BUS LINES
As mentioned earlier, a bus line-also known simply as a bus-connects th s Parts of the CPU to each other: Buses also link the CPU to various other components on the system board. A bus is a pathway for b representing data and instructions. The number of bits that can travel simultaneously down a bus is known a the bus width.
A bus is similar to a multilane highway that moves bits rather than cars from one location to another. The number of traffic lanes determines the bus width. A highway (bus line) with more traffic lanes (bus width) can move traffic (data and instructions) more efficiently. For example, a 64. bit bus can move twice as much information at a time as a 32-bit bus, Why should you even care about what a bus line is? Because as microprocessor chips have changed, so have bus lines. Bus design or bus architecture is an important factor relating to the speed and power for a particular computer. Additionally, many devices, such as expansion cards, will work with only one type of bus.
Every computer system has two basic categories of buses. One category, called system buses, connects the CPU to memory on the system board. The other category, called expansion buses, connects the CPU to other components on the system board, including expansion slots.
EXPANSION BUSES
Computer systems typically have a combination of different types of expansion buses. The principal types are USB, FireWire, and PCie.
● Universal serial bus (USB) is widely used today. External USB devices are connected from one to another or to a common point or hub and then onto the USB bus. The USB bus then connects to the PCI bus on the system board. The current USB standard is USB 3,1.
● FireWire buses are similar to USB buses but more specialized. They are used primarily to connect audio and video equipment to the system board.
● PCI Express (PCIe) is widely used in many of today's most powerful computers. Unlike most other buses that share a single bus line or path with several devices, the PCie bus provides a single dedicated path for each connected device.
What is a bus, and what is bus width?
What is the difference between a system and an expansion bus?
Discuss three types of expansion buses.
PORTS
A port is a socket for external devices to connect to the system unit. Some ports connect directly to the system board, while others t to cards that are inserted into slots on the system board. Some ports standard features of most computer systems, and others are more specialized.
STANDARD PORTS
Most desktop and laptop computers come with a standard set of ports for connecting a monitor, keyboard, and other peripheral devices. The most common ports follow,
● Universal serial bus (USB) ports can be used to connect several devices to the system unit and are widely used to connect keyboards, mice, printers, storage devices, and a variety of specialty devices. One such device, a USB TV tuner card, allows users to view and record television programs. To learn how you can use a TV tuner card. A single USB port can be used to connect many USB devices to the system unit.
● High Definition Multimedia Interface (HDMI) ports provide high-definition video and audio, making it possible to use a computer as a video jukebox or an HD video recorder.
● Thunderbolt ports, first introduced in Apple's MacBook Pro computer provide high-speed connections. A single port can connect up to seven separate devices connected one to another. Thunderbolt ports promise to replace a number of different types of ports including Mini Display Port.
● Ethernet ports are a high-speed networking port that has become a standard for many of today's computers, Ethernet allows you to connect multiple computers for sharing files, or to a DSL or cable modem for high-speed Internet access.
SPECIALIZED PORTS
In addition to standard ports, there are numerous specialty ports. The most common include:
● External serial advanced technology attachment (eSATA) ports provide high-speed connections for external hard disk drives, optical discs, and other large secondary storage devices.
● Musical instrument digital interface (MIDI) ports are a special type of porn for connecting musical instruments like an electronic keyboard to a sound card. The sound card converts the music into a series of digital instructions. These instructions can be processed immediately to reproduce the music or saved to a file for later processing.
● Mini DisplayPort (Mini DP or mDP) ports are audiovisual ports typically used to connect large monitors. These ports are used with many Apple Macintosh computers.
● VGA (Video Graphics Adapter) and DVI (Digital Video Interface) ports provide connections to analog and digital monitors, respectively. DVI has become the most commonly used standard, but VGA ports are still provided on almost all systems for compatibility with older/lower-cost monitors.
● FireWire ports provide high-speed connections to specialized FireWire devices such as camcorders and storage devices.
CABLES
Cables are used to connect exterior devices to the system unit via the ports. One end of the cable is attached to the device, and the other end has a connector that is attached to a matching connector on the port.
POWER SUPPLY
Computers require direct current (DC) to power their electronic components and to represent data and instructions. DC power can be provided indirectly by converting alternating current (AC) from standard wall outlets or directly from batteries.
● Desktop computers have a power supply unit located within the system unit.This unit plugs into a standard wall outlet, converts AC to DC, and provides the power to drive all of the system unit components.
● Laptops typically use AC adapters that are located outside the system unit. AC adapters plug into a standard wall outlet convert AC to DC, provide power to drive the system unit components, and can recharge the batteries. These computers can be operated either using an AC adapter plugged into a wall outlet or using battery power. Their batteries typically provide sufficient power for up to eight hours before they need to be recharged.
● Most tablets and mobile devices use internal AC adapters that use a cable to connect to a standard wall outlet. Some smartphones, however, use a wireless charging platform eliminating the cable.Unlike most laptops, most tablets, mobile devices, and wearable computers can operate only using battery power. Their AC adapters or charging platforms are only used to recharge batteries.
What are ports?
What do they do?
Describe four standard ports and five specialized ports.
What is a power supply unit?
What is an AC adapter?
What is a charging platform?
ELECTRONIC DATA AND INSTRUCTIONS
Have you ever wondered why it is said that we live in a digital world? Ir's Because computers cannot recognize information the same way you and I can. People follow instructions and process data using letters, numbers, and special characters. For example, if we wanted someone to add the numbers 3 and 5 together and record the answer, we might say "please add 3 and 5." The system unit, however, is electronic circuitry and cannot directly process such a request.
Our voices create analog, or continuous, signals that vary to represent different tones, pitch, and volume. Computers, however, can recognize only digital electronic signals. Before any processing can occur within the system unit, a conversion must occur from what we understand to what the system unit can electronically process.
NUMERIC REPRESENTATION
What is the most fundamental statement you can make about electricity? It is simply this: It can be either on or off. Indeed, there are many forms of technology that can make use of this two-state on/off, yes/no, present/absent arrangement For instance, a light switch may be on or off, or an electric circuit open or closed. A specific location on a tape or disk may have a positive charge or a negative charge. This is the reason, then, that a two-state or binary system is used to represent data and instructions.
The decimal system that we are all familiar with has 10 digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). The binary system, however, consists of only two digits and 1. Each 0 or 1 is called a bit-short for binary digit. In the system unit, the 1 can be represented by a negative charge and the 0 by no electric charge. In order to represent numbers, letters, and special characters, bits are combined into groups of eight called bytes. Whenever you enter a number into a computer system, that number must be converted into a binary number before it can be processed. Any number can be expressed as a binary number. Binary numbers, however are difficult for humans to work with because they require so many digits. Instead, binary numbers are often represented in a format more readable by humans. The hexadecimal system, or hex, uses 16 digits ( 0123456789 A, B, C, D. E, F ) to represent binary numbers. Each hex digit represents four binary digits. and two hex digits are commonly used together to represent 1 byte (8 binary digits). You may have already seen hex when selecting a colour in a website design or drawing application, or when entering the password for access to a wireless network.
CHARACTER ENCODING
As we've seen computers must represent all numbers with the binary system internally, What about text? How can a computer provide representations of the non-numeric characters we use to communicate, such as the sentence you are reading now? The answer is character encoding schemes or standards.
Character encoding standards assign a unique sequence of bits to each character. Historically, personal computers used the ASCII (American Standard Code for Information Interchange) to represent characters, while mainframe computers used EBCDIC (Extended Binary Coded Decimal Interchange Code). These schemes were quite effective; however, they are limited. ASCII, for example, only uses 7 bits to represent each character, which means that only 128 total characters could be represented. This was fine for most characters in the English language but was not large enough to support other languages such as Chinese and Japanese. These languages have too many characters to be represented by the 7-bit ASCII code.
The explosion of the Internet and subsequent globalization of computing have led to a new character encoding called Unicode, which uses 16 bits. The Unicode standard is the most widely used character encoding standard and is recognized by virtually every computer system. The first 128 characters are assigned the same sequence of bits as ASCII to maintain compatibility with older ASCII-formatted information. However, Unicode uses a variable number of bits to represent each character, which allows non-English characters and special characters to be represented. These codes, also called as Binary codes.
