4.6 - Fundamentals of data representation

Hardware - the physical components that make up the computer Software - programs that are run by the computer Hardware needs software to run; software needs hardware to run on

Software that runs and manages the computer’s hardware and application programs eg. operating systems, utility programs and translators

Software that allows the user to complete different tasks Types: General purpose Special purpose Bespoke

Software that can be used for a variety of tasks e.g. word processors, presentation software

Software that can only be used for one particular task e.g. scientific calculator software - can only carry out calculations

Software that is developed to meet the user’s specific requirements e.g. self-service touchscreen kiosks at fast food restaurants

A collection of programs that controls the operation of computer hardware

Processor management (processor scheduling) - determines the order in which processes will be executed, allowing for multi-tasking Inputs, outputs, and interrupts (input/output device management) - ensures efficient communication with devices and manages functionality issues Memory management - records how memory in the computer is divided and identified so that it is allocated efficiently between running processes Secondary storage management - tracks where files and programs are stored, which parts are available for storage, and manages files and folders based on user permissions Security - ensures that resources are protected from unauthorised access through the use of permissions and passwords

Machine-oriented/non-portable - defined by the processor they are designed to run No built-in functions Can access specific registers in the processor A 1:1 relationship with processor instructions Programs typically require less memory and execute faster than a high-level language program performing the same task

Opcode - part of the instruction that specifies which operation the processor should perform Operand - contains a value, or set of values, relevant to the opcode; can be an actual piece of data, or a reference to the memory location of the data for the opcode to act on

Immediate - operand interpreted as a data value (01) Direct - operand interpreted as a memory address (10)

Allows programmers to: - Create optimised programs - More directly control how resources are used when they are limited

No 1:1 relationship with processor instructions - a single line of code can accomplish multiple tasks Has to be translated into machine code for the computer to process Offers development tools such as libraries and built-in functions Problem-oriented rather thanmachine-oriented - typically designed to handle a particular problem High levels of abstractions from the details of the computer - makes programming much more convenient and allows the programmer to write shorter, cleaner code

Mucheasierto write programs in them - they use normal command words such asIF, ELSE AND FOR, so it is much easier for a human to make sense of the program Portable - can be compiled or translated to run on a wide range of computer architectures; they are not specific to a particular instruction set Libraries of functions - can be imported and used by the programmer, allowing them to take advantage ofpre-written code

A language used to write a list of instructions to solve a problem, where the programmer defines how the problem should be solved

A language used by the programmer to define what the problem to be solved is rather than how to solve the problem

A language that programmers use to define objects and classes that define the data and the instructions to manipulate it

Translates code into a form that can be executed but does not execute the code Takes the source code as its set of instructions, which it then puts through a series of processes to produce executable code

Produces executable code in a form that cannot be read by a human or readily reverse-engineered - advantageous to commercial developers who make money from their code When the program has successfully compiled, the executable file will not need to be translated again (unless the source code is changed) - faster running times User doesn’t need a translator (i.e. interpreter) to be installed on their computer as they will never need to translate the program themselves

Any compilation errors are reported at the end of the compilation process Compiled code can only be executedon a machine with the same processortype/instruction set

Each program line, when run, is syntax-checked - program halts and reports errors it finds Each line of source code is converted into its machine code equivalent and executed

Easier to debug during the testing stage of development - errors are reported and can be fixed when they occur More portable - can be advantageous if the programmer does not know which platform will be used to run the code Less memory than an executable file - only few lines of source code needed at any one time

Source code that is interpreted runs more slowly than compiled code - each time the program is run, it must be translated all over again User must have the interpreter installed to be able to run the program Doesn’t protect the source code