1. Lecture 1 Introduction Richard Gesick
Figures from Lewis, “C# Software Solutions”, Addison Wesley

2. Agenda Hardware and Software Analog & Digital
Binary and Data Representations
Introduction to Computer Architecture

3. Computer Processing Hardware Software The stuff you can touch
Programs and data

5. Modern Computer

6. Hardware and Software Hardware Software
the physical, tangible parts of a computer
keyboard, monitor, disks, wires, chips, etc.
Software
programs and data
a program is a series of instructions
A computer requires both hardware and software
Each is essentially useless without the other

7. Basic Computer Concepts
Hardware
Central Processing Unit
Memory and Storage Devices
Operating Systems
Application Software
Computer Networks and the Internet

8. Hardware A typical computer consists of:
CPU: executes the instructions of the program
Hard disk: stores instructions and data so program can be loaded into memory and executed
Memory unit: stores the program instructions and data while executing
Keyboard and mouse: used for data input
Monitor: used to display output from a program
Other accessories / peripherals

10. CPU and Main Memory Chip that executes program commands
Intel Pentium 4
Sun ultraSPARC III
Central
Processing
Unit
Main
Memory
Primary storage area for programs and data that are in active use
Synonymous with RAM

11. Secondary Memory Devices
Information is moved
between main memory
and secondary memory
as needed
Secondary memory
devices provide
long-term storage
Central
Processing
Unit
Main
Memory
Hard disks
Floppy disks
ZIP disks
Writable CDs
Writable DVDs
Tapes
Floppy Disk
Hard Disk

12. Input / Output Devices Monitor I/O devices facilitate Central
Keyboard
I/O devices facilitate
user interaction
Central
Processing
Unit
Main
Memory
Floppy Disk
Hard Disk
Monitor screen
Keyboard
Mouse
Joystick
Bar code scanner
Touch screen

13. The Central Processing Unit
A CPU is on a chip called a microprocessor
It continuously follows the fetch-decode-execute cycle:
fetch
Retrieve an instruction from main memory
decode
Determine what the
instruction is
execute
Carry out the
instruction

14. The Central Processing Unit
The CPU contains:
Performs calculations and makes decisions
Arithmetic / Logic Unit
Coordinates processing steps
Control Unit
Small storage areas
Registers

15. Central Processing Unit (CPU)
Arithmetic Logic Unit: performs integer arithmetic and logical operations
Floating-point Unit: performs floating-point operations
Hardware registers: store data and memory addresses
Instruction pointer: keeps track of current instruction to execute
Examples: Intel Pentium 4, Sun Microsystems SPARC, IBM PowerPC

16. Processor Instruction Set
Move data from one location to another
Perform a calculation
Change the sequence of instructions to execute (the flow of control)

17. CPU Speed Rated in MHz or GHz In one clock cycle, a CPU
fetches an instruction from memory,
decodes the instruction, or
executes the instruction
Pipelining allows overlap of operations to improve performance
2-Ghz CPU can execute 2 billion instructions per second

18. Memory or Storage Devices
Memory consists of cells that hold one bit.
A bit's value can be 0 or 1
A byte is 8 binary digits (bits)

19. From Dell:

20. Memory has width
(word size)
Memory has
capacity

21. Memory
Main memory is volatile - stored information is lost if the electric power is removed
Secondary memory devices are nonvolatile
Main memory and disks are direct access devices - information can be reached directly
The terms direct access and random access often are used interchangeably
A magnetic tape is a sequential access device since its data is arranged in a linear order - you must get by the intervening data in order to access other information

22. Software Categories Operating System Shell Applications
Resource manager/coordinator
Shell
Interface between the OS and the user and applications
Applications
What the user sees

24. Operating System Software
boots when computer is turned on and runs continuously
Controls the peripheral devices (disks, keyboard, mouse, etc.)
Supports multitasking (multiple programs executing simultaneously)
Allocates memory to each program
Prevents one program from damaging another program
Example: Microsoft Windows, Linux

25. Application Software Written to perform specific tasks
Runs "on top of" operating system
Examples: word processor, spreadsheet, database management system, games, Internet browser, etc.

26. Client/Server What is the OS here? What is the application?
Where does data live?
How to we coordinate the application among many users?

27. What is better?

28. Analog information is continuous
Digital information is discrete

29. Sampling induces losses
Humans can hear 20Hz-20kHz
44.1 kHz typical sample rate (CD)
Sample rate >= double frequency Nyquist (1924)

31. Why do we care? Computers are dumb
They’re just dumb at a really fast rate
2.8gHz computer can perform 2.8 billion operations per second
Computers only see in binary (0/1)
Anything we see as meaningful is strings of 0s and 1s

32. Digital Information Computers store all information digitally:
numbers
text
graphics and images
video
audio
program instructions
In some way, all information is digitized - broken down into pieces and represented as numbers

33. Representing Text Digitally
For example, every character is stored as a number, including spaces, digits, and punctuation
Corresponding upper and lower case letters are separate characters
H i , H e a t h e r .

34. Binary Numbers
Once information is digitized, it is represented and stored in memory using the binary number system
A single binary digit (0 or 1) is called a bit
Devices that store and move information are cheaper and more reliable if they have to represent only two states
A single bit can represent two possible states, like a light bulb that is either on (1) or off (0)
Permutations of bits are used to store values

35. Data Representation Binary Numbers Hexadecimal Numbers
Expressed in base 2 system (two values are 0 and 1)
Hexadecimal Numbers
Base-16 system used as shorthand for binary numbers
Representing Characters with the Character Set

36. Converting & Bases
Binary
Oct
Dec
Hex

37. Binary Equivalents of Decimal Numbers
Decimal Binary Equivalent

38. Powers of 2 Decimal Decimal 20 1 28 256 21 2 29 512 22 4 210 1024
Notice with each additional bit, it doubles the possible number of values.

40. Decimal (base 10) numbers
A decimal number can be represented as the sum of powers of 10 (the base) with coefficients in the base 10 alphabet (0 - 9)
For example:
2485 =
2485 = 2 * * * * 1
2485 = 2 * * * * 100

41. Converting from Binary to Decimal
= ?

42. Converting From Decimal to Binary
Just as a decimal number can be represented as a sum of powers of 10 (the base) with coefficients in the base 10 alphabet (0 to 9),
A decimal number also can be represented as the sum of powers of 2 (the base of the binary system) with coefficients in the base 2 alphabet (0 and 1)
So we need an algorithm to do that

43. Converting From Decimal to Binary
Find the largest power of 2 that is smaller than or equal to the decimal number
Subtract that number from the decimal number
Insert 1 in binary number for position equivalent to that power of 2
Repeat 1 - 3, until you reach 0

44. Example: convert 359 to binary
Largest power of 2 that is smaller than 359 is 256 (28)
= 103
so 359 = 28*
Largest power of 2 that is smaller than 103 is 64 (26)
= 39
so 359 = 28*1 + 26*1 + 39
(continued on next slide)

45. Example: convert 359 to binary
Largest power of 2 that is smaller than 39 is 32 (25)
= 7
so 359 = 28*1 + 26*1 + 25*1 + 7
Largest power of 2 that is smaller than 7 is 4 (22)
7 - 4 = 3
so 359 = 28*1 + 26*1 + 25*1 + 22*1 + 3
(continued on next slide)

46. Example: convert 359 to binary
Largest power of 2 that is smaller than 3 is 2 (21)
3 - 2 = 1
so 359 = 28*1 + 26*1 + 25*1 + 22*1 + 21*1 + 1
Largest power of 2 that is smaller than or equal to 1 is 1 (20)
1 - 1 = 0, so we are finished

47. Our results Finally, insert missing powers of 2 with coefficient 0.
Thus, 359 =
28*1 + 27*0 + 26*1 + 25*1 + 24*0 + 23*0 + 22*1 + 21*1 + 20*1
Removing powers of 2, we get: Or

48. Hexadecimal Numbers Base-16 number system
Uses digits and letters A - F
One hexadecimal digit can express values from 0 to 15
For example: C represents 12
Thus, one hexadecimal digit can represent 4 bits

49. Hexadecimal - Binary Equivalents
Hex Binary Hex Binary A B C D E F

50. Examples Binary number: 0001 1010 1111 1001 Hex equivalent: 1 A F 9
Hex equivalent: B B E

51. Practice with Number Systems
1002 = ? = ? = ?10 3A1B16 = ?2

52. Practice with Number Systems
1002 = 416 =
= 42310
3A1B16 =

53. The Unicode Character Set
Each character stored as 16-bits
Maximum number of characters that can be represented: 65,536 (216) (w_char )
ASCII character set (used by many programming languages) stores each character as 7 bits (maximum number of characters is 128).
For compatibility, first 128 characters of Unicode set represent the ASCII characters

54. ASCII American Standard Code for Information Interchange
Char Dec Oct Hex | Char Dec Oct Hex | Char Dec Oct Hex | Char Dec Oct Hex (nul) x00 | (sp) x x40 | ` x60 (soh) x01 | ! x21 | A x41 | a x61 (stx) x02 | " x22 | B x42 | b x62 (etx) x03 | # x23 | C x43 | c x63 (eot) x04 | $ x24 | D x44 | d x64 (enq) x05 | % x25 | E x45 | e x65 (ack) x06 | & x26 | F x46 | f x66 (bel) x07 | ' x27 | G x47 | g x67 (bs) x08 | ( x28 | H x48 | h x68 (ht) x09 | ) x29 | I x49 | i x69 (nl) x0a | * x2a | J x4a | j x6a (vt) x0b | x2b | K x4b | k x6b (np) x0c | , x2c | L x4c | l x6c (cr) x0d | x2d | M x4d | m x6d (so) x0e | x2e | N x4e | n x6e (si) x0f | / x2f | O x4f | o x6f (dle) x10 | x30 | P x50 | p x70 (dc1) x11 | x31 | Q x51 | q x71 (dc2) x12 | x32 | R x52 | r x72 (dc3) x13 | x33 | S x53 | s x73 (dc4) x14 | x34 | T x54 | t x74 (nak) x15 | x35 | U x55 | u x75 From: