S4 ICT Paper: Hardware And Storage Units, Binary And Hexadecimal Numbers, Operating Systems, Spreadsheets, Programming And Network Security

S4 ICT Paper: Hardware and Storage Units, Binary and Hexadecimal Numbers, Operating Systems, Spreadsheets, Programming and Network Security

2026-11-13

S4 ICT – computer systems and programming

S4 ICT paper: 6 questions, 100 marks on hardware and storage units, binary, hex, character encoding, operating systems, spreadsheets, loops and network security.

Download　Question paper PDF　|　Answer key PDF

Paper details　S4 ICT practice paper: 6 questions with answers on hardware and storage units, binary and hex numbers, character encoding, operating systems, spreadsheets, loops and network security.

Section A: Computer Hardware and Storage Units (16 marks)

A computer has 16 GB of RAM and a 2 TB hard disk. 1 GB = 1024 MB and 1 TB = 1024 GB. A photograph is 4.5 MB in size, and a 3-minute video has a bit rate of 8 Mbps.

#	Question	Answer and marking notes
1	Convert the memory capacity to MB and state the value.	Answer: 16 x 1024 = 16384 MB. (Marking: conversion factor 2, correct value 2)
2	Estimate the maximum number of photographs the hard disk can hold, as a whole number.	Answer: capacity = 2 x 1024 x 1024 = 2097152 MB; photographs = 2097152 / 4.5 = 466033 (rounded down). (Marking: capacity 2, division 1, rounding 1)
3	Find the file size of the video in MB.	Answer: data = 8 x 180 = 1440 Mb; size = 1440 / 8 = 180 MB. (Marking: bit and byte conversion 2, answer 2)
4	State two main differences between RAM and ROM.	Answer: (1) RAM is readable and writable while ROM is normally read-only; (2) RAM loses its contents when power is removed while ROM keeps them; (3) RAM holds running programs and data while ROM holds start-up instructions and firmware. (Marking: 2 marks per difference, two required)

Section B: Binary, Hexadecimal and Character Encoding (18 marks)

An 8-bit register stores the value 182. The system also uses 8-bit two-s complement to represent signed integers.

#	Question	Answer and marking notes
5	Write 182 as an 8-bit binary number.	Answer: 182 = 128 + 32 + 16 + 4 + 2 = 10110110. (Marking: place values 2, 8-bit form 2)
6	Write the same binary number in hexadecimal and check its value.	Answer: split 10110110 into 1011 and 0110, giving B6, value = 182, which matches 182. (Marking: grouping 2, hexadecimal answer 2)
7	Represent -45 in 8-bit two-s complement, showing the method and the result.	Answer: 45 = 00101101; invert every bit to get 11010010; add 1 to get 11010011, which is -45. (Marking: positive binary 2, inversion 2, add one and answer 1)
8	Explain the difference between ASCII and Unicode, and why Chinese documents need Unicode.	Answer: ASCII uses 7 bits for 128 characters and covers only English letters, digits and basic symbols. Unicode encodes characters of all languages with several bytes and covers tens of thousands of Chinese characters. Chinese has far more than 128 characters, so ASCII cannot represent it and Unicode is required. (Marking: ASCII range 2, Unicode range 2, reason for Chinese 1)

Section C: Operating Systems, File Transfer and Cloud Storage (17 marks)

A 250 MB file is uploaded to the cloud over a 20 Mbps link, and 1 MB = 8 Mb. The transfer is interrupted and 40% of the data must be sent again.

#	Question	Answer and marking notes
9	Find the time needed for the first upload in seconds.	Answer: data = 250 x 8 = 2000 Mb; time = 2000 / 20 = 100 s. (Marking: MB to Mb 2, division and answer 2)
10	Find the total upload time including the resend, in seconds.	Answer: resending 40 percent takes 100 x 0.4 = 40 s; total time = 100 + 40 = 140 s. (Marking: resend time 2, total time 2)
11	List three main functions of an operating system and give one example of each.	Answer: (1) memory management, for example allocating memory to running programs; (2) file management, for example creating, deleting and moving files; (3) input and output device management, for example driving a printer through a device driver. (Marking: 2 marks per function with example, three required)
12	Compare cloud storage with a local hard disk and give one advantage of each.	Answer: cloud storage can be reached from any place with a network and is backed up automatically; a local disk needs no network, works faster and keeps the data under the owner control. (Marking: cloud advantage 2, local advantage 2)

Section D: Spreadsheets and Formulas (17 marks)

In a spreadsheet A1 holds 120 (quantity), B1 holds 15 (unit price) and C1 holds the formula =A1*B1. D1 holds a conditional formula that takes 90 percent of C1 when C1 is greater than 1000, otherwise C1. E1 to E4 hold 12, 18, 25 and 45.

#	Question	Answer and marking notes
13	Find the value shown in C1.	Answer: C1 = 120 x 15 = 1800. (Marking: formula 2, value 2)
14	Find the value shown in D1 and explain why.	Answer: C1 = 1800 is greater than 1000, so the condition is true and D1 = 1800 x 0.9 = 1620. (Marking: test condition 2, calculation 1, explanation 1)
15	Write the formula that finds the average of E1 to E4, and state the answer.	Answer: the formula is =AVERAGE(E1:E4); the sum is 100 and the average is 100 / 4 = 25. (Marking: function and range 2, answer 2)
16	Explain the difference between absolute and relative references, and give an example of when an absolute reference is needed.	Answer: a relative reference such as A1 shifts its row and column when the formula is copied; an absolute reference such as $A$1 is fixed with dollar signs. An absolute reference is needed when every copied formula must multiply by the same fixed cell, for example a fixed tax rate, otherwise the reference drifts and the results become wrong. (Marking: relative 2, absolute 2, example and consequence 1)

Section E: Programming Basics (16 marks)

Program A: total = 0; for i from 1 to 5 repeat total = total + i. Program B: n = 1; while n is less than 20 repeat n = n * 2.

#	Question	Answer and marking notes
17	Trace program A and state the final value of total.	Answer: 1 + 2 + 3 + 4 + 5 = 15. (Marking: cumulative addition 3, answer 1)
18	How many times does the loop body of program B run? State the value of n in each round.	Answer: the loop body runs 5 times; n becomes 2, 4, 8, 16, 32 in turn, then n = 32 is no longer less than 20 and the loop stops. (Marking: count 2, values 2)
19	Explain the difference between a syntax error and a logic error, giving one example of each.	Answer: a syntax error breaks the rules of the language so the program cannot be compiled or run, for example a missing closing bracket or a misspelled keyword. A logic error still runs but gives a wrong result, for example writing a subtraction instead of a sum, or setting a wrong loop end condition. (Marking: syntax error with example 2, logic error with example 2)
20	Write pseudocode that finds the largest value in an array.	Answer: max = arr[0]; for each element x compare in turn: if x is greater than max then max = x; finally output max. The loop makes n – 1 comparisons, so the time complexity is O(n). (Marking: initial value 1, loop and comparison 2, output 1)

Section F: Network Security and Information Literacy (16 marks)

A login accepts either a 4-digit PIN or an 8-character password. The characters allowed are 26 uppercase letters, 26 lowercase letters and 10 digits, and characters may repeat.

#	Question	Answer and marking notes
21	Find the total number of 4-digit PINs.	Answer: each digit has 10 choices, so there are 10 to the power 4 = 10000 combinations. (Marking: choices per digit 2, answer 2)
22	Find the total number of 8-character passwords, in scientific notation to three significant figures.	Answer: there are 26 + 26 + 10 = 62 possible characters; combinations = 62 to the power 8 = 2.18e+14. (Marking: character count 1, power 2, notation 1)
23	Explain the role of a firewall and of encryption in protecting data on a network.	Answer: a firewall filters packets entering and leaving the network according to rules and blocks unauthorised connections and ports; encryption turns data into ciphertext so that an interceptor without the key cannot read the contents. (Marking: firewall 2, encryption 2)
24	A student copies an article found online directly into homework. State two problems with this, one about copyright and one about academic honesty.	Answer: on copyright, the article is someone else work and copying or publishing it without permission may infringe copyright; on academic honesty, using it without a citation is plagiarism, so the teacher cannot judge the student own ability, which is a serious offence. (Marking: copyright 2, academic honesty 2)

Find a tutor — free Tutor Registration →

A TutorZone practice paper; original questions and passages, not publisher material.