IFT 201 HW3

Lab 3: Character Encoding

Score: 60pts

Introduction

As discussed, every kinds of data in a computer must be represented by a sequence of 1s and 0s (binary system). The manner in which these electronic data are converted to a form meaningful to humans depend on the coding system used by the computer.

So the myriad data forms have to be represented using only 1s and 0s; including text, numbers, sounds, colors, still pictures, moving pictures, etc.

· How are characters represented?

A character “mapping” assigns a number to each character, and then this assigned number is encoded in binary. For example, a very simple mapping scheme might assign 1 to A, 2 to B, etc. A computer would then store B as 10, the binary representation of 2.

· Which mapping to use?

It took a long time for the computer industry to stop using many different mappings:

· IBM mainframes used EBCDIC,

· Control Data Corporation (CDC) supercomputers used their own system

· Digital Equipment Corporation (DEC) and other smaller companies used ASCII.

The breakthrough coincided with the introduction of PC in 1981, which used ASCII even though it was an IBM.

ASCII has grown ever since to become practically one of the only two character mappings used today (the other being Unicode).

Background

Read the ASCII character set and text representation from any of the following sources:

· Hand-outs, section 2.6

· Online resources

Download and extract the provided programs:

· ASCII Converter v3.1: ASCIIv3_1.zip

· Text to Binary converter: btt_0.3.zip

· If you don’t have a Windows system, you’ll need to use virtual box with a Windows VM

The ASCII converter can convert plain text to hex and back using the standard ASCII character set. For example, type E0 in the “Hexadecimal” area and click on “Convert”, you’ll see à in the “Plain Text” area.

The Text to Binary converter program makes it easy to type in some text and have the computer translate all of it to binary using the ASCII character mapping. The (binary) output is a string of binary numbers separated by spaces, each representing an ASCII value. The screenshot below provides an example.

Note that inside the computer’s memory, there are no spaces between the seven-bit chunks that represent each character.

Most computers today store one ASCII character in a byte, which is 8 bits, not 7. The ASCII character set was extended to include 128 extra characters, many of them for PC graphics.

Activities

For these activities, you can use any or a combination of the two programs.

1. Convert decimal 100 to hex: ________________

Type the hex representation into the bottom area of the ASCII Converter program

Write down what you see: ______________

2. Do the same for 68

68 = ________ hex

ASCII __________

3. What relation do the above two numbers have?

4. Do as in 1) for

a) 101 and 69

b) 102 and 70

Write down the codes and the characters you see

5. What conclusion can you draw about how upper- and lowercase characters in ASCII are represented, based on your experiments?

6. If you were writing a function to capitalize text for a word-processing program, what simple transformation would you make to the character codes to capitalize a letter?

7. What does ASCII code 241 look like? What language uses this character?

Provide a screenshot

8. We’ll now see how the computer stores your ASU username.

Write down its binary conversion. Also provide a screenshot

Provide its decimal representation.

9. Provide the decimal representation for each of the following characters: ç, é, $, £

Be sure to provide the screenshot of your initial step

Deliverables

Editing

Prepare your deliverable using this lab document as followed:

1. Answer all the questions in the “Activities” section, illustrating your work with screenshot whenever applicable.

Submission

1. Save your file as lab3_<YOUR USERNAME>.docx. Replace <YOUR USERNAME> with your ASURITE username. If you’re not using MS Word (for example, if you’re using Mac), please submit a PDF document.

2. Be sure to include your full name on every page. You can insert it in the header, on above the “IFT 201” banner.

3. Upload your file to Blackboard.

 

Do you need a similar assignment done for you from scratch? Order now!
Use Discount Code "Newclient" for a 15% Discount!