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Cork Institute of Technology
Higher Certificate in Science in Computing in Information
Technology Support – Stage 1
(NFQ Level 6)
Autumn 2006
Computer Systems
(Time: 2 Hours)
Examiners: Mr. S. Lankford Answer FOUR questions.. All questions carry equal marks.
Mr. A. O’Brien Mr. P. O’Connor Mr. J. Greenslade Mr. J. Walsh
Q1. a) Describe the function of the following in the 68000 microprocessor: i) PC ii) IR iii) SR iv) ALU [8 marks] b) The design / pseudo code for a simple program is written below. Write the corresponding program in 68000 assembly language. D0 = 1 D1 = 7 D2 = 4 WHILE ( D0 != D1 ) { D0 = D0+1; IF ( D0 >= 5 ) { D2 = D2 - 1 } } [6 marks]
c) Draw the truth tables and circuits for the following: i) A Half Adder [3 marks] ii) Full Adder [3 marks] d) Using a black box design for a full adder, design a simple circuit to implement a 4-bit ripple carry adder [5 marks] (Total: 25 marks)
Q2 a) Convert the following from decimal (base 10) to binary (base 2). Show your calculations. 112 10 [5 marks]
b) i) Convert the following from Binary to Hexadecimal 11100101010010112 [2 marks] ii) Convert the following from Hexadecimal to Binary BACE 16 [2 marks]
c) Convert the following number to Floating Point Format: 5.0625 [8 marks] _ _ d) Draw the circuit and the truth table for the expression: (X +Y)(X + Z) [8 marks]
(Total: 25 marks) Q3. a) What is the function of IRQs in computer systems? [3 marks]
b) Define what is meant by a COM port and an LPT port? How do they differ and where would they be configured in a Windows operating system? [8 marks]
c) A technician adds two expansion cards to his system: a network card and a sound card. The sound card uses I/O addresses 300 – 330 and IRQ5. The network card uses I/O addresses 310 – 340 and IRQ2? When the system is booted up, what will happen? [4 marks]
d) Briefly describe the different types of adapters, which may be found on the Expansion bus? In your description, discuss both the modern and old types of adapters [10 marks]
(Total: 25 marks)
Q5.
a) Briefly explain what is meant by the term “Access Time” in the context of a hard disk? [2 marks]
b) Briefly describe the operation of a typical hard disk outlining how the various components of the disk operate. Illustrate the internal structure of such a hard disk. [10 marks]
c) Briefly describe the operation of a floppy disk. In your description, explain the following: i. Typical rotational speed ii. Boot Sector iii. FAT [7 marks]
d) Examine the following section of a FAT, which has a starting cluster of 221, and determine:
i. How many sectors are in the file? ii. The sequence of sectors that make up the file iii. What is the last sector in the file?
FAT Contents 97 224 1258 226 222
FAT Index 220 221 222 223 224 225 226
[6 marks]
(Total: 25 marks)
Q6.
a) What are the typical components found on a modern motherboard? [7 marks]
b) What does BIOS stand for and what is its function at system startup i.e. what tasks does it perform? [6 marks]
c) Briefly explain what is meant by the term motherboard form factor and what are the most common motherboard form factors today? [4 marks]
d) Briefly, describe what is meant by the chipset of a motherboard and outline the functions of the Southbridge and Northbridge? Using a simple block diagram, illustrate how the chipset components on the motherboard. In your diagram, label all the important components. [8 marks]
(Total: 25 marks) Appendix 1 Frequently used Branch instructions: Branch Condition Flag Setting BEQ EQUAL Z= BNE NOT EQUAL Z= BGT GREATER Z+(N XOR V) = BLT LESS N XOR V = BGE GREATER OR EQUAL N XOR V = BLE LESS OR EQUAL Z +(N XORV) =
