Dec1999 SD206 : Systems Design (Question4)Suggested Solutions

(a)	(i)What are classification codes ?[2 marks ] Classification codes place separate entities,such as events,people,or objects, into distinct groups called classes (1 mark).A code is used to distinguish one class from another (1 mark). Other valid answers should also receive credit. (ii)Give one example ofthe application of a classification code.[1 mark ] One mark should be awarded for any suitable example. (iii)How do classification codes simplify the input process?[1 mark ] Classification codes simplify the input process as only one-or two-digit codes are required;the need for writing lengthy descriptions is reduced. Other valid answers should also receive credit.	[4]
(b)	(i)What are function codes ?[2 marks ] Codes are often necessary for instructing the system or decision maker which action to take next (1 mark).Function codes state the activities to be performed without spelling out the details of the activities (1 mark). Other valid answers should also receive credit. (ii)Give one example of the application ofa function code.[1 mark ] One mark should be awarded for any suitable example.	[3]
(c)	Name two circumstances in which cipher codes might be useful. One mark should be awarded for each valid point (up to a maximum of two marks). Examples include the following: •A corporation may not want information in a personnel file to be accessed by data-entry workers. •A store may want its sales people to know the wholesale price to indicate how low a price they can negotiate to,but it may be encoded on a price tag to prevent customers from seeing it. •A restaurant may want to capture information about the service customers receive,without the customers finding out the name ofthe waiter or waitress. Other valid answers should also receive credit.	[2]
(d)	(i)List two types of error which can be detected by use of a check digit. [2 marks ] Single digit miskeys (1 mark)and transposition errors (1 mark). (ii)What is the check digit of 30424 with a modulus of 10 and a 2-1-2 weighting method?[1 mark ] 6 (iii)What is the check digit of 30424 with a modulus of 10 and a 3-1-3 weighting method?[1 mark ] 5 (iv)What is the check digit of 30424 with a modulus of 11 and a 2-1-2 weighting method?[1 mark ] 9 (v)What is the check digit of 30424 with a modulus of 11 and a 3-1-3 weighting method?[1 mark ] 9	[6]