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Types of Memory

Candidates should be able to: describe the difference between RAM and ROM explain the need for ROM in a computer system describe the purpose of RAM in a computer system explain how the amount of RAM in a personal computer affects the performance of the computer explain the need for virtual memory describe cache memory …

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The Central Processing Unit (CPU)

Candidates should be able to: state the purpose of the CPU describe the function of the CPU as fetching and executing instructions stored in memory explain how common characteristics of CPUs such as clock speed, cache size and number of cores affect their performance. What is the purpose and function of the CPU? The purpose …

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Number Systems

For Number Systems, candidates should be able to: convert positive denary whole numbers (0-255) into 8-bit binary numbers and vice versa add two 8-bit binary integers and explain overflow errors which may occur convert positive denary whole numbers (0-255) into 2-digit hexadecimal numbers and vice versa convert between binary and hexadecimal equivalents of the same …

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Data Units

For Data Units, candidates should be able to: define the terms bit, nibble, byte, kilobyte, megabyte, gigabyte, terabyte understand that data needs to be converted into a binary format to be processed by a computer. Data units in computer systems Bit This is a single unit of memory and can only store 2 possible binary …

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Image Representation

For Image Representation, candidates should be able to: explain the representation of an image as a series of pixels represented in binary explain the need for metadata to be included in the file such as height, width and colour depth discuss the effect of colour depth and resolution on the size of an image file. …

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Sound Representation

For Sound Representation, candidates should be able to: explain how sound can be sampled and stored in digital form explain how sampling intervals and other considerations affect the size of a sound file and the quality of its playback. How can sound be sampled and stored in digital form? A microphone converts sound waves into …

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DBMS

Candidates should be able to: describe how a DBMS allows the separation of data from applications and why this is desirable describe the principal features of a DBMS and how they can be used to create customised data handling applications. What is a DBMS? A Database Management System (DBMS) is used to manage a database. …

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Computer Instructions

In regards to computer instructions, candidates should be able to: explain how instructions are coded as bit patterns explain how the computer distinguishes between instructions and data. Computer Instructions: How are program instructions coded? Machine code instructions are binary numbers and are coded as bit patterns, for example, a 16 bit machine code instruction could …

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Character Sets

Candidates should be able to: explain the use of binary codes to represent characters explain the term character set describe with examples (for example ASCII and Unicode) the relationship between the number of bits per character in a character set and the number of characters which can be represented. How are binary codes used to …

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Software and Operating Systems

For Software and Operating Systems, candidates should be able to: explain the need for the following functions of an operating system: user interface memory management peripheral management multi-tasking security describe the purpose and use of common utility programs for: computer security (antivirus, spyware protection and firewalls) disk organisation (formatting, file transfer, and defragmentation) system maintenance …

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Computer Networks

Candidates should be able to: explain the advantages of networking stand-alone computers into a local area network describe the hardware needed to connect stand-alone computers into a local area network, including hub/switches, wireless access points explain the different roles of computers in a client-server and a peer-to-peer network describe, using diagrams or otherwise, the ring, …

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LMC Addition and Subtraction

Introduction to LMC Addition and Subtraction The following program will demonstrate the ADD and SUB instructions of the LMC instruction set. Instructions Copy the ten line program above and paste it into the Program box. Click on the “Assemble Program” button. After the program is assembled you should see RAM addresses 0 to 8 contain …

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LMC Input and Output

The following program will demonstrate the INPUT and OUTPUT instructions of the LMC.Running the program: the program simply INPUTS a number, then OUTPUTS it. Instructions Copy the three-line program above and paste it into the Program box. Click on the “Assemble Program” button. After the program is assembled you should see RAM addresses 0 to …

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Testing Your Code

Candidates should be able to: describe syntax errors and logic errors which may occur while developing a program understand and identify syntax and logic errors select and justify test data for a program, stating the expected outcome of each test. What are syntax errors? Syntax errors are errors that occur when instructions do not follow …

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Data Structures and Algorithms

Candidates should be able to: define the terms variable and constant as used in an imperative language use variables and constants describe the data types integer, real, Boolean, character and string select and justify appropriate data types for a given program perform common operations on numeric and Boolean data use one-dimensional arrays. What are constants …

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LMC Load and Save

The following program will demonstrate the use of LDA and STA, the Load and Save instructions used in the LMC.Running the program: when prompted, INPUT a set of two numbers. The program should then OUTPUT them in the same order that they were entered. INPSTA firstINPSTA secondLDA firstOUTLDA secondOUTHLTfirst DATsecond DAT 0 INP1 STA 92 …

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Little Man Computer

A Little Man Computer (LMC) is a simulator which has many of the basic features of a modern computer that uses the Von Neumann architecture.

Symmetric Encryption

Symmetric encryption is a form of encryption whereby the same key is used to encrypt and decrypt the message.  This is different from asymmetric or public-key encryption, which uses one key to encrypt a message and another key to decrypt the message. Symmetric encryption is a kind of computerised cryptography, which uses a particular encryption key to conceal the contents …

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Hacking and Malware

Understanding Hacking and Malware: Hacking Hacking is an endeavor to abuse a computer system or a private network in a computer.  It is illegal to access or to take control over computer network security systems for some dishonest purpose. Hackers Hackers are intelligent people and highly skilled in computers.  It requires more intelligence and expertise …

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Converting Decimal to Binary

Converting Decimal to Binary: The Decimal Numbering System Decimal is a base 10 numbering Binary Numbering System Binary is a base 2 numbering system that is made up of two numbers: 0 and 1.  0 means OFF and 1 means ON.  The computer’s central processing unit (CPU) only recognizes these two states – ON and …

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Converting Hexadecimal to Decimal

Hexadecimal Numbering System Hexadecimal is a base 16 numbering system that is made up of 16 digits: 0 – 9 and six more, which is A through F. Uses of Hexadecimal The hexadecimal numbering system is often used by programmers to simplify the binary numbering system.  Since 16 is equivalent to 24, there is a …

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