1. Introduction to Computer Programming1
Introduction to Computer Programming

2. Overview What is a computer? Components Units of storage Encoding
Hardware
Software
Units of storage
Encoding

3. What is a computer?
A computer is a collection of electrical and mechanical devices that can accept input and provide output via input and output devices respectively
Processes data (input) to produce a result (output)
Very fast execution of simple instructions
Simple; example logic true and false, loops
Combination of simple instructions generate more complex ones

4. Figure of a motherboard
Components
Figure of a motherboard
Hardware
Internal devices
Motherboard
Interconnect internal devices
Power supply
Central Processing Unit (CPU)
Speed in Hertz (Hz, cycles per second)
Normally it is used the clock speed, in
the order of GHz (1,000,000,000 Hz)
CPU
FDD: Floppy Disk Drive
The CPU(s) needs to be close to motherboard to reduce distance to other devices like RAM that means bigger faster (quicker access) and less power consumption (heat produced – less important given the lengths considered)

5. Components Hardware Internal devices (cont.) Memory Volatile memory
Random Access Memory (RAM)
Persistent memory
Read Only Memory (ROM)
Hard drive
Data storage device (read/write)
RAM
Hard drive
FDD: Floppy Disk Drive
The CPU(s) needs to be close to motherboard to reduce distance to other devices like RAM that means bigger faster (quicker access) and less power consumption (heat produced – less important given the lengths considered)

6. Components CPU Power and data cables Power supply Ventilation Memory
Speaker
Ventilation
Memory
Hard drive
RAM
Power supply
Motherboard

7. Components Hardware (cont.) External also called peripherals
Input; provides data to the computer
Keyboard
Mouse
Touch screen ...
Output; gets data from the computer
Monitor
Printer
Scanner
External Storage Device
Speakers
Exercise: What other device is input and output?
Touch screen and external memory device (e.g. USB stick, external mass storage device) are both input and output devices.

8. Components Software Basic Input/Output System (BIOS)
Instructions and setup for how a system should boot and how it operates
Operating System (OS)
Consists of programs that manage the computer hardware and resources, and provides common services for efficient execution of applications
Programs
Are a sequence of instructions written to perform a specified task
Mainly the BIOS the following functions:
POST – Tests the computer hardware, ensuring hardware is properly functioning before starting process of loading the operating system.
Bootstrap Loader - Processes the location of the Operating System. If Operating System located, BIOS will pass the control to it.
BIOS - Software / Drivers that interface between the operating system and your hardware.
BIOS / CMOS Setup - It’s a configuration program that allows to configure hardware settings including system settings such as computer passwords, time, and date.
BIOS and OS in machine language (has been compiled) to make them faster and more efficient.
Programs may not like in the case of Java, we’ll see more in future lectures.

9. Units of storage Units of storage Bit Bytes Kilobytes (KB)
Two valid values 0 or 1
Bytes
8 bits
Represents numbers from -128 to 127 (or 0 to 255)
Kilobytes (KB)
1KB is 1024 Bytes
Megabytes (MB)
1MB is 1024 KB
Gigabytes (GB)
1GB is 1024 MB
Terabytes (TB)
1TB is 1024 GB
Machines represent integers with 4 Bytes (32 bits) or 8 Bytes (64 bits)
4 Bytes maximum integer represented is – to (normally used highest bit to represent the sign)

10. Encoding Encoding is the way a number may be represented
In the case of integers
Decimal
Ten values are used in the representation
Uses 0, 1, ..., 9 to represent the number
Binary
Two values are used in the representation
Uses 0 and 1 to represent the number
Hexadecimal
Sixteen values are used in the representation
Uses 0, 1, ..., 9, a, b, ..., f to represent the number
There are more representations, as octal, but the most used are decimal, binary and hexadecimal.
0 to 9 normally called digits

11. Encoding Binary 16 + 1 17 = Decimal Binary
Byte
Decimal
Binary
(base 2)
Bit
Bit value 1 16 1 1 8 + 1 17 16 1 16 1
128 1 32 1 2 1 64 1 4
128 64 32 16 8 4 2 1 8
Bit index 7 6 5 4 3 2 1 20 21 22 27 23 26 25 24
Bit exponential representation
/**
* Builds the binary representation of the provided number. *
iValue the number to represent in binary.
the binary representation of the provided number. */
public static String toBin(final int iValue) {
final String alpha = "01"; // representing values
final int iRemainder = (iValue % 2); // amount left over
String strBin;
if (iValue == iRemainder) {
// Last element in the representation
strBin = alpha.charAt(iRemainde);
} else {
// Build next element in the representation
strBin = toHex(iValue / 2) + alpha.charAt(iRemainder); }
return strBin;
} // toBin() 17 =
   255

12. Encoding
Hexadecimal 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 a b c d e f
Dec Hex
Divide by 16
Hexadecimal (base 16) 17 16 1 16 1
Byte 1 1 1
Divide by 16
255 5 16 16 1 5
255
Dec f ff
Hex 9
One Byte is represented by two hexadecimal values, example ff for 255 or 7f for 127.
Red Green Blue (RGB) colour representation, where each colour is represented in a byte in hexadecimal; white ffffff, red ff0000, green 00ff00 and blue 0000ff. The other values refers to mix of the tree main colours, red green and blue.
/**
* Builds the hexadecimal representation of the provided number. *
iValue the number to represent in hexadecimal.
the hexadecimal representation of the provided number. */
public static String toHex(final int iValue) {
final String alpha = " ABCDEF"; // representing values
final int iRemainder = (iValue % 16); // amount left over
String strHex;
if (iValue == iRemainder) {
strHex = alpha.charAt(iRemainde);
} else {
strHex = toHex(iValue / 16) + alpha.charAt(iRemainder); }
return strHex;
} // toHex() 80 15 f f f 15

13. Encoding Examples Colour representation Red Green Blue (RGB) Purple
Three bytes one for each colour
Purple
D5F1C9
Examples
213 49
201
Black
000000
Absence of any colour
Red
FF0000
Just RED colour
Green
00FF00
Just GREEN colour
Blue
0000FF
Just BLUE colour
White
FFFFFF
WHITE
colour
Purple:

14. Encoding Examples (cont.)
American Standard Code for Information Interchange (ASCII)
Encoding of characters and some symbols
Just English alphabet
Extended ASCII provides some extra Latin characters, for example Spanish ñ character
Unicode Character Representations
To support other languages it is required 2 bytes - called internationalisation
Java uses Unicode Character Representation (16 bits representation)

15. Encoding
ASCII
DEC
HEX
BIN
Symbol
... 53 35 5 74 4A J 95 5F _ 33 21 ! 54 36 6 75 4B K 96 60 ` 34 22
" 55 37 7 76 4C L 97 61 a 23 # 56 38 8 77 4D M 98 62 b 24 $ 57 39 9 78 4E N 99 63 c 25 % 58 3A : 79 4F O
100 64 d 26
& 59 3B ; 80 50 P
101 65 e 27 ' 3C
< 81 51 Q
102 66 f 40 28 ( 3D = 82 52 R
103 67 g 41 29 ) 3E
> 83 S
104 68 h 42 2A * 3F ? 84 T
105 69 i 43 2B + @ 85 U
106 6A j 44 2C , A 86 V
107 6B k 45 2D - B 87 W
108 6C l 46 2E . C 88 X
109 6D m 47 2F / D 89 Y
110 6E n 48 30 E 90 5A Z
111 6F o 49 31 1 70 F 91 5B [
112 p 32 2 71 G 92 5C \
113 q 3 72 H 93 5D ]
114 r 4 73 I 94 5E ^ a A
A byte represent a character in ASCII but just in English alphabet, the extended ASCII cover other characters like Latin (Spanish).
Need to use 2 bytes to be able to represent all languages in the world.
Java has build-in support for internalisation.
/**
* Builds the binary representation of the provided number. *
iValue the number to represent in binary.
iBase the base of the encoding, form 2 (binary) to 16 (hexadecimal).
the binary representation of the provided number.
IllegalArgumentException when an invalid encoding base is provided. */
public static String toEncode(final int iValue, final int iBase) {
if (iBase < 2 || iBase > 16) {
// Runtime exception so does't need to be specified in the method declaration
throw new IllegalArgumentException("Invalid encoding base of " + iBase
+ " that should be bigger or equal to 2 and smaller or equal"
+ " to 16"); }
final String alpha = " ABCDEF"; // representing values
final int iRemainder = (iValue % iBase); // amount left over
String strRepresentation;
if (iValue == iRemainder) {
// Last element in the representation
strRepresentation = alpha.charAt(iRemainde);
} else {
// Build next element in the representation
strRepresentation = toHex((iValue/iBase), iBase) + alpha.charAt(iRemainder);
return strRepresentation;
} // toEncode()