JAVA METHODS A& AB

BEFORE WE BEGIN…

Return your Karel J. Robot book!

Go to: http://www.skylit.com/javamethods Click on “students” link under downloads

section Download the student disk to your student

drive

CHAPTER 1

Topics: - Hardware - Software and Programming overview - Computer Memory

CHAPTER 1

Students will: - be able to identify and explain hardware

components - explain the relationship between hardware,

software, and the internet - explain what a programmer does - will convert between numbering systems - learn the significance of ASCII code

HARDWARE

The most important piece: Central Processing Unit (CPU) - responsible for all mathematical

computations - 1995 processor -100 MegaHertz How many computations is that? Mega = 1 million 100 million per second Today’s computers – 4 GHz

HARDWARE

Memory – where information is stored

RAM – random access memory RAM is space for CPU to read

and write data RAM retrieves stored data from

Hard Disk, and writes to HD to save info More RAM means less # of times

to retrieve data, so your computer is faster!

HARDWARE

RAM cont’d: An address bus is the channel from CPU to

RAM – it sometimes can limit information processing!

- it’s random because any piece of data can be returned in a constant time, regardless of physical location

- not true for a magnetic discs (like a Hard Disk) or optical discs they rely on moving parts, and retrieval time will

depend on the location of the previous item found

Thus, the less we access it, the better!

HARDWARE

Hard Disk Memory stored on magnetic discs Discs are stacked on each other, and rotate

so that fixed “heads” can retrieve data Stores large amounts of data More RPM’s = faster retrieval

HARDWARE

I/O devices I/O is used to describe anything that has

input or output Input – keyboard, mouse, gamepad Output – monitor, speakers

HARDWARE

PC Board = printed circuit board - a.k.a. motherboard Brings it all together Holds CPU, memory, I/O devices Also holds CMOS

Holds basic instructions computer needs to initialize hardware and bootup

Does not require external power

SOFTWARE

The stuff that we write! It can be thought of as information recorded

on some medium Layers of software on a computer -BIOS, device drivers - Operating System - Software Applications

PROGRAMMERS

That’s us! 5 steps a programmer typically follows: 1. Defining the need 2. Designing a flowchart 3. Coding the software 4. Debugging 5. Beta testing

THE INTERNET

Simple version: Beginning – ARPANET, 1969 – connected 2

computers Today – internet relies on global T3 lines (~45

MB/sec transfer rate) to transmit data requests

Smaller “tributary” lines provide data locally Your IP (internet protocol) is unique to your

machine – you make a request, it travels along the route to the server where the website is hosted, then the information requested is returned to your IP

HOMEWORK Read Chapter 1 in book

Book will direct you online to finish chapter Writing Assignment Address the following 3 prompts:

1. Explain the relationship between hardware and software 2. Describe the origins of the internet, how it works, and

how it relates to your answer for #1 3. Explain what a programmer does, and give some varied

examples 4. Explain yours understanding of computer memory Min – 2 pages (dub space), Max – 3 pages 5. Create a visual diagram of a computer labeling all of the

components we took notes on (feel free to include components we didn’t talk about!) add to your writing assignment

Your book will be an excellent source for this assignment

MEMORY

How do computers represent information? Fundamental level – binary! CPU consist of transistors that have 2 states: 0 – low voltage state 1- high voltage state Bit – one binary digit Byte – eight bits 1 byte has 256 different possibilities (2^8 =

256)

MEMORY How many combinations will 2 bits have? 00, 01, 10, 11 – 22

= 4 combinations Reading binary: From right to left, each digit is 2^place

holder, starting with 0 Ex) 0001 is 2^0 =1, 0010 is 2^1=2 Q: What is 1101 in decimal?

NUMBER SYSTEMS

Programmers find it useful to be able to quickly convert between decimal and binary

1 way:Example 1 - (Convert Decimal 44 to Binary) subtract the largest power of two, and count that number as a 1

NUMBER SYSTEMS Easier method for large

decimal numbers: Division by 2: Take a decimal number, and

do long division by your base (in this case, base 2 for binary)

Keep track of remainders… divide until the quotient is 1

Read from bottom to top for binary answer

Example: 156 to binary

Keep remainders to right..

2)156 02)78 02)39 12)19 12)9 12)4 02)2 0 1

156 = 10011100

NUMBERING SYSTEMS Try to convert the following 001011101010110100101001010110010100

10 That is a bit too difficult – instead of trying to

read that, programmers typically use a base 16 system, hexadecimal (groups of 4 binary numbers: 2^4 = 16)

0123456789ABCDEF are the 16 hex digits Why not just use the decimal system? It is not a derived from a base 2 system

NUMBERING SYSTEMS It is recommended to know these: Decimal Hexadecimal Binary 0 0 0000 1 1 0001 2 2 0010 3 3 0011 4 4 0100 5 5 0101 6 6 0110 7 7 0111 8 8 1000 9 9 1001 10 A 1010 11 B 1011 12 C 1100 13 D 1101 14 E 1110 15 F 1111

NUMBERING SYSTEMS

It is better to know how to convert: Use remainder system to convert from

decimal to hex (ex 1243): 1243 / 16 = 77, remainder 11 (B) 77 / 16 = 4, remainder 13 (D) 4 / 16 = 0, remainder 4 1243 = 4DB in hexadecimal (or 04DB)

NUMBERING SYSTEMS Convert hex to decimal: try the Hex 11A3 Start from right to left… multiply each by

16^ place value So 3 * 16^0 = 3 A(10) * 16^1 = 160 1 * 16^2 = 256 1 * 16^3 = 4096 Answer: 4096+256+160+3 = 4515

NUMBER SYSTEMS

From binary to hex Break binary into chunks of 4: Ex) 101011 = 0010 1011 Convert chunks into decimal 0010 1011 = 2 11 = 2 B From hex to Binary – do the opposite 4A2F = 4 10 2 15 = 0100 1010 0010 1111

NUMBER SYSTEMS Practice: Convert the following to both decimal and

hexadecimal: 10000011, 10010011, 10111011 

Convert the following Hex’s to both decimal and binary: 34, 5A, CAB

HOMEWORK

Numbering System Conversion Worksheet Ch 1 Exercises - #1, 2, 5, 11, 12, 13, 14 Create a program that converts:

From decimal to binary From decimal to hexadecimal From binary to hexadecimal (the reverse of all of these)You can potentially write one method that takes a

base number as a parameter Worksheet due Tuesday; Exercises and

program due Wednesday before class ends