Computer Systems: Chapter 1 (Data Representation)

Question 1

What is floating point notation?

Answer 1

When you store a number as a floating point number with a mantissa and an exponent

Question 2

What is a mantissa? What happens when you increase the mantissa?

Answer 2

• The mantissa holds the number in decimal form

* When you increase the mantissa, you increase the precision of the numbers being stored

Question 3

What is an exponent? What happens when you increase the exponent?

Answer 3

• The exponent holds the power of the number

* When you increase the exponent, you increase the range of numbers being stored

Question 4

What is American Standard Code for Information Interchange (ASCII)?

Answer 4

ASCII is a 7 bit code that stores text as integer values in it

Question 5

What is UNICODE?

Answer 5

UNICODE is a 16 bit code that stores all ASCII values in its first 256 characters

Question 6

What is an advantage of UNICODE over ASCII?

Answer 6

It contains every character based alphabet in the world including graphical languages like Chinese

Question 7

What is a bit-mapped graphic?

Answer 7

It is a graphic that is made up of a grid of pixels, and a unique binary number represent each colour in the graphic

Question 8

What is a vector graphic?

Answer 8

It is a graphic that is made up of layers of shapes with attributes describing them

Question 9

What are the advantages of bit-mapped graphics? (2)

Answer 9

• They allow you to edit at pixel level

* Storing a bit-mapped graphic will be the same size no matter how complex the graphic

Question 10

What are the disadvantages of bit-mapped graphics? (2)

Answer 10

• They require a lot of storage space

* When you re size the graphic it becomes pixilated and blocky

Question 11

What are the advantages of vector graphics? (2)

Answer 11

• You can edit individual objects

* When you resize a vector graphic, the edges stay smooth and do not become pixilated

Question 12

What are the disadvantages of vector graphics? (2)

Answer 12

• You can’t edit at pixel level

* Storing complex vector graphics requires a lot of storage space

Question 13

What is bit depth?

Answer 13

Bit depth is the number of bits used to represent a pixel in bit-mapped graphics

Question 14

What is true colour?

Answer 14

True colour is represented on a computer system using 24 bits per pixel, giving 2^24 possible colours

Question 15

What is compression?

Answer 15

Compression means reducing the file size of a graphic in order to save backing storage space

Question 16

What are the 2 types of compression used in graphic files?

Answer 16

• Lossy compression, which sacrifices some of the data in order to reduce the file size (.jpg)
• Lossless compression, which means that none of the original data is lost (.png) (.gif)

Question 17

What is the difference between bit-map resolution and vector resolution?

Answer 17

Bit-map resolution is fixed, and vector resolution is independent

Question 18

What is resolution independance?

Answer 18

When a picture is created using a vector graphics package, the resolution of the screen has no effect on the resolution of the printout