JAVA METHODS A& AB
BEFORE WE BEGIN…
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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
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CHAPTER 1
Topics:
 - Hardware
 - Software and Programming overview
 - Computer Memory
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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
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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
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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
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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
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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!
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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
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HARDWARE
I/O devices
 I/O is used to describe anything that has input or
output
 Input – keyboard, mouse, gamepad
 Output – monitor, speakers
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HARDWARE
PC Board = printed circuit board
 - a.k.a. motherboard
 Brings it all together
 Holds CPU, memory, I/O devices
 Also holds CMOS
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Holds basic instructions computer needs to initialize
hardware and bootup
 Does not require external power
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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
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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
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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
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HOMEWORK
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Read Chapter 1 in book
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Book will direct you online to finish chapter
Writing Assignment
Address the following 3 prompts:
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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)
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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?
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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
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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
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Example: 156 to binary
 Keep remainders to
right..
2)156 0
2)78 0
2)39 1
2)19 1
2)9 1
2)4 0
2)2 0
1
156 = 10011100
NUMBERING SYSTEMS
Try to convert the following
 00101110101011010010100101011001010010
 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
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NUMBERING SYSTEMS
 It
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is recommended to know these:
Decimal
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Hexadecimal
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Binary
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)
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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
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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
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NUMBER SYSTEMS
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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:
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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
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