The System Unit

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24 terms · Concept questions and answers.

What is the system unit?

The system unit, also known as the system chassis, is a container that houses most of the electronic components that make up a computer system.

Describe and compare the four basic types of microcomputer system units.

Desktops this is the most powerful type of microcomputer. Most desktops have their system unit in a separate case. This case contains the system's electronic components and selected secondary storage devices. Input and output devices, such as a mouse, keyboard, and monitor, are located outside the system unit. This type of system unit is designed to be placed either horizontally or vertically.
Notebooks although typically not as powerful as desktops, notebooks are portable and much smaller. Their system units are housed with selected secondary storage devices and input devices (keyboard and pointing device). Located outside the system unit, the monitor is attached by hinges. Notebooks are often called laptops.
Tablets, also known as tablet computers, are the newest and one of the most popular types of computer. They are effectively a thin slab that is all monitor with the system unit located behind the monitor. Tablets are smaller, lighter, and generally less powerful than notebooks. Like a notebook, tablets have a flat screen but typically do not have a standard keyboard. Instead, tablets typically use a virtual keyboard that appears on the screen and is touch- sensitive. One distinguishing feature among tablet computers is the operating system that controls their operations. For example, Apple's iPad uses the mobile operating system iOS. It is capable of running apps specifically designed for it. Many other tablets use Microsoft's Windows 8 operating system and can run many general- purpose applications as well as apps specifically designed for it.
Handheld computers are the smallest and are designed to fit into the palm of one hand. These systems contain an entire computer system, including the electronic components, secondary storage, and input and output devices. By far the most popular handheld computer is the smartphone. These devices are smaller and generally less powerful than tablets. Smartphones greatly extend the capabilities of a cell phone by providing computing power. In addition to capturing and sending audio and video, smartphones run apps, connect to the Internet, and more. Their system unit is located behind the display screen and keypad

What are tower units? What is an all- in- one? What is a netbook?

Tower units or tower computers are desktop system units that are placed vertically
An all- in- one are some desktop computers, like Apple's iMac, have their monitor and system unit housed together in the same case.
Netbooks are a type of notebook. They are smaller, less powerful, and less expensive than other notebooks. Netbooks are designed to support on- the go web browsing and e- mail access. They reduce space and weight by leaving out components such as optical drives

What is the system board, and what does it do?

The system board is also known as the mainboard or motherboard.
The system board controls communications for the entire computer system. Every component within the system unit connects to the system board. All external devices including the keyboard, mouse and monitor connect to the system board. It acts as a data path and traffic monitor, allowing the various components to communicate efficiently with one another. On a desktop computer, the system board is typically located at the bottom of the system unit or along one side. It is a large flat circuit board covered with a variety of different electronic components including sockets, slots, and bus lines.

Define and describe sockets, slots, and bus lines.

•Sockets provide a connection point for small specialized electronic parts called chips.
• Slots provide a connection point for specialized cards or circuit boards. These cards provide expansion capability for a computer system. For example, a wireless networking card plugs into a slot on the system board to provide a connection to a local area network.
• Connecting lines called bus lines provide pathways that support communication among the various electronic components that are either located on the system board or attached to the system board.

What are chips? How are chips attached to the system board?

Chips consist of tiny circuit boards etched onto squares of sandlike material called silicon. These circuit boards can be smaller than the tip of your finger. A chip is also called a silicon chip, semiconductor, or integrated circuit. Chips are mounted on carrier packages. These packages plug either directly into sockets on the system board or onto cards that are then plugged into slots on the system board. Sockets are used to connect the system board to a variety of different types of chips, including microprocessor and memory chips.

Name and describe the two components of a microprocessor.

• Control unit: The control unit tells the rest of the computer system how to carry out a program's instructions. It directs the movement of electronic signals between memory, which temporarily holds data, instructions, and processed information, and the arithmetic- logic unit. It also directs these control signals between the CPU and input and output devices.
• Arithmetic- logic unit: The arithmetic- logic unit , usually called the ALU , performs two types of operations: arithmetic and logical. Arithmetic opera-tions are the fundamental math operations: addition, subtraction, multiplica-tion, and division. Logical operations consist of comparisons such as whether one item is equal to ( 5 ), less than (,), or greater than (.) the other.

Define word, clock speed, multicore chip, and parallel processing.

A word is the number of bits ( such as 16, 32, or 64) that can be accessed at one time by the CPU. The more bits in a word, the more data a computer can process at one time. Eight bits group together to form a byte. A 32- bit-word computer can access 4 bytes at a time. A 64- bit- word computer can access 8 bytes at a time. Therefore, the computer designed to process 64- bit words has greater processing capacity. Other factors affect a computer's processing capability including how fast it can process data and instructions.
Clock speed which is related to the number of times the CPU can fetch and process data or instructions in a second, and represents the processing speed of a microprocessor. Older microcomputers typically process data and instructions in millionths of a second, or microseconds. Newer microcomputers are much faster and process data and instructions in billionths of a second, or nanoseconds. Supercomputers, by contrast, operate at speeds measured in picoseconds— 1,000 times as fast as microcomputers. Logically, the higher a microprocessors clock speed, the faster the microprocessor. However, some processors can handle multiple instructions per cycle or tick of the clock; this means that clock speed comparisons can only be made between processors that work the same way.
The multicore chip a traditional microcomputer's CPU is typically contained on a single microprocessor chip. A new type of chip, the multicore chip, can provide two or more separate and independent CPUs. For example, a quad- core processor could have one core computing a complex Excel spreadsheet, a second core creating a report using Word, a third core locating a record using Access, and a fourth core running a multimedia presentation. More significantly, however, is the potential for micro-computers to run very large, complex programs that previously required expensive and specialized hardware.
Parallel processing allows computers to understand how to divide tasks into parts that can be distributed across each core. Operating systems such as Windows 8 and Mac OS X support parallel processing. Software developers use this technology for a wide range of applications from scientific programs to sophisticated computer games.

What are specialty processors? Describe coprocessors.

Specialty processors
In addition to microprocessor chips, a variety of more specialized processing chips have been developed.
• Coprocessors are specialty chips designed to improve specific computing operations. One of the most widely used is the graphics coprocessor, also called a GPU (graphics processing unit). These processors are designed to handle a variety of specialized tasks such as displaying 3- D images and encrypting data.
• Many cars have more than 70 separate specialty processors to control nearly everything from fuel efficiency to satellite entertainment and tracking systems.

What is memory? Name and describe three types.

Memory is a holding area for data, instructions, and information.
Random- Access Memory (RAM) chips hold the program (sequence of instructions) and data that the CPU is presently processing. RAM is called temporary or volatile storage because everything in most types of RAM is lost as soon as the microcomputer is turned off.
Read-Only Memory (ROM) chips have information stored in them by the manufacturer. Unlike RAM chips, ROM chips are not volatile and cannot be changed by the user. "Read only" means that the CPU can read, or retrieve, data and programs written on the ROM chip. However, the computer cannot write- encode or change- the information or instructions in ROM. Not long ago, ROM chips were typically used to contain almost all the instructions for basic computer operations. For example, ROM instructions are needed to start a computer, to access memory, and to handle keyboard input. Recently, however, flash memory chips have replaced ROM chips for many applications.
Flash memory offers a combination of the features of RAM and ROM. Like RAM, it can be updated to store new information. Like ROM, it does not lose that information when power to the computer system is turned off. Flash memory is used for a wide range of applications. For example, it is used to store the start- up instructions for a computer.

What are cache memory, DIMM, and virtual memory?

Cache memory (pronounced "cash") improves processing by acting as a temporary high- speed holding area between the memory and the CPU. The computer detects which information in RAM is most frequently used and then copies that information into the cache. When needed, the CPU can quickly access the information from the cache.
DIMM (dual in- line memory module) is an expansion module like an additional RAM can be added to a computer system by inserting it into the system board.
Virtual memory most of today's operating systems support virtual memory. With virtual memory, large programs are divided into parts and the parts are stored on a secondary device, usually a hard disk. Each part is then read into RAM only when needed. In this way, computer systems are able to run very large programs.

Define ROM and flash memory.

Read-Only Memory (ROM) chips have information stored in them by the manufacturer. ROM chips are not volatile and cannot be changed by the user.
Flash memory offers a combination of the features of RAM and ROM. Like RAM, it can be updated to store new information. Like ROM, it does not lose that information when power to the computer system is turned off.

What are expansion slots and cards? Name four expansion cards.?

Expansion slots located on the system board and it allow users to expand their systems.
Expansion cards optional devices insert into these slots.
Ports on the cards allow cables to be connected from the expansion cards to devices outside the system unit.
There are a wide range of different types of expansion cards.
Some of the most commonly used expansion cards are
• Graphics cards provide high- quality 3- D graphics and animation for games and simulations.
• Sound cards accept audio input from a microphone and convert it into a form that can be processed by the computer. Also, these cards convert internal electronic signals to audio signals so they can be heard from external speakers or home theater systems.
• Network interface cards (NIC), also known as network adapter cards, are used to connect a computer to a network. The network allows connected computers to share data, programs, and hardware. The network adapter card typically connects the system unit to a cable that connects to the network.
• Wireless network cards allow computers to be connected without cables. Wireless networks in the home are widely used to share a common Internet connection. Each device on the network is equipped with a wireless network card that communicates with the other devices.

Discuss Plug and Play.

Plug and Play was originally a set of specific hard-ware and software standards developed by Intel, Microsoft, and others. As hardware and software have evolved, however, Plug and Play has become a generic term that is associated with the ability to plug any device such as a printer or monitor into a computer and have it play or work immediately. Some devices, however, are not Plug and Play and require that new device drivers be installed. These cards plug into PCMCIA slots (called PC card slots) or, most recently, Express Card slots.

What are PC cards, PCMCIA slots, and ExpressCard slots?

PC are sized expansion cards have been developed to meet the size constraints of notebook, tablet, and handheld computers, small credit card.
PCMCIA slots (called PC card slots) PC cards plug into PCMCIA.
Express Card slots is the recently used slots for PC card.

Hat is a bus, and what is bus width?

Bus — also known as a bus line — connects the 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 bits representing data and instructions.
The bus width is the number of bits that can travel simultaneously down a bus.

What is the difference between a system and an expansion bus?

System buses connect the CPU to memory on the system board.
Expansion buses connect the CPU to other components on the system board, including expansion slots.

Discuss three types of expansion buses?

•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 3.0.
•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 are ports? What do they do?

A port is a socket for external devices to connect to the system unit.
Some ports connect directly to the system board, while others connect to cards that are inserted into slots on the system board.

Describe four standard ports and five specialized ports.

Standard Ports most desktop and notebook microcomputers come with a standard set of ports for connecting a monitor, keyboard, and other peripheral devices.
The most common ports include
• 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.
• 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.
• FireWire ports provide high- speed connections to specialized FireWire devices such as camcorders and storage devices.
• 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 including eSATA, HDMI, MIDI, MiniDP, and S/ PDIF.
• External Serial Advanced Technology Attachment (eSATA) ports provide very- high- speed connections for external hard disk drives, optical discs, and other large secondary storage devices.
• 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.
• Mini Display Port (MiniDP or mDP) ports are an audiovisual port typically used to connect large monitors. These ports are used with many Apple Macintosh computers. • Musical instrument digital interface (MIDI) ports are a special type of port 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.
• Sony/ Philips Digital Interconnect Format (S/ PDIF) ports are also known as optical audio connections. These ports are used to integrate computers into high- end audio and home theater systems.

What is a power supply unit? What is an AC adapter?

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. Used in the desktop computers
AC adapters are typically located outside the system unit. Plug into a standard wall outlet, convert AC to DC, provide power to drive the system unit components, and can recharge the batteries. AC adapters used in notebooks and tablets.
Notebooks and tablets can be operated either using an AC adapter plugged into a wall outlet or using battery power. Their batteries typically provide sufficient power for 9 to 10 hours before they need to be recharged.

What is the difference between an analog and a digital electronic signal?

Human voices create analog (continuous) signals. Computers only recognize 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.

What are decimal and binary systems? How are they different?

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 consists of only two digits— 0 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 positive 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.

Compare EBCDIC, ASCII, and Unicode.

ASCII (American Standard Code for Information Interchange) used be the microcomputers to represent characters.
EBCDIC (Extended Binary Coded Decimal Interchange Code) used by mainframe computers
ASCII 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.
Unicode uses a variable number of bits to represent each character, which allows non- English characters and special characters to be represented.

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