernet over cable. RJ-45 connector is an 8 pin 0 8 contact (8P - 8C) type modular connector. The unkeyed 8p – 8C modular connector is generally referred to the Ethernet RJ-45. Often, RJ-45 ports are equipped with two LEDs for indication transmission and packet detection. RJ-11 - Rj-11 is another type of Registered Jack that is used as an interface for telephone, modem or ADSL connections. RJ-45 and RJ11 ports look alike but RJ-11 is a smaller port and uses a 6 point – 4 contact (6P – 4C) connector even though a 6 point – 2 contact (6P – 2C) is sufficient. E-SATA - e-SATA is an external ports capable of supporting both eSATA and USB. Neither the SATA organization nor the USB organization has officially approved the e-SATA and must be used at user’s risk. Power Supply - A power supply is a devices that supplies electric power to the components of the computer unit. Power Supply converts Alternating-Current(AC) Power into Direct-Current(DC). AC- alternating current comes from the outlet DC- direct current goes to the PC Electrons – A flow of negatively charged particles Called electrons ELECTRICITY: Volts - 110-115v in USA other countries use 220-230v(pressure) Ampheres - The number of electron per second flowing between two Points the amount of water per sec. Watts - Amount of power (Typical PC today use about 500 watts) Ohms - Resistance Impedance Lesson 5: Computer Power Supply PARTS OF A POWER SUPPLY a. Input voltage Selector – Allows you to choose which Source or input voltage you are to use (110v or 220v) b. Power plug receptacle – Connect the power supply to the main electricity supply via wall socket c. Power supply fan - Circulates air throughout the power Supply It acts as a cooling system to the power supply d. Cover - Simply providing structural support to the power supply and keeps dust e. Disk Drive Connectors - Connectors that are designed to be attached to the rear of each drive f. Motherboard Connector - Connects to the motherboard to provide power to the motherboard Processor, memory, chipset, integrated components and any card plugged into bus slots. Basic Components of a Power Supply: a. Transformer – it is a static device that transfer electrical energy from The primary winding to the secondary winding without affecting the frequency. b. Rectifier – it is a device used to change the ac power into dc. The basic rectifier is The diode. This diode is a unidirectional device that act as rectifier in the forward direction. 2 type of Power Supply Filters a. C-filter or Capacitance filter – is the simplest and most economical filter available b. RC-filter – is used to reduce the amount of ripple voltage across a capacitor filter Voltage Regulators - A voltage regulator is intended to give a very steady or well regulated DC output. It is always Best to have steady output voltages so that the load will function properly. Series voltage regulator - The series element controls the amount of the unregulated input voltage that goes to The output as a regulated output. Shunt voltage regulator - The shunt voltage regulator provides regulation by shunting current away from the load to Regulate the output voltage. IC Voltage Regulators - A regulator Integrated Circuit (IC) unit contains the circuitry the reference source, comparator Amplifier , control device, and the overload protector – inside a single IC. Power supply sample diagram: Color codes of power supply cables are as follow: 1.Black wires – those are used to provide a ground for the current. 2. Yellow wires – this is color denotes +12volt 3. Red Wires – this color denotes +5volt 4. Blue Wires - -12volt 5.White Wires - -5volt 6. Orange Wires – 3.3volt 7. Green Wires - Control wire to check dc voltage 8. Purple Wires - +5V on standby mode