Discovering Computers Chapter 4 The Components of the System Unit.
-
Upload
gabriella-lever -
Category
Documents
-
view
224 -
download
1
Transcript of Discovering Computers Chapter 4 The Components of the System Unit.
2
Ch 4System Unit
Arithmetic Logic Unit
(ALU)
InputDevices
Ch 5
StorageDevices
Ch 7
OutputDevices
Ch 6
MemoryData Information
InstructionsData
Information
InstructionData
Information
Control Unit
Ch 1 – Introduction
Ch 2 – Internet & WWW
Ch 3 – Application Software
Ch 8 – System Software
PortsCardsBusesClockPowerDrives
3
What is the system unit?
Case that contains electronic components of the computer used to process data
5
Components inside the system unit?
Memory Clock Adapter
(extension) cards Sound card Video card
Drive bays Power supply Ports Buses
Processor
6
ProcessorThe processor, also called the central
processing unit (CPU), interprets and carries out the basic instructions that operate a computer
Contains a control unit and an arithmetic logic unit (ALU)
7
Control unit is the component of the processor that directs and coordinates most of the operations in the computer
Arithmetic logic unit (ALU) performs arithmetic, comparison, and other operations
8
For every instruction, a processor repeats a set of four basic operations,
which comprise a machine cycle
9
Processor
Control Unit
Memory
Step 1. Fetch Obtain program instruction from memory
Step 2. Decode Translate instruction into commands
Step 4. Store Write result to memory
Step 3. Execute Carry out command
ALU
10
The processor contains registers, that hold data and instructions
The processor contains circuits that perform instructions using data
System Clock
Generates regular electronic pulses, or ticks, that set operating pace of components of system unit
13
Each tick is a
clock cycle
Pace of system clock is clock speedClock speeds are
in the gigahertz (GHz- billion ticks per sec)
Processor speed is also measured in
millions of instructions per second (MIPS)
How speed of the processor is measured?
14
Clock speed (GHz) Instructions per sec (MIPS)
Instructions per 1 watt energy (in millions)
(MIPW)
15
What is pipelining?
Machine Cycle (without pipelining)
Machine Cycle (with pipelining)
Instruction 1
Instruction 2
Instruction 3
Instruction 4
CPU begins executing the second instruction before completing the first instruction
16
Doing LaundryAnn, Brian, Cathy, Dave each have one
load of clothes to wash, dry, fold, slash A B C D
°Dryer takes 30 minutes
°Folder takes 30 minutes
°Stasher takes 30 minutes
°Washer takes 30 minutes
17
Sequential Laundry
Sequential laundry takes 8 hours for 4 loads
Task
Order
B
C
D
A
30Time
3030 3030 30 3030 3030 3030 3030 3030
6 PM 7 8 9 10 11 12 1 2 AM
18
Pipelined Laundry
Pipelined laundry takes 3.5 hours for 4 loads
Task
Order
B
C
D
A
12 2 AM6 PM 7 8 9 10 11 1
Time303030 3030 3030
19
What is parallel processing?
Control Processor
Processor 1
Memory
Processor 2
Memory
Processor 3
Memory
Processor 4
Memory
Results combined
Using multiple processors simultaneously to execute a program faster
Requires special software to divide problem and bring results together
20
Single-core processor
Multi-core processor
One processor on a chip
More then one processor on a chip
22
Analog signals are continuous and vary in strength and quality
Digital signals are in one of two states: on or off
24
Eight bits grouped together as a unit are called a byte.
Each byte has a unique address.
Each of eight bits in a byte has a position
25
What a byte contains vs. what an output device will convey?
Contains: A sequence of 8 binary digits
Means: Number Character Instruction Sound pitch Color … Depending on device
26
Representing numbers Numbers have the most natural
presentation. Each bit of a byte has a value depending on the position of the bit in a byte.
For example byte 01010101 carries numeric value of 64+16+4+1 = 85
27
Coding systems to represent text data
ASCII—American Standard Code for Information Interchange
Unicode—coding scheme capable of representing allworld’s languages
Memory consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processing the data
What has to be stored?
30
The operating system and other system software
Application programs
Data being processed and the
resulting information
32
Memory consists of locations (bytes). Each location in memory has an address
The number of locations in memory is memory size.
It is measured in kilobytes (KB or K), megabytes (MB), gigabytes (GB), or terabytes (TB)
33
The system unit contains two types of memory:
Volatile memory
Loses its contents when power is
turned off
Example: RAM
Nonvolatile memory
Does not lose contents when
power is removed
Examples: ROM, flash memory
35
Adapter (Extension) Cards A flash memory card allows
users to transfer data from mobile devices to desktop computers
An PC card adds various capabilities to computers
38
Memory cache speeds the processes of the computer because it is faster than memory and stores repeatedly used information
39
Access time is the amount of time it takes the processor to read from memory. Measured in nanoseconds
40
Expansion slotholds an
adapter card
Adapter cardenhances
functions and
provides
connections to
peripherals
41
With Plug and Play, the computer automatically configures adapter cards and peripherals as you install them
42
Ports and Connectors
A port is the point at which a peripheral attaches to or communicates with a system unit (sometimes referred to as a jack)
A connector joins a cable to a port
46
Third USB device connects to second USB,
and so on
Third USB device connects to second USB,
and so on
Second USB device connects
to first USB
Second USB device connects
to first USBFirst USB device connects
to USB port
First USB device connects
to USB port
Single USB port can be used to attach
multiple peripherals
Single USB port can be used to attach
multiple peripherals
PCs typically have several USB ports
PCs typically have several USB ports
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
USB 2.0
48
Other types of ports include:
Firewire port
Bluetooth port
SCSI port
eSATA port
IrDA port
Serial port
MIDI port
49
What are special-purpose ports?
MIDI (Musical Instrument Digital Interface) port IrDA (Infrared Data Association) port Bluetooth port
Allow users to attach specialized peripherals or transmit data to wireless devices
51
A Bluetooth wireless port adapter converts a USB port into a Bluetooth port
A smart phone might communicate with a notebook computer using an IrDA port
52
What is a serial port?
Transmits one bit of data at a time
Connects slow-speed devices, such as mouse, keyboard, modem
53
What is a parallel port?
Connects devices that can transfer more than one bit at a time, such as a printer
54
Buses
What is a bus? Channel that allows devices
inside computer to communicate with each other
Bus width determines number of bits transmitted at one time
55
Bays
What is a bay? Opening inside system
unit used to install additional equipment
Drive bays typically hold disk drives
To see the online addition to the book click here