1. Hardware: Input, Processing, and Output Devices
Chapter 3

2. Chapter Topics Computer system components
The power, speed, and capacity of processing and main memory devices.
Access methods, capacity and portability of secondary storage devices.
Input & output devices
The popular classes of computer systems

3. Hardware: Typical System
Printer (output)
Monitor (output)
Speakers (output)
Mouse (input)
Keyboard (input)
System unit (processing and secondary storage)

4. Computer Hardware CPU Memory System Unit Input Devices Storage Output
Peripherals
“Ports”
“Motherboard”
“Expansion
Slots”

5. On the Motherboard A “motherboard” CPU A RAM chip A “firewire” card
Pins to attach to
The motherboard
Expansion slots

6. CPU
Fetch
Decode
Execute
Write-back
Memory Registers
ALU
Control
Unit

7. CPU Control Unit Arithmetic/logic Unit (ALU) Registers Maintains order
Controls CPU activity
Directs sequence of operations
Arithmetic/logic Unit
(ALU)
Manipulates data
Performs arithmetic computations
Performs logical operations
Registers
Temporary storage areas for instructions or data
offer the advantage of speed
work under the direction of the control unit to accept, hold, and transfer instructions or data

8. Machine Cycle Fetch Decode Write-back Execute Instruction Cycle
Execution Cycle

9. Machine Cycle Time Measures
Microseconds (1 millionth)
Nanoseconds (1 billionth)
Picoseconds (1 trillionth)
MIPS (Millions of Instructions Processed per Second)

10. How fast is a Nanosecond?
If one nanosecond is..
One mile
One person
One minute
One square mile
Then one second is equivalent to …
2000 trips to the moon and back
Population of China and the U.S.
1900 years
17 times the land are of the world

11. Data Bus Fetch Decode Execute Write-back “Word sizes” 8 bits 16 bits

12. Processing Characteristics
Clock speed: electronic pulses affecting machine cycle time
Hertz: one cycle (pulse) per second
Megahertz (MHz): millions of cycles per second
Microcode: internal, predefined elementary operations in a CPU

13. Microcode Instruction Sets
Complex instruction set computing: CPU contains many microcode instructions
Reduced instruction set computing (RISC): Minimal set of microcode instructions
Very Long Instruction Word (VLIW): Each microcode instruction is longer and does more.

14. Multiprocessing More than one CPU is present
Tasks are divided among CPUs in true “parallel processing”
Parallel processing uses multiple processors to execute instructions in concert.

15. Parallel Processing
Control CPU
Combined Results

16. Physical Characteristics of the CPU
Digital circuits on chips
Electrical current flows through silicon
Moore’s Law states that transistor density of chips will double every 18 months

17. Memory Characteristics and Functions

18. Memories Random Access Memory (RAM) ROM CPU Secondary Primary Cache
System Bus
External
Storage
Devices
Expansion slots
I/O Bus
ROM

19. ROM Chip and BIOS ROM stands for Read Only Memory
ROM is a non-volatile memory on a chip
The ROM chip contains
Basic input/output system BIOS
The BIOS has the instructions necessary
to start up your computer

20. RAM RAM stands for Random Access Memory
RAM is a volatile memory on a chip
RAM chips store information in “addresses”
that can be accessed directly and quickly

21. Storage Media Storage devices retain data when power is switched off
Storage devices are slower than memory devices like RAM

22. Memory Versus Storage Memory Storage
A temporary holding place for data and instructions
Consists of one or more chips on the motherboard
Sometimes called primary storage
Storage
The media on which data, instructions, and information are kept, as well as the devices that record and retrieve these items
Storage also called secondary storage, auxiliary storage, permanent storage, or mass storage
Storage is nonvolatile

23. Managing Memory Remember the “Machine Cycle?” Page is Decoding and
“swapped in”
Decoding and
Execution
Page is
“swapped out”

24. Starting Up BIOS read 2. OS “kernel,” or from ROM supervisor program
becomes
memory resident.
3. CPU reads and
executes instructions

25. Storage Capacity
Storage Term
Number of bytes
Abbreviation
The number of bytes (characters) a storage medium can hold
Manufacturers use many terms to define the capacity of storage media
Kilobyte KB
1 thousand
Megabyte MB
1 million
Gigabyte GB
1 billion
Terabyte TB
1 trillion
Petabyte PB
1 quadrillion

26. Data Representation
A computer circuit represents the 0 or the 1 electronically by the presence or absence of an electronic charge.
Binary Digit (Bit): Electronic State On
Off
Binary system: two unique digits, 0 and 1
Bit: the smallest unit of data the computer can represent
A byte: a group of 8 bits: represents a single character in the computer

27. Bits and Bytes Byte Eight bits Kilobyte - 1 thousand bytes
Megabyte - 1 million bytes
Gigabyte - 1 billion bytes
Terabyte trillion bytes

28. Coding Schemes
A byte provides enough different combinations of 0s and 1s to represent 256 individual characters.
A coding scheme: the defined combinations of 0s and 1s that represent characters by patterns
ASCII(The American Standard Code for Information Interchange)
ASCII represents 0-9, upper and lower case A-Z, and English language punctuation in byte code
EBCDIC (The Extended Binary Coded Decimal Interchange Code)
Unicode

29. Data Storage Hierarchy
DOG…..
CAT….
FOX….
File
Record
DOG, FOUR LEGS, TWO EARS
Field
DOG
Character (byte)
D O G
Bits

30. Storage Modes Direct(Random) Access Sequential
records can be retrieved in any order
Faster (nanoseconds)
Usually more expensive
Sequential
records must be retrieved in order
Slower (milliseconds)
Less expensive
The dog barked. T H E D O G . Th
bar d og k ed e

31. Sequential access versus Direct access
Method used for floppy disks, hard disks, and compact discs
Also called random access
You can locate a particular data item or file immediately, without having to move consecutively through items stored in front of the desired data item or file
Faster
Used as the primary method of storage
Sequential access
Method used for tape
Reading and writing data consecutively
You must forward or rewind the tape to a specific point to access a specific piece of data
Much slower
Utilized most often for long-term storage and backup

32. Storage Technologies Magnetic Optical
Read/write head uses electrical impulses to create or interpret patterns of magnetic impulses
Floppy disks
Hard disks
Tape
Optical
Laser beam creates or reads non-reflective pits and reflective land areas
CDs
DVDs
Ancient DecTape
systems

33. Disks
Read/Write
Head
Sector
Cluster

34. Access time
cost
less expensive
more expensive
speed
faster
slower
Memory (RAM)
The amount of time it takes the device to locate an item on a disk
Defines the speed of a disk storage device
Hard Disk
Compact Disc
Floppy Disk
Tape

35. CD-R & CD-RW CD-R (compact disc-recordable)
You write on the CD-R using a CD recorder or a CD-R drive and special software
The CD-R drive can read and write both audio CDs and standard CD-ROMs
You cannot erase the disc’s contents
Most CD-ROM drives can read a CD-R
CD-RW (compact disc-rewritable)
An erasable disc you can write on multiple times
You must have CD-RW software and a CD-RW drive

36. DVD-ROM (digital video disc-ROM)
An extremely high capacity compact disc capable of storing from 4.7 GB to 17 GB
You must have a DVD-ROM drive or DVD player to read a DVD-ROM
Looks just like a CD-ROM but data, instructions, and information is stored in a slightly different manner to achieve a higher storage capacity

37. Magnetic Tapes
A magnetically coated ribbon of plastic capable of storing large amounts of data and information at a low cost
A tape drive reads from and writes data and information on a tape
Older computers used reel-to-reel tape drives
A tape cartridge is a small, rectangular, plastic housing for tape used in today’s tape drives
Used by business and home users to backup personal computer hard disks
Both external and internal tape units for personal computers
Larger computers use tape cartridges mounted in a separate cabinet called a tape library

38. Storage techniques used in an enterprise system
Storage area network (SAN): A high-speed network that connects storage devices
Tape library: A high-capacity tape system that works with multiple tape cartridges for storing backups of data, information, and instructions
RAID system: Ensures that data is not lost if one drive fails
Server: Stores data, information, and instructions need by users on the network
CD-ROM jukebox: Holds hundreds of CD-ROMs that can contain application programs and data. Also called a CD-ROM server
Internet backup: Stores data, information, and instructions on the Web

39. RAID Redundant array of independent disks
A type of hard disk system that connects several smaller disks into a single unit that acts like a single large hard disk
More reliable than a traditional disk system but quite expensive
RAID duplicates data, instructions, and information to improve data reliability

40. How does RAID work?
Level 1, called mirroring, has one backup disk for each disk
Levels beyond level 1 use a technique called striping, which splits data, instructions, and information across multiple disks in the array
Mirroring (RAID Level 1)
Striping

41. Additional Devices and Media
Memory Cards
A thin, credit card-sized device
Fits into a PC Card slot on a notebook other personal computer
Different types and sizes add storage, additional memory, communications, and sound capabilities to a computer
Three types of PC Card
Advantage of a PC Card for storage is portability between systems
Flash memory
Also called flash ROM or flash RAM
Nonvolatile memory that can be erased electronically and reprogrammed
Stores data and programs on many handheld computers and devices
Flash memory cards store flash memory on removable devices instead of chips

42. Input and Output
Device Driver
software
Interrupts

43. Input devices What is input? Types of input
Any data or instructions you enter into the memory of the computer
Users can input data and instructions in a variety of ways
Types of input
Data: A collection of raw unprocessed facts, figures, and symbols
Instructions: Programs, Commands, User responses

44. Data Data can be human or machine readable
Data entry converts human readable data into machine-readable form
Data input transfers machine-readable data into the system
Source data automation

45. Input Devices Personal computer input devices
Keyboard
Mouse
Voice-recognition devices
Digital cameras
Terminals

46. Input Devices Scanning devices Optical data readers Bar code scanners
MICR devices
POS (point-of-sale) devices
Pen input devices
Light pens
Touch screens

47. Output Devices Monitors Printers Plotters
Cathode Ray Tubes (CRTs)
Liquid Crystal Displays (LCDs)
Active matrix
Passive matrix
Printers
Plotters
Computer Output Microform (COM)
Music Devices

48. What is a CRT monitor?
Contains a cathode ray tube (CRT), a large sealed, glass screen
The screen is coated with tiny dots of phosphor material
A pixel, or picture element, is a single point in an electronic image
Three dots (red, blue, and green) combine to make up each pixel
cathode ray tube
screen
CRT monitor

49. What is a liquid crystal display (LCD) monitor?
A type of flat-panel display
Uses liquid crystals between two sheets of material to present information on a screen
An electric current passes through the crystals which creates the images on the screen

50. What is display resolution?
Describes the sharpness and clearness of an image
Resolution of a display device stated as dots, or pixels
800 x 600 typically the standard
800 horizontal pixels
600 vertical pixels
1280 x 1024 maximum resolution of most monitors
Total of 480,000 pixels on screen
2048 x 1536 maximum for high-end monitors

51. What is a video card?
Converts digital output from the computer into an analog video signal
Sends the signal through a cable to the monitor
Controls how the display device produces the picture
Also called a graphics card or video adapter

52. How does video travel from the processor to a CRT monitor?
Step 1: The processor sends digital video data to the video card.
Step 2: The video card’s digital-to-analog converter (DAC) converts the digital video data to an analog signal.
Step 3: The analog signal is sent through a cable to the CRT monitor.
Step 4: The CRT monitor separates the analog signal into red, green, and blue signals.
Step 5: Electron guns fire the three color signals to the front of the CRT.
Step 6: An image displays on the screen when the electrons hit phosphor dots on the back of the screen.

53. What is bit depth? 28 = 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 = 256 colors
8-bit video card (8-bit color)
Uses 8 bits to store information about each pixel
Can display 256 different colors
28 = 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 = 256 colors
What is bit depth?
The number of bits a video card uses to store information about each pixel
Also called the color depth
Determines the number of colors a video card can display
The greater the number of bits, the better the resulting image
24-bit video card
Uses 24 bits to store information about each pixel
Can display 16.7 million colors
224 = million colors

54. What are various video standards?
The Video Electronics Standards Association (VESA) develops video standards

55. Computer System Types Network computer Personal computer Workstation
Midrange computer
Mainframe computer
Supercomputer

57. Selecting and Upgrading Computer Systems
Computer system architecture: the configuration of a computer system’s hardware components