1,3 Data: Its Reprsentation, Structure And Management

Question 0

What is a character set?

Answer 0

This the complete set of characters that the computer uses

• Generally each character takes up one byte and this is the number of bits used to store it. Each character has its own binary value, which is the code by which the computer recognises it
• However in this system, any document created in one computer will not make sense as the code is interpreted differently. Therefore a standard set of code must be used. Unicode is an example, uses 16 bit code that uses 2 bytes, this makes it possible to represent ver 65,000 characters

Question 1

What is a byte?

Answer 1

This is a group of binary digits (often 8).

Question 2

What are the data types?

Answer 2

Numeric data
Boolean data
Character data 
String data 
Date/time data
Currency

Question 3

What is numerical data?

Answer 3

There are 3 data types for numbers
-Short integer takes up 2 bytes, who’s value has a limited range

• A byte can be used but it isn’t a standardised data type, it can be used for any value within the range of 0-99
• Long integer takes up 4 bytes an can have a value with a range that is much wider than that of a short integer

Question 4

What is Boolean data?

Answer 4

This is data which can have 2 states. The computer uses binary data which consists of bits of information that can have the value of either 0 or 1

-A variable of this data type would hold 2 bytes

Question 5

What is character data?

Answer 5

A character is anything that is represented in the character set of the computer. Usually stored as a single byte

Question 6

What is the binary sequence?

Answer 6

It is usually:

128,64,32,15,8,4,2,1

Question 7

What is an array?

Answer 7

This is a group of variables stored together, with the same identifier name

Question 8

What is the program for a serial search into an array?

Answer 8

While index t run over 10 times

-This program is supposed to find out the index number of an item of data that the user is looking for

Question 9

What is a queue?

Answer 9

This is a method of processing data which consists of a start pointer and end pointer

• The start pointer identifies which jobs needs to be done next
• The end pointer indicates where the next job can go
• In this method, the first job in is the first job to be processed. FIFO

Question 10

What is a stack?

Answer 10

This is a method of processing data which consist of an end pointer only

-This means that jobs are done at the same place as they are added, LIFO

Question 11

What are the different methods of accessing data?

Answer 11

Serial access
Sequential access
Indexed access
Random access

Question 12

What are the different methods of organising files?

Answer 12

Serial organisation
Sequential organisation
Random organisation

Question 13

What is serial organisation?

Answer 13

This is when records are entered in the order of their creation, they are in chronological order

Question 14

What is sequential organisation?

Answer 14

This is when are ordered in a logical sequence according to a field key. These records are sorted based on key values

Question 15

What is random organisation?

Answer 15

This is when the records are in a random order, and though there is no sequencing not the placement of the records, there is a predefined relationship between the key of the record and it’s location within the file.

Question 16

What is serial access?

Answer 16

This is accessing an unordered file and reading into it from start to finish

Question 17

What is sequential access?

Answer 17

This is reading