CH1 Internal PC Components 3

Newer KVM switches have the capability to share USB devices and speakers with multiple computers. Typically, by pressing a button on the KVM switch, the user can change the control from one connected computer to another connected computer. Some models of the switch transfer control from one computer to another using a specific key sequence on a keyboard, such as Ctrl > Ctrl > A > Enter to control the first computer connected to the switch, and then Ctrl > Ctrl > B > Enter to transfer control to the next computer.

Storage Device Interfaces and RAID

Internal HDDs, SSDs, and optical drives often connect to the motherboard using Serial AT Attachment (SATA) connections. SATA drives connect to the motherboard using a SATA 7-pin data connector.

At one end of the cable, the connector is keyed for the drive and the opposite end is keyed for the drive controller

3 versions of SATA

SATA 1

SATA 2

SATA 3

SATA 1 allows for a maximum data transfer rate of 1.5 Gb/s

SATA 2 can reach up to 3 Gb/s

SATA 3 is the fastest with speeds up to 6 Gb/s.

The cables and connectors are the same, but the data transfer speeds are different.

Legacy internal drive connection methods include Integrated Drive Electronics (IDE), Enhanced Integrated Drive Electronics (EIDE), and Parallel ATA.

Storage devices can also connect externally to the computer

USB has become the most common way to connect external devices. External SATA (eSATA) is another way to connect external storage devices. eSATA cables and connectors have a different shape than SATA cables and connectors.

USB 3.0 and USB 3.1 are blue in color and have become popular for connecting external storage devices because of fast transmission rates.

USB drives are also hot-swappable, which means that there is no need to reboot a computer when adding or removing a drive.

A single USB port in a computer can theoretically support up to 127 separate devices with the use of USB hubs.

A USB hub connects multiple USB devices. Finally, many devices can be powered through the USB port, eliminating the need for an external power source.

types of USB connectors.

USB Type A.

usb type b

usb micro b

USB Mini B

newest usb connector

usb type c

looks like usb micro b

regular pc usb

d shaped usb

commonly used for phones

Raid

Storage devices can also be grouped and managed to create large storage spaces with redundancy. To do so, computers can implement a redundant array of independent disks (RAID) technology. RAID provides a way to store data across multiple hard disks for redundancy and/or performance improvement. To the operating system, a RAID array appears as one disk.

how RAID stores data on the various disks:

Striping - Writes data across multiple drives.

Mirroring - Stores duplicate data on a second drive.

Parity - Detects data errors.

lvl0

lvl 1

lvl 2

lvl 3

lvl 4

lvl 5

data striping without redundancy

disk mirroring

error- correcting coding

no longer used

byte- level data striping with dedicated parity

block-lvl data striping with dedicated parity

combination of data striping and parity

highest peformance but not data protection, failure of one drive results in all loss of data

high performance, high data protection because all data is duplicated

same performance can be achieved lower cost using raid 3

for large sequential data requests

does not support multiple, simultaneous read and write requests

supports multiple read requests, if a disk fails the dedicated parity disk is used to create a replacement disk

block - level data striping with dedicated parity

supports multiple simultaneous reads and writes. data is written across all drives with parity

write performance is slower than raid 0 and 1

A video port connects a monitor to a computer using a cable. Video ports and monitor cables transfer analog signals, digital signals, or both.

Computers are digital devices that create digital signals. The digital signals are sent to the graphics card where they are transmitted through a cable to a digital display. Digital signals can also be converted to analog signals by the graphics card and transferred to an analog display.

Video Ports and Cables

Din-6

BNC connector

RCA connectors

VGA connector

Thunderbolt

HDMI

Mini DisplayPort

DisplayPort connector

Digital Visual Interface (DVI)

Wireless – These typically have additional transmitters to be connected to an external monitor / TV.

The DVI connector is usually white and consists of 24 pins (three rows of eight pins) for digital signals, 4 pins for analog signals, and a flat pin called a ground bar. Specifically, DVI-D handles digital signals only, while DVI-A handles only analog signals. DVI uses a dual-link interface which creates two groups of data channels that can carry more than 10 Gb/s of digital video information.

DisplayPort is an interface technology that is designed to connect high-end graphics-capable PCs and displays, as well as home theater equipment and displays. The connector consists of 20 pins and can be used for audio, video, or both. DisplayPort supports video data rates up to 8.64 Gb/s.

A smaller version of the DisplayPort connector is called a Mini DisplayPort. It is used in Thunderbolt 1 and Thunderbolt 2 implementations.

High Definition Multimedia Interface was developed specifically for high-definition televisions. However, its digital features also make it a good candidate for computers. There are two common types of HDMI cables. Full size HDMI Type A cable is the standard cable used to connect audio and video devices. Mini-HDMI Type C is used to connect laptops and portable devices such as tablets. The Type C connector shown in Figure 3 is smaller than the Type A connector and has 19 pins.

Thunderbolt 1 and Thunderbolt 2 use the Mini DisplayPort (MDP) adapter, while Thunderbolt 3 requires a USB-C connector.

This is a connector for analog video. It has 3 rows and 15 pins. It is also sometimes referred to as the DE-15 or HD-15 connector.

RCA connectors have a central plug with a ring around it and are used to carry audio or video. RCA connectors are often found in groups of three, where a yellow connector carries video and a pair of red and white connectors carries left and right audio channels.

BNCs connect coaxial cables to devices using a quarter-turn connection scheme. BNC is used with digital or analog audio, or video.

This connector has 6 pins and is commonly used for analog audio, video, and power in security camera applications.

Other Ports and Cables

Input/output (I/O) ports on a computer connect peripheral devices, such as printers, scanners, and portable drives. In addition to the ports and interfaces previously discussed, a computer may also have other ports:

Audio Ports – (Figure 2) Audio ports connect audio devices to the computer. Analog ports typically include a line in port to connect to an external source (e.g., stereo system), a microphone port, and line out ports to connect speakers or headphones. Digital input and output ports are also available to connect digital sources and output devices. These connectors and cables transfer pulses of light over fiber optic cables.

PS/2 Ports – (Figure 1) 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. 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.

Game port/MIDI – (Figure 2) Connects to a joystick or MIDI-interfaced device.

Ethernet Network port – (Figure 3) A network port, this used to be known as an RJ-45 port. An Ethernet network port has 8 pins and connects devices to a network. The connection speed depends on the type of network port. There a two common Ethernet standards being used. Specifically, Fast Ethernet (or 100BASE) can transmit up to 100 Mb/s, and Gigabit Ethernet (1000BASE) can transmit up to 1000 Mb/s. The maximum length of the Ethernet network cable is 100 m (328 ft.).

USB Ports and Cables - The Universal Serial Bus (USB) is a standard interface that connects peripheral devices to a computer. 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 connects multiple USB devices. A single USB port in a computer can support up to 127 separate devices with the use of multiple USB hubs. Some devices can also be powered through the USB port, eliminating the need for an external power source.

FireWire Ports and Cables - FireWire is a high-speed, hot-swappable interface that connects peripheral devices to a computer. A single FireWire port in a computer can support up to 63 devices. Some devices can also be powered through the FireWire port, eliminating the need for an external power source. FireWire uses the Institute of Electrical and Electronics Engineers (IEEE) 1394 standard and is also known as i.Link. The IEEE creates publications and standards for technology.

USB 1.1 allowed transmission rates of up to 12 Mb/s in full-speed mode and 1.5 Mb/s in low-speed mode. A USB 1.1 cable has a maximum length of 9.8 ft (3 m). USB 2.0 allows transmission speeds up to 480 Mb/s. A USB 2.0 cable has a maximum length of 16.4 ft (5 m). USB devices can only transfer data up to the maximum speed allowed by the specific port. USB 3.0 allows transmission speeds up to 5 Gb/s. USB 3.0 is backward-compatible with previous versions of USB. A USB 3.0 cable does not have a maximum defined length, although a maximum length of 9.8 ft (3 m) is generally accepted.

The IEEE 1394a standard supports data rates up to 400 Mb/s for cable lengths of 15 ft (4.5 m) or less. This standard uses a 4-pin or 6-pin connector. The IEEE 1394b (Firewire 800) standard allows for a greater range of connections, including CAT5 UTP and optical fiber. Depending on the media used, data rates are supported up to 3.2 Gb/s for distances of 328 ft (100 m) or less.

eSATA Data Cables – The eSATA cable connects SATA devices to the eSATA interface using a 7-pin data cable. This cable does not supply any power to the SATA device. A separate power cable provides power to the disk.

Note: Other ports include serial ports, parallel ports, and modem ports.

Adapters and Converters

There are many connection standards in use today. Many are interoperable but require specialized components. These components are called adapters and converters:

Adapter – This is a component that physically connects one technology to another. For example, a DVI to HDMI adapter. The adapter could be one component or a cable with different ends.

Converter – This performs the same function as an adapter but also translates the signals from one technology to the other. For example, a USB 3.0 to SATA converter enables a hard disk drive to be used as a flash drive.

DVI to HDMI adapter – The adapter is used to connect an HDMI monitor to a DVI port.

DVI to VGA adapter– (Figure 1) The adapter is used to connect a VGA cable to a DVI port.

USB A to USB B adapter – This adapter is used to connect a USB A port to a USB B port.

USB to Ethernet adapter – (Figure 2) This adapter is used to connect a USB port to an Ethernet connector.

USB to PS/2 adapter – (Figure 3) This adapter is used to connect a USB keyboard or mouse to a PS/2 port.

HDMI to VGA converter – The converter translates the VGA output signal of a PC to an HDMI output signal so that an HDMI monitor can be used.

Thunderbolt to DVI converter – The converter translates the Thunderbolt mini DisplayPort video signal to a DVI video signal so that a DVI monitor can be used.

Input Devices

Mice and Keyboards – (Figure 1) These are the two most commonly used input devices. The keyboard is used to enter text while the mouse is used to navigate the graphical user interface (GUI). Laptops also have touchpads to provide built-in mouse features.

Touch Screens – (Figure 2) These input devices have touch or pressure sensitive screens. The computer receives instructions specific to the place on the screen that the user touches.

Joysticks and Gamepads – (Figure 3) These are input devices for playing games. Gamepads allow the player to control movement and views with small sticks and multiple buttons. Many gamepads also have triggers that register the amount of pressure the player puts on them. Joysticks are often used to play flight simulation-style games.

Digital Cameras and Digital Video Cameras – (Figure 4) These input devices capture images that can be stored, displayed, printed, or altered. Stand-alone or integrated webcams capture images in real time.

Scanners – (Figure 5) These devices digitize 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.

Digitizers – (Figure 6) This device allows a designer or artist to create blueprints, images, or other artwork by using a pen-like tool called a stylus on a surface that senses where the stylus tip is touching it. Some digitizers have more than one surface, or sensor, and allow the user to create 3D models by performing actions with the stylus in mid-air.

Biometric Identification Devices – (Figure 7) These input devices identify a user based on a unique physical feature such as their fingerprints or voice. Many laptops now have fingerprint readers to automate logging in to the device.

Smart Card Readers – These input devices are typically used on a computer to authenticate the user. A smart card may be the size of a credit card with an embedded microprocessor that is typically under a gold contact pad on one side of the card.

A keyboard, video, mouse (KVM) switch is a hardware device that can be used to control more than one computer while using a single keyboard, monitor, and mouse. For businesses, KVM switches provide cost-efficient access to multiple servers. Home users can save space using a KVM switch, as seen in Figure 8, to connect multiple computers to one keyboard, monitor, and mouse.