csc1100 - chapter02 - components of the system unit
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Chapter 2The Components of the
System Unit
Chapter Objectives
Identify chips, adapter cards, and other components in system unit
Identify chips, adapter cards, and other components in system unit
Describe the components of a processorand how they complete a machine cycle
Describe the components of a processorand how they complete a machine cycle
Identify characteristics of various personal Identify characteristics of various personal
Describe the types of expansion slotsand adapter cards
Describe the types of expansion slotsand adapter cards
Explain the differences among a serial port, a parallel port, a USB port, a FireWire port, and other ports
Explain the differences among a serial port, a parallel port, a USB port, a FireWire port, and other portsIdentify characteristics of various personal
computer processors on the market todayIdentify characteristics of various personal computer processors on the market today
Define a bit and describe how a series of bitsrepresents data
Define a bit and describe how a series of bitsrepresents data
Differentiate among the varioustypes of memory
Differentiate among the varioustypes of memory
Describe how busescontribute to acomputer’s processing speed
Describe how busescontribute to acomputer’s processing speed
Identify components in mobile computersand mobile devices
Identify components in mobile computersand mobile devices
The System Unit
What is the system unit?� Case that contains
electronic components of the computer used to process data� Also known as � Also known as
chassis
Learning Outcome
Successful students will be able to:
Describe the characteristics of computer hardware devices and explain their functionalities.
The System Unit
What are common components inside the system unit?
� Memory� Adapter cards
� Sound card
power supply drive bays
processor
� Processor
� Sound card� Video card
� Ports� Drive bays� Power supply
ports memory
sound cardvideo card
The System Unit
What is the motherboard?� Main circuit
board in system unit
� Contains adapter cards, processor cards, processor chips, andmemory chips
� Also calledsystem board
The System Unit
What is a chip?� Small piece of semi-conducting material on which
integrated circuits are etched� Integrated circuits contain many microscopic pathways
capable of carrying electrical current – can contain millions of elements: resistors, capacitors, transistors,…
p. 186
millions of elements: resistors, capacitors, transistors,…
� Chips are packaged so they can be attached to a circuit board
ProcessorProcessor
Control Control UnitUnit
Arithmetic Arithmetic Logic Unit (ALU)Logic Unit (ALU)
Arithmetic Arithmetic Logic Unit (ALU)Logic Unit (ALU)
Processor
What is the central processing unit (CPU)?
� Interprets and carries out basic instructions that operate a computer
InstructionsInstructionsDataData
InformationInformation
Control Control UnitUnit
� Control unit directs and coordinates operations in computer
p. 187 Fig. 4-4
InputInputDevicesDevices
StorageStorageDevicesDevices
OutputOutputDevicesDevicesMemoryMemoryDataData InformationInformation
InstructionsInstructionsDataData
InformationInformation
InformationInformationcomputer
� Arithmetic logic unit (ALU) performs arithmetic, comparison, and logical operations
� Also called theprocessor
Processor
What is a machine cycle?
Step 1. FetchObtain program instruction or data item from memory
� Four operations of the CPU comprise a machine cycle
Processor
Control Unit
Memory
ALU
Step 2. DecodeTranslate instruction into commands
Step 4. StoreWrite result to memory
Step 3. ExecuteCarry out command
Processor
What is pipelining?� CPU begins fetching second instruction before
completing machine cycle for first instruction� Results in faster processing
Stores location Stores location from where instruction from where instruction
Processor
What is a register?� Temporary high-speed storage area that holds
data and instructions
from where instruction from where instruction was fetchedwas fetched
Stores Stores instruction while it is instruction while it is
being decodedbeing decoded
Stores data Stores data while ALU while ALU computes itcomputes it
Stores results Stores results of calculationof calculation
Processor
What is the system clock?� Controls timing of all computer operations� Generates regular electronic pulses, or ticks, that set
operating pace of components of system unit
Each tick Each tick is a is a
clock cycleclock cycle
Pace of system Pace of system clock is clock is clock speedclock speed
Most clock speeds are Most clock speeds are in the gigahertz (GHz) in the gigahertz (GHz)
range (1 GHz = one range (1 GHz = one billion ticks of system billion ticks of system
clock per second)clock per second)
Processor speed can Processor speed can also be measured in also be measured in
mmillions of illions of iinstructions nstructions pper er ssecond econd (MIPS)(MIPS)
Processor
Comparison of some of the more widely used processors
Quick Quiz
1) What is the system unit?Answer: A case that contains electronic components of the computer used to process data
Answer: Many microscopic pathways capable of carrying electrical
2) What does an integrated circuit contain?
Many microscopic pathways capable of carrying electrical current
Answer: The control unit is the component of the processor that directs and coordinates most computer operations; the arithmetic logic unit is the component that performs arithmetic and comparison operations.
3) How is the control unit different from the arithmetic logic unit?
Processor
What are heat sinks, heat pipes, and liquid cooling?
� Heat sink —small ceramic or metal component with fins – absorbs & disperses heat produced by electrical components
� Heat pipe —smaller
Besides computer’s main fan, today’s processors require additional cooling
� Heat pipe e—smaller device for notebook computers
� Liquid cooling —uses a continuous flow of fluids (water, glycol,..) to transfer heat away from processor to a radiator type grill and returns the cooled fluid to the processor
Processor
� Mobile computers & devices often have Low Voltage or Ultra Low Voltage (UVL) processors� Have such low power demands that they do not
require additional cooling.
Processor
What is parallel processing?
Control ProcessorControl Processor
Processor 1Processor 1 Processor 2Processor 2 Processor 3Processor 3 Processor 4Processor 4
� Using multiple processors simultaneouslyto execute a program faster MemoryMemory MemoryMemory MemoryMemory MemoryMemoryfaster
� Requires special software to divide problem and bring results together
Parallel Processing
� Single problem divided into portions
� Multiple processors work on their assigned portions of the problem at the same time
� Some PC use dual-core or multi-core processors
� Others have two or more separate processors � Others have two or more separate processors chips.
� Massively parallel processing� large scale parallel processing � involves hundreds or thousands of processors.� Used by supercomputers – AI & weather forecasting
applications.
Data Representation
How do computers represent data?
� Recognize only two discrete states: on or off
� Use a binary systemto
� Most computers aredigital
� Use a binary systemto recognize two states
� Use Number system with two unique digits: 0 and 1, called bits (short for binary digits)
Data Representation
� Computers – electronic devices powered by electricity – has only two states: ON and OFF
� The digit 0 represents the electronic state OFF:� absence of electronic charge
� The digit 1 represents the electronic state ON: presence of electronic charge
The digit 1 represents the electronic state ON: � presence of electronic charge
� The binary system is a number system that has just two unique digits, 0 and 1, called bit.
� A bit (is not very informative) is the smallest unit of data the computer can process.
Data Representation
What is a byte?� EIGHT bits grouped together as a unit� Provides enough different combinations of 0s and 1s
to represent 256 individual characters� Numbers
� Uppercase � Uppercase and lowercase letters
� Punctuation marks
� Other
Data Representation
What are three popular coding systems to represent data?
� ASCII - American Standard Code for Information Interchange- Used in PCs & servers
� EBCDIC - Extended Binary Coded Decimal Interchange Code- Used primarily on mainframe & supercomputers
(both coding schemes sufficient for English & Western Europe languages but not for Asian, using different alphabets)
� Unicode - 16-bit coding scheme capable of representing allworld’s languages
- implemented in Windows Vista, XP, Mac OS & Linux
ASCII Symbol EBCDIC
00110000 0 11110000
00110001 1 11110001
00110010 2 11110010
00110011 3 11110011
Data Representation
How is a letter converted to binary form and back?
Step 1.The user presses the capital letter D(shift+D key) on the keyboard.
Step 2.An electronic signal for the capital letter D is sent to the system unit.
Step 3.The signal for the capital letter D is converted to its ASCII binary code(01000100) and is stored in memory for processing.
Step 4.After processing, the binary code for the capital letter D is converted to an image, and displayed on the output device.
Quick Quiz
1) What is a dual-core processor? Answer: A single chip that contains two separate processors
2) How are analog signals different from digital signals? Answer: Analog uses continuous (wave form) signals that vary in strength and quality; digital signals, which are used by most computers, recognize only two discrete states: on and off
signals?
Memory
What is memory?� Electronic components that store:
- instructions waiting to be executed,
- data needed by those instructions, and
- the resultsof processed data (information)
� Consists of one or more chips on motherboard or other circuit board
� Each bytestored in memory at unique locationcalled an address
Memory
What is memory? (cont.)
� A byte (a character)– 8 bits - is the basic storage unit in memory
� Each byteresides temporarily in a location in memorythat has an address– a unique number that identifies the location of a byte in memorylocation of a byte in memory
� To access data or instruction in memory, computer references the addresses that contain bytes of data
Memory
How is memory measured?
Term Abbreviation Approximate Size
Kilobyte KB or K 1 thousand bytes
� By number of bytesavailable for storage
Kilobyte KB or K 1 thousand bytes
Megabyte MB 1 million bytes
Gigabyte GB 1 billion bytes
Terabyte TB 1 trillion bytes
� Actually a kilobyte = 1,024 bytes
Memory
What is random access memory (RAM)?
Also called Also called Most RAM is Most RAM is
Memory chips that can be Memory chips that can be read from and written read from and written
to by processor & other devicesto by processor & other devices
The more RAM a The more RAM a computer has, the computer has, the faster it respondsfaster it responds
Also called Also called main memory main memory
or primary or primary storagestorage
volatilevolatile, it is lost , it is lost when computer’s when computer’s
power is power is turned offturned off
Memory
How do program instructions transfer in and out of RAM?Step 1. When you start the computer, certain operating system files are loaded into RAM from the hard disk. The operating system displays the user interface on the screen.
Operating system Operating system instructionsinstructions
Web browser Web browser instructionsinstructions
Operating system Operating system interfaceinterface
Web browser Web browser windowwindow
RAM
Step 2. When you start a Web browser, the program’s instructions are loaded into RAM from the hard disk. The Web browser window is displayed on the screen.
Word processing Word processing program instructionsprogram instructions
Word processing Word processing program windowprogram window
RAM
Web browser program Web browser program instructions are instructions are
removed from RAMremoved from RAM
Web browser Web browser window is no longer window is no longer
displayed on displayed on desktopdesktop
window is displayed on the screen.
Step 3. When you start a word processing program, the program’s instructions are loaded into RAM from the hard disk. The word processing program, along with the Web Browser and certain operating system instructions are in RAM. The word processing program window is displayed on the screen.
Step 4. When you quit a program, such as the Web browser, its program instructions are removed from RAM. The Web browser is no longer displayed on the screen.
Do not have toDo not have tobe rebe re--energizedenergized
as often asas often asDRAMDRAM
Most Most common common
typetype
Memory
What are two basic types of RAM chips?
Static Static
Must be Must be rere--energized energized
constantlyconstantly
Faster and Faster and more reliable more reliable than DRAM than DRAM
chipschips
RAM RAM (SRAM)(SRAM)
Dynamic Dynamic RAM RAM (DRAM)(DRAM)
Newer Type: Magnetoresistive RAM (MRAM)
1 Gb SDRAM Dual-in-line Memory Module
Two types of DIMMs : a 168-pin SDRAM module (top) and a 184-pin DDR SDRAMmodule (bottom).
30- (top) and 72-pin (bottom) SIMMs . Early 30-pin modules commonly had either 256 KB or 1 MB of memory.
http://www.maplin.co.uk/images/Full/a23aj.jpg
http://www.makeitsimple.com/articles/ramguide/ramguidep2.htm
Memory
Where does memory reside?� Resides on small circuit
board calledmemory module
� Memory slotson motherboard hold memory
dual inline memory module
motherboard hold memory modules memory chip memory slot
Memory
How much RAM does an application require?� Depends on the types of
software you plan to use
� For optimal performance, you performance, you need more than minimum specifications
Memory
How much RAM do you need?� Depends on type of applications you intend to run
on your computerRAM
Use
256 MB to 1 GB 512 MB to 1 GB 2 GB and up
• Home and business
users managing
• Users requiring more advanced
multimedia capabilities
• Power users creating
professional Web sites
personal finance
• Using standard
application software
such as word processing
• Using educational
or entertainment
CD-ROMs
• Communicating with
others on the Web
• Running number-intensive
accounting, financial, or
spreadsheet programs
• Using voice recognition
• Working with videos, music, and
digital imaging
• Creating Web sites
• Participating in video conferences
• Playing Internet games
• Running sophisticated
CAD, 3D design, or
other graphics-intensive
software
Memory
What is cache?
� L1 cache built into processor
� L2 cache slower but has larger
� Helps speed computer processes by storing frequently used instructions and data
� Also calledmemory cache
� L2 cache slower but has larger capacity
� L2 advanced transfer cache is faster, built directly on processor chip
� L3 cache is separate from processor chip on motherboard (L3 is only on computers that use L2 advanced transfer cache)
Memory Cache
� Cache speeds up processing time
� It stores frequently used instruction & data.
� When the processors needs them, it searches the memory in an order with greater delay in processing for each level of memory it must searchas the following order:as the following order:� L1 cache, then� L2 cache, then� L3 cache if it exists, then� RAM
� If the instruction or data is not found in memory, then it must search a slower speed storage medium(h/disk, CD, or DVD)
Memory
What is read-only memory (ROM)?
Memory chips that store Memory chips that store permanent data permanent data and instructionsand instructions
Nonvolatile memoryNonvolatile memory, it is not , it is not lost when computer’s lost when computer’s
power is turned offpower is turned off
Three types:Three types:EEPROMEEPROM
((eelectrically lectrically eerasable rasable pprogrammable rogrammable
FirmwareFirmware——ROM chips manufactured ROM chips manufactured with permanently written with permanently written data, instructions, data, instructions, or informationor information
eerasable rasable pprogrammable rogrammable rr eadead--oonly nly mmemory)emory)——
Type of PROM Type of PROM containing microcode containing microcode
programmer programmer can erasecan erase
PROMPROM((pprogrammable rogrammable
rr eadead--oonly nly mmemory)emory)——
Blank ROM Blank ROM chip onto which chip onto which a programmer a programmer
can write permanentlycan write permanentlyUse Microcode instructions to program a PROM chip
Erase microcode with anelectrical signal
Memory
What is flash memory?� Nonvolatile memory that can be erased electronically and rewritten
� Used with PDAs, digital cameras, smart phones, music players, digital voice recorders, printers, Internet receivers, and pagers
flash memory flash memory chips
USB port
from the computer
Portable media player
earphones cable
Memory
What is CMOS?
Complementary metal-oxide
semiconductor memory
Used in some RAM chips, flash
memory chips, and other types of memory chips
Uses battery power to retain
information when other power is
turned off
Stores date, time, and
computer’s startup
information
memory chips
The flash memory chips that store
computer’s startup information
often use CMOS technology
Memory
What is access time?� Amount of time it takes processor
to read data from memory� Measured in nanoseconds(ns),
one billionth of a second� It takes 1/10 of a second to blink
10 million operations = 1 blink
� It takes 1/10 of a second to blink your eye; a computer can perform up to 10 million operations in same amount of time
Term Speed
Millisecond One-thousandth of a second
Microsecond One-millionth of a second
Nanosecond One-billionth of a second
Picosecond One-trillionth of a second
Memory Access Time
� The access time (speed) of memory contributes to the overall performance of the computer.
� Accessing data in memory – 200,000 times faster than h/disk, because of h/disk’s mechanical motion.
� Access time also stated in MHz667 MHz DDR2 SDRAM� 667 MHz DDR2 SDRAM
� Divide 1 billion ns by the megahertz number� 667 MHz = (1,000,000,000/667,000,000)ns ≈ 1.5ns
� Manufacturers & retailers list a computer’s memory in terms of its size, not its access time.� 512 MB of SDRAM upgradeable to 4 GB
Expansion Slots and Adapter Cards
What is an adapter card?� A circuit board that
enhances system unit or provides connections to external devices calledperipherals – devices peripherals – devices connected to system unit & controlled by processor: modems, disk drives, printers, scanners, keyboards,…
� Also called anexpansion card
Expansion Slots and Adapter Cards
What is an expansion slot?� An opening, or socket,
on the motherboard that can hold an adapter card
� With Plug and Play, � With Plug and Play, the computer automatically configures cardsand other devices as you install them
Expansion Slots and Adapter Cards
Expansion Slots and Adapter Cards
What are PC cards, and flash memory cards?
PC card� thin removable flash memory device to
enable wireless Internet access to notebook computers
ExpressCard moduleExpressCard module� Next generation of PC Cards.� Removable flash memory device, to add
memory, storage, sound, fax/modem, communications, and other capabilities to computers
Expansion Slots and Adapter Cards
What are PC cards, and flash memory cards?
Flash memory card� allows users to transfer data from
mobile devices to desktop computers� storage capacity range: 32 MB – 8 GB� hot plugging – feature allows user to � hot plugging – feature allows user to
insert & remove the removable flash memory & other devices while computer is running
USB Flash drive � flash memory storage that plugs in a
USB port on a computer� 32 MB – 64 GB
Ports and Connectors
What are ports and connectors?� Port connects external devices to system unit� Connector joins cable to peripheral
� Male connector: have 1 or more pins
� Female connector: have matching hollows to accept the pins on a male connector
Ports and Connectors
What are different types of connectors?
Ports and Connectors
What is a serial port?� Transmits one bit of data at a
time� Connects slow-speed devices,
such as mouse, keyboard, modemmodem
� E.g. COM port
Ports and Connectors
What is a parallel port?� Connects devices that can
transfer more than one bit at a time, such as a printer
� Can transfer 8 bits of data (one byte) simultaneously (one byte) simultaneously through 8 separate lines in a single cable
Ports and Connectors
What are USB ports?
USB (universal serial bus) port can connect up to 127 different peripherals together
with a single connector type
USB (universal serial bus) port can connect up to 127 different peripherals together
with a single connector type
Third USB device connects to second USB
device, and so on
Third USB device connects to second USB
device, and so on
Second USB device connects
to first USB device
Second USB device connects
to first USB deviceFirst USB
device connects to USB port on computer
First USB device connects
to USB port on computer
Single USB port can be used to attach
multiple peripherals in a daisy chain
Single USB port can be used to attach
multiple peripherals in a daisy chain
PCs typically have six to eight USB ports
on front or back of the system unit
PCs typically have six to eight USB ports
on front or back of the system unit
Ports and Connectors
What are FireWire ports?
� Similar to a USB port� Connects multiple types of devices that require
faster data transmission speeds: digital video camera, color printer, scanners, digital cameras, camera, color printer, scanners, digital cameras, DVD drives,…
� Allows you to connect up to 63 devices together� Can use FireWire hub to attach multiple devices
to a single FireWire port
Ports and Connectors
What are special-purpose ports?
� MIDI (Musical Instrument Digital Interface) port
� eSata(external SATA – Serial Advances Technology Attachment) port– connect SATA h/disk to computer
� Not included in typical computer� Allow users to attach specialized peripherals or transmit data
to wireless devices
Attachment) port– connect SATA h/disk to computer
� SCSI(small computer system interface) port
� IrDA (Infrared Data Association) port– data transmission via infrared light waves; need to align the IrDA port on the device with IrDA port on the computer (like television remote control)
� Bluetooth port – Bluetooth technology uses radio waves to transmit data between two devices; do not need to be aligned with each other)
Ports and Connectors
Ports and Connectors
USB & FireWire ports are replacing traditional ports completely
Buses
What is a bus?� Channel that allows devices
inside computer to communicate with each other
� Data bus– transfers actual data� Address bus– transfers the info. where
the data should reside in memorythe data should reside in memory� System bus connects processor and RAM� Bus width determines number of bits
transmitted at one time (32-bit, 64-bit bus)� Word size is the number of bits processor
can interpret and execute at a given time; in most computers, the word size is the same as the bus width
� Bus clock speed: 1066 MHz
Memory chips
Buses
System Bus/Front Side Bus (FSB)� Part of motherboard� Connects processor to main memory
Expansion Bus� Allows processor to communicate with peripherals
PCI bus (Peripheral Component Interconnect bus)� PCI bus (Peripheral Component Interconnect bus)� PCI Express bus� Accelerated Graphics Port (AGP) bus� USB & FireWire bus� PC Card bus
FireWireBus
PCIBus
AGPBus
USBBus
Bays
What is a bay?� Open area inside system
unit used to install additional equipment
� Drive baystypically hold disk drivesdisk drives
� External drive bay – allow user to access the drive from outside the system unit: CD & DVD drives
� Internal drive bay – within system unit: h/disk
Power Supply
What is a power supply?
ConvertsAC Power
into
Fan keepssystem unit components
External peripherals might use an AC
adapter, which is an external power supply
DC Power cool
One end of AC adapter plugs in the wall outlet & the other end attached to the peripheral.
The AC adapter converts the AC power into DC power that the peripheral requires.
Mobile Computers and Devices
What is a mobile computer?� Notebook, weighing between 2.5 and 8 pounds, or
mobile device such as a PDA
Mobile Computers and Devices
What ports are on a notebook computer?
Mobile Computers and Devices
What ports and slots are on a tablet PC?
Putting It All Together
What are suggested processor, clock speed, and RAM requirements based on the needs of various types of users?
Keeping Your Computer Clean
Over time, the system unit collects dust – even in a clean environment
� Preventative maintenance requires a few basic products: