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Java Methods A& AB

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

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Java Methods A& AB

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  1. Java Methods A& AB

  2. 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

  3. Chapter 1 • Topics: • - Hardware • - Software and Programming overview • - Computer Memory

  4. 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

  5. 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

  6. 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!

  7. 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!

  8. 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

  9. Hardware • I/O devices • I/O is used to describe anything that has input or output • Input – keyboard, mouse, gamepad • Output – monitor, speakers

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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)

  16. 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?

  17. 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

  18. Number Systems 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 • 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

  19. 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

  20. 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

  21. 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)

  22. 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

  23. 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

  24. 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

  25. 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

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