December 1998
SW204: SOFTWARE AND FILES DESIGN

QUESTION 4

Total Marks: 20 Marks

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SUGGESTED SOLUTIONS
for Question 4
4. (a) List three factors which you would take into account when choosing a type of file organisation.

 

 [3]
(b) For each of the following types of file organisation list two advantages:
(i) Sequential [2]
(ii) Indexed sequential [2]
(iii) Random

 

 [2]
(c) For each of the following types of file organisation list one disadvantage:
(i) Sequential [1]
(ii) Indexed sequential [1]
(iii) Random

 

 [1]
(d) Describe how a file checker detects inconsistency.

 

 [2]

(e) Given the following state of a file, list the blocks which are inconsistent and, for each inconsistent block, name the type of inconsistency.

 

Block number

0

1

2

3

4

5

6

7

8

9

10

11

12

13

In Use

1

0

1

0

0

1

2

1

1

0

1

0

0

0

Free

0

0

0

1

1

0

0

0

0

1

0

1

2

1

 

 [3]
(f) For each of the errors mentioned in Part (b), describe how the file checker might rectify the inconsistency. [3]