Lecturer: Mr. Tri Djoko Wahjono, Ir, M.Sc.
By: Veronica Ong (1701317660) of class 01PCT
Task: Chapter Review of Chapter 4 from the Textbook Discovering Computers.
1.
How Are Various Styles of System Units on Desktop Computers, Notebook
Computers, and Mobile Devices Different?
The system unit is a case that contains electronic components of the computer used
to process data. System units are available in a variety of shapes and sizes.
The case of the system unit, sometimes called the chassis, is
made of metal or plastic and protects the internal electronic components from
damage. All computers and mobile devices have a system unit . On desktop
personal computers, the electronic components and most storage devices are part
of the system unit. Other devices, such as the keyboard, mouse, microphone,
monitor, printer, USB flash drive, scanner, Web cam, and speakers normally
occupy space outside the system unit. An all-in-one desktop personal computer
is an exception, which houses the monitor and the system unit in the same case.
The trend is toward a smaller form
factor, or size and shape, of
the desktop personal computer system unit. On most notebook computers,
including netbooks, the keyboard and pointing device often occupy the area on
the top of the system unit, and the display attaches to the system unit by
hinges. The location of the system unit on a Tablet PC varies, depending on the
design of the Tablet PC. With the slate Tablet PC , which typically does not
include a keyboard, the system unit is behind the display. On a convertible
Tablet PC , by contrast, the system unit is positioned below a keyboard,
providing functionality similar to a traditional notebook computer or netbook.
The difference is the display attaches to the system unit with a swivel-type
hinge, which enables a user to rotate the display and fold it down over the
keyboard to look like a slate Tablet PC. The system unit on an Ultra-Mobile PC,
a smart phone, and a PDA usually consumes the entire device. On these mobile
computers and devices, the display often is built into the system unit.
With game consoles, the input and output devices, such as controllers and a
television, reside outside the system unit. On handheld game consoles, portable
media players, and digital cameras, by contrast, the packaging around the
system unit houses the input devices and display.
2.
What Are Chips, Adapter Cards, and Other Components of the Motherboard?
The
motherboard, sometimes
called a system board,
is the main circuit board of the system unit. Many electronic components attach
to the motherboard; others are built into it. The motherboard contains many
electronic components including a processor chip, memory chips, expansion
slots, and adapter cards. Memory chips are installed on memory cards (modules)
that fit in a slot on the motherboard. A computer chip
is a small piece of semiconducting material, usually
silicon, on which integrated circuits are etched. Expansion slots hold adapter
cards that provide connections and functions not built into the motherboard. An
integrated circuit contains
many microscopic pathways capable of carrying electrical current. Each
integrated circuit can contain millions of elements such as resistors,
capacitors, and transistors. A transistor,
for example, can act as an electronic switch that opens or closes the circuit
for electrical charges. Today’s computer chips contain millions or billions of
transistors. Most chips are no bigger than one-half-inch square. Manufacturers
package chips so that the chips can be attached to a circuit board, such as a
motherboard or an adapter card.
3.
What Are the Control Unit and Arithmetic Logic Unit Components of a Processor,
and What Are the Four Steps in a Machine Cycle?
The
processor, also called the central
processing unit (CPU),
interprets and carries out the basic instructions that operate a computer. The
processor significantly impacts overall computing power and manages most of a
computer’s operations. Processors contain a control unit and an arithmetic
logic unit (ALU). These two components work together to perform processing
operations. The control unit is
the component of the processor that directs and coordinates most of the
operations in the computer. The control unit has a role much like a traffic
cop: it interprets each instruction issued by a program and then initiates the
appropriate action to carry out the instruction. Types of internal components
that the control unit directs include the arithmetic/logic unit, registers, and
buses. The arithmetic logic
unit (ALU), another
component of the processor, performs arithmetic, comparison, and other
operations. Arithmetic
operations include basic
calculations such as addition, subtraction, multiplication, and division. Comparison operations involve comparing one data item with another to
determine whether the first item is greater than, equal to, or less than the
other item. Depending on the result of the comparison, different actions may
occur.
For
every instruction, a processor repeats a set of four basic operations, which
comprise a machine cycle (Figure
4-5): (1) fetching, (2) decoding, (3) executing, and, if necessary, (4)
storing. Fetching is
the process of obtaining a program instruction or data item from memory. The
term decoding refers
to the process of translating the instruction into signals the computer can
execute. Executing is
the process of carrying out the commands. Storing,
in this context, means writing the result to memory (not to a storage medium).
4.
What Are the Characteristics of Various Personal Computer Processors, and How
Are Processors Cooled?
A
processor core, or simply core, contains the circuitry necessary to execute instructions.
The operating system views each processor core as a separate processor. A multi-core
processor is a single chip with two or more
separate processor cores. Two common multi-core processors are dual-core and
quad-core. A dual-core processor is
a chip that contains two separate processor cores. Similarly, a quad-core
processor is a chip with four separate
processor cores. The leading manufacturers of personal
computer
processor chips are Intel and AMD. These manufacturers often identify their
processor chips by a model name or model number. High-performance personal
computers today may use a processor in the Intel Core
family. Less expensive, basic personal computers may use
a brand of Intel processor in the Pentium or
Celeron family. The Xeon
and Itanium families
of processors are ideal for workstations and low-end servers. AMD is the
leading manufacturer of Intel compatible
processors, which have an internal design similar
to Intel processors, perform the same functions, and can be as powerful, but
often are less expensive.
In
the past, chip manufacturers listed a processor’s clock speed in marketing
literature and advertisements. As previously mentioned, though, clock speed is
only one factor that impacts processing speed in today’s computers. To help
consumers evaluate various processors, manufacturers such as Intel and AMD now
use a numbering scheme that more accurately reflects the processing speed of
their chips. Processor chips include technologies to improve processing
performance, for example, to improve performance of multimedia and 3-D
graphics. Most of Intel’s processor chips also include vPro
technology, which provides the capability to
track computer hardware and software, diagnose and resolve computer problems,
and secure computers from outside threats. As mentioned earlier, many personal
computer processors are multi-core, with the processor cores working
simultaneously on related instructions. These related instructions, called a
thread, can be independent or part of a larger task. Software written to
support multiple threads, called a multi-threaded
program, runs much faster than those in
non threaded environments. Processors for traditional notebook computers and
Tablet PCs also include technology to optimize and extend battery life, enhance
security, and integrate wireless capabilities. For example, Intel’s Centrino
2 mobile technology, which may have a
Pro designator depending on its capabilities, integrates wireless functionality
in notebook computers and Tablet PCs. Netbooks, smart phones, and other smaller
mobile devices often use more compact processors that consume less power, yet
offer high performance. Another type of processor, called system-on
a- chip, integrates the functions of a
processor, memory, and a video card on a single chip. Lower-priced personal
computers, Tablet PCs, networking devices, portable media players, and game
consoles sometimes have a system on- a-chip processor. The goal of system-on-a
chip manufacturers is to create processors that have faster clock speeds,
consume less power, are small, and are cost effective.
Processor
chips generate quite a bit of heat, which could cause the chip to burn up.
Although the computer’s main fan generates airflow, many of today’s personal
computer processors require additional cooling. Heat sinks/ pipes and liquid
cooling technologies often are used to help dissipate processor heat.
A
heat sink is a small
ceramic or metal component with fins on its surface that absorbs and disperses
heat produced by electrical components such as a processor (Figure 4-9). Some
heat sinks are packaged as part of a processor chip. Others are installed on
the top or the side of the chip. Because a heat sink consumes extra space, a
smaller device called a heat pipe cools
processors in notebook computers, including netbooks and Tablet PCs.
Some
computers use liquid cooling technology to reduce the temperature of a
processor. Liquid cooling technology uses
a continuous flow of fluid(s), such as water and glycol, in a process that
transfers the heated fluid away from the processor to a radiator-type grill,
which cools the liquid, and then returns the cooled fluid to the processor .
Some
mobile computers and devices often have Low Voltage or Ultra Low Voltage (ULV)
processors, which have such low power demands that they do not require
additional cooling.
5.
What Is a Bit, and How Does a Series of Bits Represent Data?
The
computer, by contrast, uses a binary system because it recognizes only two
states. The binary system is
a number system that has just two unique digits, 0 and 1, called bits. A bit
(short for binary
digit) is the smallest unit of data the
computer can process. By itself, a bit is not very informative. When 8 bits are
grouped together as a unit, they form a byte.
A byte provides enough different combinations of 0s and 1s to represent 256
individual characters. These characters include numbers, uppercase and
lowercase letters of the alphabet, punctuation marks, and others, such as the
letters of the Greek alphabet. The combinations of 0s and 1s that represent
characters are defined by patterns called a coding scheme. In one coding
scheme, the number 4 is represented as 00110100, the number 6 as 00110110, and
the capital letter E as 01000101. ASCII (pronounced
ASK-ee), which stands for American Standard Code for Information Interchange,
is the most widely used coding scheme to represent data. Coding schemes make it
possible for humans to interact with a digital computer that processes only
bits.
6.
How Do Program Instructions Transfer in and out of Memory?
When a program starts, the program’s instructions and data are
transferred to memory from storage devices. The program and operating system instructions
are in memory, and the program’s window appears on the screen. When you quit the
program, the program instructions are removed from memory, and the program no
longer is displayed on the screen.
7.
What Are the Various Types of Memory?
The
system unit contains two types of memory: volatile and nonvolatile. When the
computer’s power is turned off, volatile memory loses
its contents. Nonvolatile memory,
by contrast, does not lose its contents when power is removed from the
computer. Thus, volatile memory is temporary and nonvolatile memory is
permanent. RAM is the most common type of volatile memory. Examples of
nonvolatile memory include ROM, flash memory, and CMOS.
RAM
(random access
memory), also called main
memory, consists of memory chips that can
be read from and written to by the processor and other devices. When you turn
on power to a computer, certain operating system files (such as the files that
determine how the desktop appears) load into RAM from a storage device such as
a hard disk. These files remain in RAM as long as the computer has continuous
power. As additional programs and data are requested, they also load into RAM
from storage.
Most
of today’s computers improve their processing times with cache
(pronounced cash). Two types of cache are memory cache
and disk cache. Memory cache helps
speed the processes of the computer because it stores frequently used
instructions and data. Most personal computers today have two types of memory
cache: L1 cache and L2 cache. Some also have L3 cache.
Read-only
memory (ROM pronounced
rahm) refers to memory chips storing permanent data and instructions. The data
on most ROM chips cannot be modified — hence, the name read-only. ROM is
nonvolatile, which means its contents are not lost when power is removed from
the computer. In addition to computers, many devices contain ROM chips. For
example, ROM chips in printers contain data for fonts.
Flash
memory is a type of nonvolatile memory
that can be erased electronically and rewritten, similar to EEPROM. Most
computers use flash memory to hold their startup instructions because it allows
the computer easily to update its contents.
Some
RAM chips, flash memory chips, and other memory chips use complementary
metal-oxide semiconductor (CMOS
pronounced SEE-moss) technology because it provides high
speeds and consumes little power. CMOS technology uses battery power to retain
information even when the power to the computer is off. Battery-backed CMOS
memory chips, for example, can keep the calendar, date, and time current even
when the computer is off. The flash memory chips that store a computer’s
startup information often use CMOS technology.
Access
time is the amount of time it takes the
processor to read data, instructions, and information from memory. A computer’s
access time directly affects how fast the computer processes data. Accessing
data in memory can be more than 200,000 times faster than accessing data on a
hard disk because of the mechanical motion of the hard disk.
8.
What Are the Purpose and Types of Expansion Slots and Adapter Cards, and What
Are the Different Slots for Flash Memory Devices?
An
expansion slot is a socket
on the motherboard that can hold an adapter card. An adapter
card, sometimes called an expansion
card, is a circuit board that enhances
functions of a component of the system unit and/or provides a connection to a peripheral.
A sound card enhances
the sound-generating capabilities of a personal computer. A video
card, also called a graphics
card, converts computer output into a
video signal that displays an image on the screen. A memory
card is a removable fl ash memory device
that you insert and remove from a slot in a personal computer, a game console,
a mobile device, or card reader/writer. A USB flash
drive plugs in a USB port on a computer
or mobile device. A PC Card slot or
an ExpressCard slot holds
a PC Card or ExpressCard
module.
9.
What Is the Difference between a Port and a Connector, and What Are the
Differences among the Various Types of Ports?
A
port is the point at
which a peripheral attaches to or communicates with a system unit so that the
peripheral can send data to or receive information from the computer. An
external device, such as a keyboard, monitor, printer, mouse, and microphone,
often attaches by a cable to a port on the system unit. Instead of port, the
term jack sometimes
is used to identify audio and video ports. The front and back of a system unit
on a desktop personal computer contain many ports.
A
connector joins a
cable to a port. A connector at one end of a cable attaches to a port on the
system unit, and a connector at the other end of the cable attaches to a port
on the peripheral. Most connectors and ports are available in one of two
genders: male or female. Male connectors and ports have one or more exposed
pins, like the end of an electrical cord you plug in the wall. Female
connectors and ports have matching holes to accept the pins on a male connector
or port, like an electrical wall outlet.
A
USB port, short for universal
serial bus port, can connect up to 127
different peripherals together with a single con nector. A FireWire
port can connect multiple types of
devices that require faster data transmission speeds. Bluetooth
technology uses radio waves to transfer data between two
devices. A SCSI port attaches
the system unit to SCSI peripherals, such as disk drives and printers. An eSATA
port connects an external SATA hard disk
to a computer. An IrDA port allows
wireless devices to transmit signals to a computer via infrared light waves. A serial
port transmits data one bit at a time. A
MIDI port connects
the system unit to a musical instrument.
10.
What Are the Types of Buses in a Computer?
Buses
are used to transfer bits from input devices to memory, from memory to the
processor, from the processor to memory, and from memory to output or storage
devices. Buses consist of two parts: a data bus and an address bus. The data
bus is used to transfer actual data and
the address bus is
used to transfer information about where the data should reside in
memory.
A computer has these basic types of buses: a system bus, possibly a backside
bus, and an expansion bus. A system bus,
also called the front side bus ( FSB), is
part of the motherboard and connects the processor to main memory. A backside
bus ( BSB) connects the processor to cache. An
expansion bus allows the
processor to communicate with peripherals. When computer professionals use the
term bus by itself, they usually are referring to the system bus.
The
types of expansion buses : PCI bus, PCI Express bus, AGP bus, USB, FireWire
bus, and PC Card bus.
The
PCI bus (Peripheral
Component Interconnect bus) is a high-speed expansion bus that connects higher
speed devices. Types of cards you can insert in a PCI bus expansion slot
include video cards, sound cards, SCSI cards, and high-speed network cards.
The
PCI Express (PCIe)
bus is an expansion
bus that expands on and doubles the speed of the original PCI bus. Nearly all
video cards today use the PCI Express bus, as well as many hard disks and
network cards. The ExpressCard technology used in traditional notebook
computers and Tablet PCs also works with the PCI Express bus. Experts predict
the PCI Express bus eventually will replace the PCI bus completely.
The
Accelerated Graphics Port (AGP)
is a bus designed by Intel to improve the speed with which 3-D graphics and
video transmit. With an AGP video card in an AGP bus slot, the AGP bus provides
a faster, dedicated interface between the video card and memory. Newer
processors support AGP technology.
The
USB (universal serial bus) and FireWire bus are
buses that eliminate the need to install cards in expansion slots. In a
computer with a USB, for example, USB devices connect to each other outside the
system unit, and then a single cable attaches to the USB port. The USB port
then connects to the USB, which connects to the PCI bus on the motherboard. The
FireWire bus works in a similar fashion. With these buses, expansion slots are
available for devices not compatible with USB or FireWire.
•The
expansion bus for a PC Card is the PC Card
bus. With a PC Card inserted in a PC
Card slot, data travels on the PC Card bus to the PCI bus.
11.
What Is the Purpose of a Power Supply, and How Does It Keep Cool?
The
power supply is the
component of the system unit that converts the wall outlet AC power into DC
power. Different motherboards and computers require
different wattages on the power supply. Notebook computers, including netbooks
and Tablet PCs, can run using either batteries or a power supply. If a power
supply is not providing the necessary power, the computer will not function
properly. Built into the power supply is a fan that keeps the power supply
cool. Some have variable speed fans that change speed or stop running,
depending on temperature in the system unit. Many newer computers have
additional fans near certain components in the system unit such as the
processor, hard disk, and ports. Some users install more fans to help dissipate
heat generated by the components of the system unit. Mobile users may place
their notebook computer on a cooling pad to help disperse the computer’s heat.
12.
How Do You Clean a System Unit on a Personal Computer or Mobile Device?
Before
cleaning the exterior of a computer or mobile device, turn it off, and if
necessary, unplug it from the electrical outlet, remove the battery, and
disconnect all cables from the ports. Use compressed air to blow away dirt from
any openings on the case, such as drives, slots, ports, and fan vents. Use an
antistatic wipe to clean the exterior of the case and a cleaning solution on a
soft cloth to clean the screen. While working inside the case, be sure to wear
an antistatic wristband. If you do not feel comfortable cleaning the inside of
the case, you can have a professional or computer company clean it for you. Use
a vacuum and compressed air to remove dust inside the case.
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