This paper is not to be removed from the Examination Halls UNIVERSITY OF LONDON

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1 ~~IS1168 ZA d0 This paper is not to be removed from the Examination Halls UNIVERSITY OF LONDON IS1168 ZA BSc degrees and Diplomas for Graduates in Economics, Management, Finance and the Social Sciences, the Diplomas in Economics and Social Sciences and Access Route Introduction to Computer Systems Architecture and Programming Thursday, 02 May 2013 : 2.30pm to 5.30pm Candidates should answer FOUR of the following EIGHT questions: TWO from Section A and TWO from Section B. All questions carry equal marks. PLEASE TURN OVER UL13/0226 Page 1 of 6

2 SECTION A Answer two questions from this section. 1. In the mid 1940s John von Neumann played a key role in the development of the EDVAC (Electronic Discrete Variable Automatic Computer). In developing the EDVAC Von Neumann explored the ideas of an architecture that today is still referred to as the von Neumann architecture. With the help of a graphical representation explain the underlying ideas and components of this architecture. Why did Von Neumann suggest this architecture? (12 marks) Although the von Neumann architecture became the basis for most computers, the architecture has some drawbacks. Describe a major drawback and suggest how it may be addressed. (4 marks) The EDVAC is also considered to be the first binary (rather than decimal) computer. i. With the help of an example explain what this means. (3 marks) ii. Explain the main reasoning behind the move from decimal to binary. (6 marks) UL13/0226 Page 2 of 6

3 2. Computers are constructed using logic gates. Explain the underlying ideas of Boolean logic and give examples of the main Boolean operations and their associated truth tables. Explain how different gates use the ideas of Boolean logic. (5 marks) The circuit below is generally referred to as a multiplexer (or data selector). With a multiplexer it is possible to select one of several input signals and forward the selected input to a single output line. i. Create the truth table for the multiplexer below. ii. Explain how selection is carried out in this multiplexer. Can you suggest where this type of circuit may be useful? UL13/0226 Page 3 of 6

4 3. The scheduling and coordination of program execution is one of the main tasks of a computer s operating system. Explain how the scheduler and the dispatcher support these operating system tasks. Semaphores are said to help control the access of multiple processes to one or more common resources. Explain what a semaphore is and, with the help of an example, explain how a semaphore can avoid scheduling problems. How does a semaphore deal with more than one resource of the same type? (12 marks) Within a computer system several processes have to make use of the same printer. Suggest an appropriate scheduling method for this scenario and justify your choice. (3 marks) 4. The World Wide Web (WWW) can be described as an internet-based hypermedia enterprise that facilitates global information sharing. With the help of an illustration, follow the layers of the TCP/IP Model and explain how network software would coordinate and control a simple request for a web page. Your illustration should include the client machine (with a browser) and the Web server. You should also identify and explain relevant protocols. (15 marks) The Semantic Web has been said to be an extension of the current WWW. Explain what the Sematic Web is. Show how XML (Extensible Markup Language) can support the implementation of the Semantic Web by showing how it may be used to represent the entries in a CD music catalogue. UL13/0226 Page 4 of 6

5 SECTION B Answer two questions from this section. 5. It has been argued that a main reason for Java s popularity is the fact that the language is objectoriented. Explain the underlying ideas of object-orientation and, with the help of examples, explain how Java uses the concept of a class to realize these ideas. (15 marks) Wrapper classes can be used whenever there is a need for object representations of primitive data types. Give an example of when it may be useful to represent a primitive data type as an object and, with the help of an example, explain how a wrapper class can facilitate this. 6. Java allows you to create your own classes. You have been asked to create a class for a Rectangle Object. List the attributes and methods that may be relevant to the Rectangle Class. (4 marks) Create a Rectangle Class in Java. Objects of your class should be able to work out their surface area. Include comments that clearly identify and explain constructors, instance variables, methods and any other relevant information. (9 marks) Create a program that calculates the surface area for 2 rectangles (choose your own dimensions) and then displays the area and the dimensions (height and width) of the bigger rectangle. Ensure you include comments to explain your coding. (12 marks) 7. The if statement is used to change the sequential flow of control throughout a program. With the help of examples, explain the terms Boolean expression and relational expression. (6 marks) Explain how Boolean expressions may be used within the if statement to change the flow of control within a program. Use an example to support your explanation. (4 marks) Repetition can be implemented using the while loop. Demonstrate how the while loop works by writing a small, well-documented program that displays a square pattern of circles (use the letter "o") on the screen. Your program should ask the user for the size of the square. For example, if a user enters 3 the program should display: ooo ooo ooo (15 marks) UL13/0226 Page 5 of 6

6 8. An array is a data structure that allows you to store a fixed number of data elements of the same data type. Although arrays allow for organised and convenient storage of elements of the same data type, there are some disadvantages associated with the use of arrays. Outline two. (4 marks) You have been asked to write a program that helps a teacher with the recording of exam results for the students in his/her class. Your program should use an array and - read in the student ID of 50 students. (The student ID is an 8 digit number.) - record the marks for each student for 7 different subjects. - determine the top mark achieved in each of the 7 subjects. You must use comments throughout your program code to explain how your program works. (21 marks) END OF PAPER UL13/0226 Page 6 of 6