MSHS 2019 P1 Solution

Class Index Number Name MARIS STELLA HIGH SCHOOL PRELIMINARY EXAMINATION SECONDARY FOUR COMPUTING 7155/01 Paper 1 Written 28 Aug 2019 2 hours Candidates answer on the Question Paper. No Additional Materials are required. MARK SCHEME For Examiner’s Use This document consists of 13 printed pages. 80

2 1 Insert six of the following words or numbers about computers and data in the correct place in the text below. 2 10 16 analogue binary denary digital hexadecimal While analogue data is transmitted via fibre optical cables, a computer cannot process this type of data. For a computer to be able to process data, it needs to be converted to digital data. As humans, we mostly use a denary number system; this is a base 10 number system. Computers use a binary number system; this is a base 2 number system. [6] 2 The three binary numbers in the registers X, Y, Z were transmitted from one computer to another. Parity bit Register X 1 0 0 1 1 0 0 0 Register Y 0 1 1 0 0 1 1 1 Register Z 1 0 0 1 1 0 0 1 One binary number was transmitted incorrectly. This is identified through the use of a parity bit. Identify which register contains the binary number that was transmitted incorrectly. Explain the reasons for your choice. Any three from: - Count the number of 1/0 bits (in each byte/register) - Two bytes/registers have an odd number of 1/0 bits // Two use odd parity - Odd parity must be the parity used - One byte/register has an even number of 1/0 bits // One uses even parity - One with an even number of one bits/even parity is incorrect// Register Z should be odd parity [4] 3 John is writing a program using a high-level language. The program will be published and sold for a profit.

3 (a) John uses an interpreter when creating the computer program. State three features of an interpreter. [3] (b) James writes a similar code and compiled the program when he completed it. Explain two benefits of compiling the program. [4] (a) Any three from: - Executes one line at a time // translates source code line by line - Produces error message to tell user location of error // easier to debug code - Stops execution once the program encounters an errors - Changes to the source code take effect immediately - Interpreters usually offer an interactive mode, which facilitates learning and experimentation. (b) Any four from: - Produce executable file… - … more saleable - Program will be machine independent/portable… - … this means it can be used on any hardware - No need for compiler to run executable file… - … this means it will be quicker to run - … customers can just execute the program - Source code cannot be accessed… - … therefore, code cannot be stolen/plagiarised