1. COMP 14 Introduction to Programming
Miguel A. Otaduy
May 12, 2004
Hand out syllabus if necessary
Intro myself again
Go through class roll.

2. …from Last Time Homework 1 due Tomorrow
Fill in form with personal info
Getting started with jGRASP
Compile and Run test programs
Any problems?
Disable test for new versions

3. Today (ch. 1) Parts of the computer Binary numbers
hardware vs. software
CPU and memory
Binary numbers
What is an algorithm?
Once we know these 3 elements we can actually start coding our own programs.

4. Reading Check-Up
hardware
- computer components including the CPU, main memory, I/O devices, and secondary storage
- the brain of the computer, containing the CU, PC, IR, ALU, and ACC
- computer instructions to solve a problem
The digits 0 and 1 are called
or the shortened term
CPU
program
Digits that can only take the values 0 and 1.
binary digits
bits

5. Hardware vs. Software Hardware Software
A computer is made up of hardware and software
Hardware
Software
CPU
ex: 1 GHz Pentium III
input/output
keyboard
monitor
network card
main memory
ex: 256 MB RAM
secondary memory
ex: 20 GB hard drive
operating systems
Windows XP
Mac OS X
applications
games
Microsoft Word
Internet Explorer

6. Hardware Organization
CPU
memory
motherboard
hard drive

7. Central Processing Unit CPU
Control Unit (CU)
"the brain" of the CPU
Program Counter (PC)
points to the next instruction to be executed
Instruction Register (IR)
holds the currently executing instruction
Arithmetic Logic Unit (ALU)
carries out all arithmetic and logical ops
Accumulator (ACC)
holds the results of the operations performed by the ALU CU
fetch and decode instructions
control the flow of info between CPU and main memory
control the operation of the other CPU components

8. Main Memory Ordered sequence of cells AKA Random Access Memory (RAM)
Directly connected to the CPU
All programs must be brought into main memory before execution
When power is turned off, everything in main memory is lost

9. Main Memory With 100 Cells
Each memory cell has a numeric address, which uniquely identifies it

10. CPU and Main Memory
All programs must be brought into main memory before execution
Chip that executes
program instructions
(processor)
Primary storage area
for programs and data
that are in active use
(RAM)

11. Secondary Storage Provides permanent storage for information
Retains information even when power is off
Examples of secondary storage:
Hard Disks
Floppy Disks
ZIP Disks
CD-ROMs
Tapes

12. Secondary Storage Secondary memory devices provide long-term storage
Information is moved
between main memory
and secondary memory
as needed

13. Input Devices
Definition: devices that feed data and computer programs into computers
Examples:
Keyboard
Mouse
Secondary Storage

14. Output Devices
Definition: devices that the computer uses to display results
Examples:
Printer
Monitor
Secondary Storage

15. Input/Output Devices
I/O devices facilitate user interaction

16. Hardware Components

17. Opening MS Word Use the mouse to select MS Word
The CPU requests the MS Word application
MS Word is loaded from the hard drive to main memory
The CPU reads instructions from main memory and executes them one at a time
MS Word is displayed on your monitor

18. Questions - points to the next instruction to be executed
- a unique location in memory
- stores information permanently
Instructions executed by the CPU must be first loaded to
program counter (PC)
address
secondary storage
main memory

19. Software Categories Operating System Application
controls all machine activities
provides the user interface to the computer
first program to load when a computer is turned on
manages computer resources, such as the CPU, memory, and hard drive
examples: Windows XP, Linux, Mac OS X
Application
generic term for any other kind of software
examples: word processors, missile control systems, games

20. Operating System (OS)
OS monitors overall activity of the computer and provides services
Written using programming language
Example services:
memory management
input/output
storage management

21. Application Programs Written using programming languages
Perform a specific task
Run by the OS
Example programs:
Word Processors
Spreadsheets
Games

22. Questions
Classify the following pieces of software as operating system or application:
Microsoft Windows 2000
Microsoft PowerPoint
Linux
Your COMP 14 programs OS
app OS
app

23. It’s All About Data Software is data
numbers, characters
instructions, programs
Hardware stores and processes data
read, write
add, subtract, multiply, divide

24. Analog vs. Digital Analog Digital continuous wave forms
ex: sound, music on an audio tape
Digital
the information is broken down into pieces, and each piece is represented separately
represented as series of 0 and 1
0 - low voltage
1 - high voltage
can be copied exactly
ex: music on a compact disc
Two basic ways to store and manage data
Digital
electrical signal
digital is used inside the computer
at its lowest-level, the computer only understands 0 and 1

25. Representing Text Digitally
All information in a computer is digitized, broken down and represented as numbers.
H i , H e a t h e r .
Corresponding upper and lower case letters are separate characters.

26. Language of a Computer
Machine language: the most basic language of a computer
A sequence of 0s and 1s
binary digit, or bit
sequence of 8 bits is called a byte
Every computer directly understands its own machine language
why can't Windows programs run on Apple computers?
Once we digitize something, we have to convert those numbers to binary (the computer's language)

27. Bit Permutations 1 bit 1 2 bits 00 01 10 11 3 bits 000 001 010 011 1001
2 bits 00 01 10 11
3 bits
000
001
010
011
100
101
110
111
4 bits
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Each additional bit doubles the number of possible permutations

28. Bit Permutations Each permutation can represent a particular item
There are 2N permutations of N bits
N bits are needed to represent 2N unique items
1 bit ?
2 bits ?
3 bits ?
4 bits ?
5 bits ?
How many
items can be
represented by
21 = 2 items
22 = 4 items
23 = 8 items
24 = 16 items
25 = 32 items

29. Binary Numbers N bits to represent 2N values
N bits represent values 0 to 2N-1
Example: 5 bits
32 unique values (0-31)
00000 = 0
11111 = 31

30. Decimal to Binary 114 1110010 Place Digit Value 26 1 64 25 1 32

31. Questions Binary Numbers
What’s the maximum value a 6-bit number can represent?
What’s the decimal representation of ?
What’s the binary representation of 35? 63
58 =
5 minutes to work on these.
Then show the calculator in the computer.
100011

32. Storage Capacity
Every memory device has a storage capacity, indicating the number of bytes (8 bits) it can hold
Various units:
Unit Symbol Number of Bytes
kilobyte
megabyte
gigabyte
terabyte
KB 210 = 1024
MB 220 (over 1 million)
GB 230 (over 1 billion)
TB 240 (over 1 trillion)

33. Programming Languages Evolution
Early computers programmed in machine language (only 0s and 1s)
Assembly languages were developed to make programmer’s job easier
Assembler: translates assembly language instructions into machine language

34. Assembly and Machine Language

35. Programming Languages Evolution
High-level languages make programming easier
Closer to spoken languages
Examples:
Basic
FORTRAN
COBOL
C/C++
Java

36. From Java to Machine Language
Computers understand only 0 and 1 (machine language)
Compiler translates source code into machine code
Java compiler translates source code (file ending in .java) into bytecode (file ending in .class)
bytecode is portable (not machine-specific)
Java interpreter reads and executes bytecode
different Java interpreters for different types of CPUs and operating systems (OS)
Intel/Windows, Motorola/Mac OS X, Intel/Linux

37. Problem Solving The purpose of writing a program is to solve a problem
The general steps in problem solving are:
understand the problem
dissect the problem into manageable pieces
design a solution
consider alternatives to the solution and refine it
implement the solution
test the solution and fix any problems that exist

38. Algorithm
Sequence of instructions used to carry out a task or solve a problem
May be written in either English or pseudocode
outline of a program that could be translated into actual code
May need refinement as you work
Always write out your algorithm before you begin programming

39. Problem-Analysis-Coding-Execution
most important step
without
computer
with
computer

40. Algorithm Design Example
Problem: Convert change in cents to number of half-dollars, quarters, dimes, nickels, and pennies to be returned.
Example:
given 646 cents
number of half-dollars: divide 646 by 50
quotient is 12 (number of half-dollars)
remainder is 46 (change left over)
number of quarters: divide 46 by 25
quotient is 1 (number of quarters)
remainder is 21 (change left over)
number of dimes, nickels, pennies
result: 12 half-dollars, 1 quarter, 2 dimes, 0 nickels, 1 penny

41. Resulting Algorithm Get the change in cents
Find the number of half-dollars
Calculate the remaining change
Find the number of quarters
Find the number of dimes
Find the number of nickels
The remaining change is the number of pennies.

42. Exercise
Execution of c=2*a+b in a computer

43. To do
Read ch. 2
Exercises 10 & 11 in ch. 1 (algorithm design)

44. What’s Ahead... Java Basics Homework 1 due tomorrow
Homework 2 assigned tomorrow
Quiz Friday: computers and Java basics