Internal Components

RAID Levels

RAID provides a way to store data across multiple hard disks for redundancy.

Specialized Computer Systems

-CAD or CAM (CAx) workstation Powerful processor High-end video card Maximum RAM -Audio and video editing workstation Specialized audio card Specialized video card Large, fast hard drive Dual monitors -Virtualization workstation Maximum RAM Maximum CPU cores

Memory Modules

-Memory modules are memory chips that have been soldered on to a special circuit board for easy installation and removal. -Dual Inline Package (DIP) is an individual memory chip. -Single Inline Memory Module (SIMM) is a small circuit board that holds several memory chips. -Dual Inline Memory Module (DIMM) is a circuit board that holds SDRAM, DDR SDRAM, and DDR2 SDRAM chips. -RAM Bus Inline Memory Module (RIMM) is a circuit board that holds RDRAM chips. -Small Outline DIMM (SODIMM) is a smaller, more condensed version of DIMM which provides random access data storage that is ideal for use in laptops, printers, and other devices where conserving space is desirable. -The speed of memory has a direct impact on how much data a processor can process because faster memory improves the performance of the processor. As processor speed increases, memory speed must also increase.

Selecting a Motherboard (con't)

-Motherboards have different types of CPU sockets and CPU slots. This socket or slot provides the connection point and the electrical interface for the CPU. The CPU package must match the motherboard socket type or CPU slot type. A CPU package contains the CPU, connection points, and materials that surround the CPU and dissipate heat. -Data travels from one part of a computer to another through a collection of wires known as the bus. The bus has two parts. The data portion of the bus, known as the data bus, carries data between the computer components. The address portion, known as the address bus, carries the memory addresses of the locations where data is read or written by the CPU. -The bus size determines how much data can be transmitted at one time. A 32-bit bus transmits 32 bits of data at one time from the processor to RAM or to other motherboard components, while a 64-bit bus transmits 64 bits of data at one time. The speed at which data travels through the bus is determined by the clock speed, measured in MHz or GHz. -PCI expansion slots connect to a parallel bus, which sends multiple bits over multiple wires simultaneously. -PCI expansion slots are being replaced with PCIe expansion slots that connect to a serial bus, which sends one bit at a time at a faster rate. When building a computer, choose a motherboard that has slots to meet your current and future needs.

CPU Features & Classifications

-Multi-core processors - RAM is shared between the processors -Cache memory - L1, L2, and L3 -Speed of a processor - maximum speed without errors -Front Side Bus (FSB) - path between the CPU and chip set, expansion cards, and RAM -32-bit and 64-bit - number of instructions handled by the processor at one time

Selecting Solid State Drives

-Solid State Drives (SSD) use static RAM instead of magnetic platters to store data. -SSDs are highly reliable because they have no moving parts. -Considerations when selecting: Cost Internal or external Case location System compatibility Power requirements Speed Capacity

Small Computer Systems Interface (SCSI)

-Usually used for hard drives and for tape storage . -Ideal for high-end computers, including network servers that require high transfer speeds and reliability. -SCSI devices are connected in a series, forming a chain that is called a daisy chain. -Each end of the daisy chain is terminated to prevent signal reflections and interference. -Each device must have a unique SCSI ID.

Selecting Case Fan

Case fan considerations: - Case size - Fan speed - Number of components in the case - Physical environment - Number of mounting places available - Location of mounting places available - Electrical connections

Selecting Heat Sink/Fan

Heat sink/fan assembly considerations: -Socket type -Motherboard physical specifications -Case size -Physical environment

Input Devices

Input devices are used to enter data or instructions into a computer:

Storage Drives (con't)

- A storage drive reads or writes information to magnetic storage media. -The drive can be used to store data permanently or to retrieve information from a media disk. Some storage drives can connect to the computer using a USB port, a FireWire port, or an SCSI port. These portable storage drives are sometimes referred to as removable drives and can be used on multiple computers. -A floppy drive is usually configured as the A: drive. The floppy drive can be used to boot the computer if it contains a bootable floppy disk. -A hard drive is usually configured as the C: drive and contains the operating system and applications. The hard drive is usually configured as the first drive in the boot sequence. The speed of a hard drive is measured in revolutions per minute (RPM). Multiple hard drives can be added to increase storage capacity. -SSDs use memory chips to manage all data in storage.

Output Devices: Monitors and Projectors

- Cathode-ray tube (CRT) has three electron beams. Each beam directs colored phosphor on the screen that glows either red, blue, or green. -Liquid crystal display (LCD) is commonly used in laptops and some projectors. LCD comes in two forms, active matrix and passive matrix. -A light-emitting diode (LED) display is an LCD display that uses LED backlighting to light the display. -An Organic LED (OLED) display uses a layer of organic material that responds to electrical stimulus to emit light.

Cooling Systems

- Electronic components generate heat. Too much heat can damage components. - A case fan makes the cooling process more efficient. - A heat sink draws heat away from the core of the CPU. A fan on top of the heat sink moves the heat away from the CPU. Fans can be dedicated to cool the Graphics-processing unit (GPU).

Cooling Systems (con't)

- Heat is caused by the flow of current within the components. Computer components perform better when kept cool. If the heat is not removed, the computer may run slower. If too much heat builds up, computer components can be damaged. - Increasing the air flow in the computer case allows more heat to be removed. Other components are also susceptible to heat damage and are sometimes equipped with fans. Video adapter cards also produce a great deal of heat. - Computers with extremely fast CPUs and GPUs may use a water-cooling system. A metal plate is placed over the processor and water is pumped over the top to collect the heat that the CPU creates. The water is pumped to a radiator to be cooled by the air, and then re-circulated.

Ports and Cables (con't)

-A SCSI port can transmit data at rates in excess of 320 Mbps and can support up to 15 devices. SCSI devices must be terminated at the endpoints of the SCSI chain. A network port, also known as an RJ-45 port, connects a computer to a network. The maximum length of network cable is 328 feet (100 m). -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. -An audio port connects audio devices to the computer. -A video port connects a monitor cable to a computer. Network Ports and Cables - The connection speed depends on the type of network port. Standard Ethernet can transmit up to 10 Mbps, Fast Ethernet can transmit up to 100 Mbps, and Gigabit Ethernet can transmit up to 1000 Mbps. The maximum length of network cable is 328 feet (100 m). -PS/2 Ports - The connectors for the keyboard and mouse are often colored differently. If the ports are not color-coded, look for a small figure of a mouse or keyboard next to each port. Audio Ports The following audio ports are commonly used: Line In - Connects to an external source, such as a stereo system Microphone - Connects to a microphone Line Out - Connects to speakers or headphones Gameport/MIDI - Connects to a joystick or MIDI-interfaced device

Optical Drives, Flash Drives and Drive Interfaces

-An optical drive is a storage device that uses lasers to read data on the optical media. The three types are CD, DVD, and BD (Blu-ray). -A flash drive is a removable storage device that connects to a USB port. A flash drive uses a type of memory that requires no power to maintain the data. Common drive interfaces are: Integrated Drive Electronics (IDE) Enhanced Integrated Drive Electronics (EIDE) Parallel ATA (PATA) Serial ATA (SATA) and External SATA (eSATA) Small Computer System Interface (SCSI)

Selecting Case and Power Supply

-Determine the customer's needs before making any purchases or performing upgrades. -A power supply should support 25 percent more wattage than all the attached components require. -The computer case holds the power supply, motherboard, memory, and other components. -When purchasing a new computer case and power supply separately, ensure that all of the components will fit into the new case and that the power supply is powerful enough to operate all of the components.

Memory Modules (con't)

-Early computers had RAM installed on the motherboard as individual chips. The individual memory chips, called dual inline package (DIP) chips, were difficult to install and often became loose on the motherboard. Memory modules solved this problem. NOTE: Memory modules can be single-sided or double-sided. Single-sided memory modules only contain RAM on one side of the module. Double-sided memory modules contain RAM on both sides of the module. -Single-channel memory is capable of transferring data at 64 bits. Dual-channel memory increases speed by using a second channel of memory, creating a data transfer rate of 128 bits. -Double Data Rate (DDR) technology doubles the maximum bandwidth of SDRAM. DDR2 offers faster performance while using less energy. DDR3 operates at even higher speeds than DDR2; however, none of these DDR technologies are backward- or forward-compatible.

Selecting External Storage

-External storage connects to an external port such as a USB, IEEE 1394, SCSI, or eSATA. -Considerations when selecting: Port type Storage capacity Speed Portability Power requirements

Selecting Input and Output Devices

-FireWire (IEEE 1394) - Transfers data at 100, 200, or 400 Mbps and IEEE 1394b at 800 Mbps. -Parallel (IEEE 1284) - Transfers data at a maximum speed of 3 MBps. -Serial (RS-232) - Early versions were limited to 20 Kbps, but newer versions can reach transfer rates of 1.5 Mbps. -SCSI (Ultra-320 SCSI) - Connects as many as 15 devices with a transfer rate of 320 MBps. -USB interface is widespread and used with many different devices. USB (1.1) , USB 2.0 and USB 3.0. -SATA interface is replacing IDE and EIDE as the standard interface for hard drives. The eSATA (external SATA) connection can be hot-swappable

Specialized Computer Systems

-Gaming PC Powerful processor High-end video card High-end sound card High-end cooling Large amounts of fast RAM Fast storage Gaming-specific hardware -Home Theater Personal Computer (HTPC) Specialized cases and power supplies Surround sound audio HDMI output TV tuners and cable cards Specialized hard drive

Ports and Cables (con't)

-Input/output (I/O) ports on a computer connect peripheral devices, such as printers, scanners, and portable drives. -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. To connect a serial device, such as a modem or printer, a serial cable must be used. -A telephone cable (Rj11) is used to connect a modem to a telephone outlet. This cable uses an RJ-11 connector. A setup of an external modem uses a serial cable and a telephone cable. USB Ports and Cables - The Universal Serial Bus (USB) is a standard interface that connects peripheral devices to a computer. It was originally designed to replace serial and parallel connections. USB devices are hot-swappable, which means that users can connect and disconnect the devices while the computer is powered on. USB connections can be found on computers, cameras, printers, scanners, storage devices, and many other electronic devices. A USB hub is used to connect multiple USB devices. - USB 1.1 allows transmission rates of up to 12 Mbps in full-speed mode. USB 2.0 allows transmission speeds up to 480 Mbps. USB 3.0 allows transmission speeds of 4.8 Gbps. Is backward compatible. -FireWire Ports and Cables - FireWire uses the IEEE 1394 standard and is also known as i.Link. The IEEE 1394a standard supports data rates up to 400 Mbps. The IEEE 1394b standard supports data rates in excess of 800 Mbps. Parallel Ports and Cables - Parallel ports use the IEEE 1284 standard. To connect a parallel device, such as a printer, a parallel cable must be used. -SCSI Ports and Cables - A SCSI port can transmit data at rates in excess of 320 Mbps and can support up to 15 devices. Check the device manual for termination procedures. Some SCSI connectors resemble parallel connectors. Be careful not to connect the cable to the wrong port. The voltage used in the SCSI format may damage the parallel interface. SCSI connectors should be clearly labeled.

Selecting Media Readers

-Media Reader -device that reads and writes to different types of media cards, found in a digital camera, smart phone, or MP3 player. -Considerations when selecting: Internal or external Type of connector used Type of media cards supported

Error Checking

-Memory errors occur when the data is not stored correctly in the RAM chips. -The computer uses different methods to detect and correct data errors in memory: Nonparity Parity ECC

Names of Input Devices

-Mouse and Keyboard -KVM switch -Gamepad and joystick -Digital camera and digital video camera -Biometric authentication device -Touch screen -Scanner

Adapter Cards (con't)

-NIC - Connects computer to a network using a network cable -Wireless NIC - Connects computer to a network using radio frequencies -Sound adapter - Provides audio capability -Video adapter - Provides graphic capability -Modem adapter - Connects a computer to the Internet using a phone line -USB port - Connects a computer to peripheral devices -Parallel port - Connects a computer to peripheral devices -Serial port - Connects a computer to peripheral devices Computers have expansion slots on the motherboard to install adapter cards. The type of adapter card connector must match the expansion slot. A riser card was used in computer systems with the LPX form factor to allow adapter cards to be installed horizontally. The riser card was mainly used in slim-line desktop computers. The different types of expansion slots are: -Peripheral Component Interconnect (PCI) is a 32-bit or 64-bit expansion slot. PCI is the standard slot currently used in most computers. -Advanced Graphics Port (AGP) is a 32-bit expansion slot. AGP is designed for video adapters. PCI-Express is a serial bus expansion slot. PCI-Express is backward compatible with PCI parallel slot. PCI-Express has x1, x4, x8, and x16 slots.

Selecting RAM

-New RAM may be needed when an application locks up or the computer displays frequent error messages -When selecting new RAM, check the compatibility with the current motherboard. -The speed of the new RAM must be the same or faster than the existing RAM.

Hard Drive Connectors

-PATA (Parallel ATA) hard drives -Originally, called ATA (Advanced Technology Attachment). With the introduction of SATA, ATA was renamed to PATA. -Can use a 40-pin / 80-conductor cable or a 40-pin / 40-conductor cable. -SATA (Serial ATA) hard drives -Connect to the motherboard using a serial interface. -Have a higher data-transfer rate than PATA drives. -Smaller data cable allows for improved airflow. -eSATA external SATA -SCSI (Small Computer Systems Interface) hard drives use a 50-pin, 68-pin, or 80-pin connector. -Up to 15 SCSI drives can be connected to a SCSI drive controller.

Output Devices

-Printers and Fax Machines are output devices that create hard copies of computer files. -Scanners create electronic file versions of paper documents. -Speakers and headphones are output devices for reproducing audio signals.

Selecting a CPU

-Replace the CPU when it fails or is no longer adequate for the current applications. -Make sure the CPU is compatible with the existing motherboard: -The new CPU must use the same socket type or slot type and chip set. -The BIOS must support the new CPU. -The new CPU may require a different heat sink/fan assembly. -Make sure the correct voltage is maintained. -Use manufacturers' websites to investigate the compatibility between CPUs and other devices.

Cache

-SRAM is used as cache memory to store the most frequently used data. -SRAM provides the processor with faster access to the data than retrieving it from the slower DRAM, or main memory.

Ports and Cables

-Serial ports transmit one bit of data at a time. -A telephone cable (RJ11) is used to connect a modem to a telephone outlet. -USB is a standard interface for connecting hot-swappable peripheral devices to a computer. Some devices can also be powered through the USB port. -FireWire is a high-speed, hot-swappable interface that can support up to 63 devices. Some devices can also be powered through the FireWire port. -A parallel cable is used to connect parallel devices, such as a printer or scanner, and can transmit 8 bits of data at one time.

CPU

-Some CPUs incorporate hyperthreading or hypertransport to enhance the performance of the CPU. - The amount of data that a CPU can process at one time depends on the size of the processor data bus. -Speed of the CPU is measured in cycles per second-megahertz (MHz) or gigahertz (GHz). - Overclocking is a technique used to make a processor work at a faster speed than its original specification.

Storage Drives

-Storage drives read or write information to magnetic storage media. -They may be fixed or removable. -The hard disk drive (HDD) is a magnetic storage device. The storage capacity is measured in gigabytes (GB) or terabytes (TB) -Magnetic hard drives have drive motors designed to spin magnetic platters and move the drive heads. -Solid state drives (SSDs) do not have moving parts, which results in faster access to data, higher reliability, reduced power usage. -A floppy disk drive (FDD) is storage device that uses removable 3.5 inch floppy disks that can store up to 1.44 MB of data.

Motherboard Form Factor

-The form factor of motherboards pertains to the size and shape of the board. -It also describes the physical layout of the different components and devices on the motherboard. -Various form factors exist for motherboards.

Selecting a Motherboard

-When selecting a replacement motherboard, make sure it supports the CPU, RAM, video adapter, and other adapter cards. -The socket and chip set on the motherboard must be compatible with the CPU. -The motherboard must accommodate the existing heat sink/fan assembly. -The existing power supply must have connections that fit the new motherboard. -The number and type of expansion slots must match the existing adapter cards. -The new motherboard must physically fit into the current computer case.

CPU (Con't)

-With hyperthreading, the CPU has multiple pieces of code being executed simultaneously on each pipeline. To an operating system, a single CPU with hyperthreading appears to be two CPUs. - The speed of a CPU is rated in cycles per second. The speed of current CPUs is measured in millions of cycles per second, called megahertz (MHz), or billions of cycles per second, called gigahertz (GHz). This is also called the CPU bus or the front side bus (FSB). The wider the processor data bus width, the more powerful the processor is. Current processors have a 32-bit or a 64-bit processor data bus. -Overclocking is not a reliable way to improve computer performance and can result in damaging the CPU. 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 instruction set.

Video Ports and Cables

A video port connects a monitor cable to a computer. Video ports and connector types: -DVI, Displayport, RCA, DB-15, BNC, RJ-45, MiniHDMI, Din-6 Display cables transfer video signals from the computer to display devices. Display cable types: -High-Definition Multimedia Interface (HDMI), DVI, Video Graphics Array (VGA), Component/RGB, Composite, S-Video, Coaxial, Ethernet,

Selecting Adapter Cards

Adapter (or expansion) cards add extra functionality to a computer. Before purchasing an adapter card, check: -Is there an open expansion slot? -Is the adapter card compatible with the open slot? -What are the customer's current and future needs? -What are the possible configuration options? If the motherboard does not have compatible expansion slots, external devices are an option: -Are USB or FireWire versions of the external device available? -Does the computer have an open USB or FireWire port?

Adapter Cards

Adapter cards increase the functionality of a computer by adding controllers for specific devices or by replacing malfunctioning ports. - Examples of adapter cards: Sound adapter and video adapter USB, parallel, and serial ports Network Interface Card (NIC), wireless NIC, and modem adapter -Types of expansion slots: Peripheral Component Interconnect (PCI) Advanced Graphics Port (AGP) PCI-Express Mini PCI (laptops)

Selecting Optical Drives

An optical drive uses a laser to read and write data to and from optical media. -CD-ROM drive can only read CDs. -CD-RW can read and write to CDs. - DVD-ROM drive can only read DVDs and CDs -DVD-RW can read and write to DVDs and CDs. DVDs hold significantly more data than CDs -A Blu-ray reader (BD-R) can only read Blu-ray Discs, DVDs, and CDs. -A Blu-ray writer (BD-RE) can read and write to Blu-ray Discs and DVDs. Blu-ray Discs hold significantly more data than DVDs.

CPU

Brain of computer. - The CPU executes a program, which is a sequence of stored instructions. -Two major CPU architectures related to instruction sets: -Reduced Instruction Set Computer (RISC) - Complex Instruction Set Computer (CISC)

Optical Drives, Flash Drives and Drive Interfaces (con't)

CD, DVD, and BD (Blu-ray) media can be pre-recorded (read-only), recordable (write once), or re-recordable (read and write multiple times). CDs have a data storage capacity of approximately 700 MB. DVDs have a data storage capacity of approximately 4.3 GB on a single-layer disc, and approximately 8.5 GB on a dual-layer disc. BDs have a storage capacity of 25 GB on a single-layer disc, and 50 GB on a dual-layer disc. -An external flash drive, also known as a thumb 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: -IDE - Integrated Drive Electronics, also called Advanced Technology Attachment (ATA) is an early drive controller interface that connects computers and hard disk drives. -EIDE - Enhanced Integrated Drive Electronics, also called ATA-2, is an updated version of the IDE drive controller interface. -PATA - Parallel ATA refers to the parallel version of the ATA drive controller interface. -SATA - Serial ATA refers to the serial version of the ATA drive controller interface. -eSATA - External Serial ATA provides a hot-swappable, external interface for SATA drives. -SCSI - Small Computer System Interface is a drive controller interface that can connect up to 15 drives. -SCSI can connect both internal and external drives.

Selecting Media Readers (con't)

Common media cards: -Secure digital (SD) - SD cards were designed for use in portable devices such as cameras, MP3 players, and tablets. SD cards can hold as much as 4 GB. SD High Capacity (SDHC) cards can hold as much as 32 GB, while SD Extended Capacity (SDXC) cards can hold as much as 2 TB of data. -microSD - A much smaller version of SD, commonly used in cellular phones. CompactFlash - CompactFlash is an older format, but still in wide use because of its high capacity (up to 128 GB is common) and high speed. CompactFlash is often used as storage for video cameras. Memory Stick - A proprietary flash memory created by Sony Corporation. Memory Stick is used in cameras, MP3 players, hand-held video game systems, mobile phones, cameras, and other portable electronics.

Motherboard

Contains buses, electrical pathways in computers. Buses allow data to travel among various components. Accommodates CPU, RAM, expansion slots, heat sink/fan assembly, BIOS chip, chip set, socket, internal & external connectors, various ports, & the embedded wires that interconnect the motherboard components. -A motherboard is also known as the system board, the backplane, or the main board. Sockets, internal and external connectors, and various ports are also placed on the motherboard.

Internal Cables (con't)

Drives require both a power cable and a data cable. A power supply will have a SATA power connector for SATA drives, a Molex power connector for PATA drives, and a Berg 4-pin connector for floppy drives. The buttons and the LED lights on the front of the case connect to the motherboard with the front panel cables. Data cables connect drives to the drive controller, which is located on an adapter card or on the motherboard. NOTE: A colored stripe on a floppy or PATA cable identifies Pin 1 on the cable. When installing a data cable, always ensure that Pin 1 on the cable aligns with Pin 1 on the drive or drive controller. Some cables may be keyed and therefore they can only be connected one way to the drive and drive controller.

Display Cables

High-Definition Multimedia Interface (HDMI) - Carries digital video and digital audio signals. Digital signals provide high-quality video and high resolutions. -DVI - Carries analog, digital, or both analog and digital video signals. -Video Graphics Array (VGA) - Carries analog video signals. Analog video is low quality and can be interfered with by electrical and radio signals. -Component/RGB - Carries analog video signals over three shielded cables. -Composite - Carries analog audio or video signals. -S-Video - Carries analog video signals. -Coaxial - Carries analog, digital, or both analog and digital video or audio signals. -Ethernet - Carries analog, digital, or both analog and digital video or audio signals. Ethernet can also carry power.

Error Checking (con't)

Memory errors occur when the data is not stored correctly in the RAM chips. The computer uses different methods to detect and correct data errors in memory. Three different methods of memory error checking are: -Nonparity memory does not check for errors in memory. -Parity memory contains eight bits for data and one bit for error checking. The error-checking bit is called the parity bit. -Error Correction Code (ECC) memory can detect multiple bit errors in memory and correct single bit errors in memory.

Monitors and Projectors (con't)

Monitors and projectors are primary output devices for a computer. The most important difference between these monitor types is the technology used to create an image: CRT - The cathode-ray tube (CRT) has three electron beams. Each beam directs colored phosphor on the screen that glows either red, blue, or green. Areas not struck by an electron beam do not glow. The combination of glowing and non-glowing areas creates the image on the screen. LCD - It consists of two polarizing filters with a liquid crystal solution between them. An electronic current aligns the crystals so that light can either pass through or not pass through. The effect of light passing through in certain areas and not in others is what creates the image. A light-emitting diode (LED) display is an LCD display that uses LED backlighting to light the display. DLP - DLP projectors use a spinning color wheel with a microprocessor-controlled array of mirrors called a digital micromirror device (DMD). OLED - An organic LED display uses a layer of organic material that responds to electrical stimulus to emit light. Plasma - Plasma displays are another type of flat panel monitor.

Monitors and Projectors

Plasma - Plasma displays are another type of flat panel monitor -Digital light processing (DLP) is a technology used in projectors. -Monitor Resolution refers to the level of image detail that can be reproduced. Higher resolution settings produce better image quality. Several factors are involved in Monitor Resolution -Pixel, Dot Pitch, Contrast Ratio, Refresh rate, Interlace/Non-Interlace, Horizontal vertical color, Aspect ratio, Native resolution

Internal Cables

Power supply connectors- SATA, Molex, and Berg. -Front panel cables connect the case buttons and lights to the motherboard. -Data cables connect drives to the drive controller. -Floppy disk drive (FDD) data cable -PATA (IDE) data cable (40 conductor) -PATA (EIDE) data cable (80 conductor) -SATA data cable -SCSI data cable

Output Speakers (con't)

Printers, Scanners, and Fax Machines - Some printers specialize in particular applications, such as printing color photographs. Other all-in-one type printers are designed to provide multiple services such as printing, fax, and copier functions. Speakers and Headphones - Most computers have audio support either integrated into the motherboard or on an adapter card. Audio support includes ports that allow input and output of audio signals. The audio card has an amplifier to power headphones and external speakers.

RAM

Random-access memory (RAM) -RAM is temporary storage for data and programs that are being accessed by the CPU. -RAM is volatile memory, which means that the contents are erased when the computer is powered off. -More RAM means more capacity to hold and process large programs and files, as well as enhance system performance.

ROM

Read-only memory (ROM) -Basic instructions for booting the computer and loading the operating system are stored in ROM. -ROM chips retain their contents even when the computer is powered down. - Read-only memory (ROM) chips are located on the motherboard. ROM chips contain instructions that can be directly accessed by the CPU. ROM chips retain their contents even when the computer is powered down. The contents cannot be erased or changed by normal means. ROM is sometimes called firmware. This is misleading because firmware is actually the software that is stored in a ROM chip.

Cache (con't)

SRAM is used as cache memory to store the most frequently used data. SRAM provides the processor with faster access to the data than retrieving it from the slower DRAM, or main memory. The three types of cache memory are: -L1 cache is internal cache and is integrated into the CPU. -L2 cache is external cache and was originally mounted on the motherboard near the CPU. L2 cache is now integrated into the CPU. -L3 cache is used on some high-end workstations and server CPUs.

Motherboard Form Factor (con't)

The form factor determines how individual components attach to the motherboard and the shape of the computer case. Various form factors exist for motherboards. -The most common form factor in desktop computers was the AT, based on the IBM AT motherboard. The AT motherboard can be up to approximately one foot wide. This cumbersome size led to the development of smaller form factors. The placement of heat sinks and fans often interferes with the use of expansion slots in smaller form factors. -A newer motherboard form factor, ATX, improved on the AT design. Some manufacturers have proprietary form factors based on the ATX design. This causes some motherboards, power supplies, and other components to be incompatible with standard ATX cases. -The chip set is composed of various integrated circuits attached to the motherboard that control how system hardware interacts with the CPU and motherboard. The CPU is installed into a slot or socket on the motherboard. The socket on the motherboard determines the type of CPU that can be installed. -The chipset of a motherboard allows the CPU to communicate and interact with the other components of the computer, and to exchange data with system memory, or RAM, hard disk drives, video cards, and other output devices. Most chipsets are divided into two distinct components, Northbridge and Southbridge. -Northbridge controls access to the RAM, video card, and the speeds at which the CPU can communicate with them. The video card is sometimes integrated into the Northbridge. -Southbridge , in most cases, allows the CPU to communicate with the hard drive, sound card, USB ports, and other I/O ports.

CPU

The latest processor technology has resulted in CPU manufacturers finding ways to incorporate more than one CPU core onto a single chip. Many CPUs are capable of processing multiple instructions concurrently: - Single Core CPU - One core inside a single CPU chip that handles all of the processing capability. A motherboard manufacturer may provide sockets for more than one single processor, providing the ability 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. - Triple Core CPU - Three cores inside a single CPU that is actually a quad-core processor with one of the cores disabled. - Quad Core CPU - Four cores inside a single CPU in which all cores can process information simultaneously for enhanced software applications. - Hexa-Core CPU - Six cores inside a single CPU - Octa-Core CPU - Eight cores inside a single CPU

Characteristics of input devices

The mouse and keyboard are the two most commonly used input devices. The mouse is used to navigate the graphical user interface (GUI). The keyboard is used to enter text commands that control the computer. -A keyboard, video, mouse (KVM) switch is a hardware device that can be used to control more than one computer using a single keyboard, monitor, and mouse. KVM switches provide cost-efficient access to multiple servers using a single keyboard, monitor, and mouse for businesses. Home users can save space using a KVM switch to connect multiple computers to one keyboard, monitor, and mouse. -Gamepad and Joystick-Gamepads allow the player to control movement and views with small sticks moved by the player's thumbs. Joysticks are also used to play games and run simulations Digital cameras and digital video cameras create images that can be stored on magnetic media. The image is stored as a file that can be displayed, printed, or altered. -Biometric identification makes use of features that are unique to an individual user, such as fingerprints, voice recognition, or a retinal scan. -A touch screen has a pressure-sensitive transparent panel. The computer receives instructions specific to the place on the screen that the user touches. -A scanner digitizes an image or document. The digitization of the image is stored as a file that can be displayed, printed, or altered. A bar code reader is a type of scanner that reads universal product code (UPC) bar codes. It is widely used for pricing and inventory information.

Selecting Hard Drives and Floppy Drives

The signs that a hard drive is failing and should be replaced as soon as possible: -Unusual noises -Error messages -Corrupt data or applications Replacement options: -Solid State Drives -Optical Drives -External Storage -Hard Drive -Floppy Disk Drive (limited use)

Monitor Characteristics

There are several factors that affect image quality: Pixels - The term pixel is an abbreviation for picture element. Pixels are the tiny dots that comprise a screen. Each pixel consists of red, green, and blue. Dot Pitch - Dot pitch is the distance between pixels on the screen. A lower dot pitch number produces a better image. Contrast ratio - The contrast ratio is a measurement of the difference in intensity of light between the brightest point (white) and the darkest point (black). A 10,000:1 contrast ratio shows dimmer whites and lighter blacks than a monitor with a contrast ratio of 1,000,000:1. Refresh Rate - The refresh rate is how often per second the image is rebuilt. A higher refresh rate produces a better image and reduces the level of flicker. Interlace/Non-Interlace - Interlaced monitors create the image by scanning the screen two times. The first scan covers the odd lines, top to bottom, and the second scan covers the even lines. Non-interlaced monitors create the image by scanning the screen, one line at a time from top to bottom. Most CRT monitors today are non-interlaced. Horizontal Vertical Colors (HVC) - The number of pixels in a line is the horizontal resolution. The number of lines in a screen is the vertical resolution. The number of colors that can be reproduced is the color resolution. Aspect Ratio - Aspect ratio is the horizontal to vertical measurement of the viewing area of a monitor. For example, a 4:3 aspect ratio would apply to a viewing area that is 16 inches wide by 12 inches high. A 4:3 aspect radio would also apply to a viewing area that is 24 inches wide by 18 inches high. A viewing area that is 22 inches wide by 12 inches high has an aspect ratio of 11:6. Native resolution - Native resolution is the number of pixels that a monitor has. A monitor with a resolution of 1280 x 1024 has 1280 horizontal pixels and 1024 vertical pixels. Native mode is when the image sent to the monitor matches the native resolution of the monitor. Monitors have controls for adjusting the quality of the image. Here are some common monitor settings: Brightness - Intensity of the image Contrast - Ratio of light to dark Position - Vertical and horizontal location of the image on the screen Reset - Returns the monitor settings to factory settings

Selecting Adapter Cards (con't)

There are several factors to consider when purchasing a new graphics card: -Slot type -Port type -Amount and speed of video RAM (VRAM) -Graphics processor unit (GPU) -Maximum resolution

Video Connectors

There are several video connector types: -Video Graphics Array (VGA) - VGA has a 3-row 15-pin female connector and provides analog output to a monitor. -Digital Visual Interface (DVI) - DVI has a 24-pin female connector or a 29-pin female connector and provides a compressed digital output to a monitor. DVI-I provides both analog and digital signals. DVI-D provides digital signals only. -High-Definition Multimedia Interface (HDMI) - HDMI has a 19-pin connector and provides digital video and digital audio signals. -S-Video - S-Video has a 4-pin connector and provides analog video signals. -Component/RGB - RGB has three shielded cables (red, green, blue) with RCA jacks and provides analog video signals.

RAID Levels (con't)

To the operating system, RAID appears as one logical disk. There are several different RAID levels. The following terms describe how RAID stores data on the various disks: Parity - A method used to detect data errors. Striping - A method used to write data across multiple drives. Mirroring - A method of storing duplicate data to a second drive.

Selecting Heat Sink/Fan and Case Fan

When choosing a heat sink or fan, there are several factors to consider: Socket type - The heat sink or fan type must match the socket type of the motherboard. Motherboard physical specifications - The heat sink or fan must not interfere with any components attached to the motherboard. Case size - The heat sink or fan must fit within the case. Physical environment - The heat sink or fan must be able to disperse enough heat to keep the CPU cool in warm environments. Fan speed - Larger fans spin more slowly than smaller fans, which reduces fan noise. Number of components in the case - Multiple components in a computer create additional heat, which requires more fans, larger fans, or faster fans. Physical environment - The case fans must be able to disperse enough heat to keep the interior of the case cool. Number of mounting places available - Different cases have different numbers of mounting places for fans. Location of mounting places available - Different cases have different locations for mounting fans. Electrical connections - Some case fans are connected directly to the motherboard, while others are connected directly to the power supply.