Software Flashcards
Application
Any program, routine or procedures that can be run on a computer system
Assembler
Translates a program written in assembly language into machine code
Assembly code
Plain text code that has a 1:1 translation to machine code
Bespoke software
More expensive- required expertise to analyse software requirements
Features customised to user requirements
Takes a while to develop
May contain errors
BIOS
Basic Input/Output System: part of the operating system that handles the input and output of the computer. It enables the operating system to use the particular features of the hardware being used
Closed source/ proprietary
A types of computer program for which the software code is not shared with the public for anyone to look at or make changes to- Closed / Proprietary type files are often only able to be opened if you own a version of the software they were originally made in
Code generation
The stage in compilation that produces a machine code program that is equivalent to the source program
Compilation
The translation process that produces an equivalent program in a low level language. Compilation involves analysing the language structure of the source program, determining if it is valid, and proceeding suitable machine code
Compiler
Takes source code, translates it all into object code before allowing it to run
Device drivers
Piece if software, usually supplied with a device, that tells the OS how it can communicate with the device
FCFS
First Come First Serve
A scheduling algorithm that deals with each user or task in the order in which they arrive, this can be thought of as a queue
Distributed systems
Form of parallel processing system which spreads the load over multiple computer servers
A single job is split up into several tasks and each of these is run on a separate computer
Coordinated by the OS so that it appears to the user as a single system
Interpreter
Converts a program from a high level language into machine code and runs it
Embedded operating system
Used in washing machines, microwaves etc
Minimal user interface
No RAM so ne memory management system
No permanent data storage devices
Handling external peripherals
Dealing with I/O requests
Using device drivers to communicate with hardware
Interrupt
A signal generated by a source such as an input or output device or a systems software routine that causes a break in the execution of the current routine. Control passes to another routine in such a way that the original routine can be resumed after the interrupt
ISR
Interrupt Service Routine
A software routine that hardware invokes in response to an interrupt. ISRs examine an interrupt and determine how to handle it
Lexical Analysis
The stage in compilation that puts each statement into the form best suited to the syntax analyser. The standard components of each statement, such as PRINT or IF are replaced by their tokens and programmer-defined names are entered into symbol table. The lexical analyser also removes unnecessary characters such as spaces, tabs and coder comments
Libraries
A collection of pre-compiled routines which can be incorporated into a program
Linker
A software tool that allows already compiled object code files ir modules to be combined with the compiled program
Loader
A program that copies an object program held on backing store into main store ready for execution
High level languages
Text based programming languages such as Python or Java
Intermediate code
Half way between high level and low level code. Is a standard across all machine types uses a virtual machine
MLFQ
Multi Level Feedback Queue
A complex scheduling algorithm that deals with tasks based on a set of priorities and rules across different league tables, jobs in a certain table get promoted up or down their table based on these rules and can then end up in totally different tables if they are relagated
Machine code
Binary code that the computer understands
Low level programming languages
Harder to write/ read, like machine code or assembly language
Object code
Code produced by a compiler/ assembler
Open source
Software for which the original source code is made freely available and may be redistributed and modified. Open source file types are often able to be opened on many different types of applications
Opcode
The instruction
Managing the processor
Deciding which process to execute next
Handling interruptions to the running process
Managing the memory
Loading programs
Reusing memory when programs close
Using virtual memory to compensate for lack of RAM
Optimisation
The stage of compilation tat ensures that the executable program is optimised at least as much as the compiler can predict eg. Removing reference to unused variables or routines
Paging
The organisation of memory into fixed-sized units, called pages. The intermediate access store is organised as a number of physical pages. The logical pages used by the SPU can be assigned by the memory management unit to any page in physical memory
Multi-User, Multi-Tasking system
May run on a stand alone computer
Can run many jobs simultaneously
Single powerful main frame is connected to dozens or hundreds of terminals all using the mainframe’s CPU
Each user gets a slice of the processor time according to a scheduling algorithm
Mobile phones
Use Multi-User, Multi-Tasking system
OS on smartphones are called mobile operating systems
Features specifically needed for that device
Tied to a specific hardware
Two operating systems: Main systems (user interface, running apps) Low level proprietary (real time embedded)
RR
Round robin
A scheduling algorithm that deals with each user or task to be processed in time
Scheduling
The method by which central processor time is allocated in a multi access system
Segmentation
The splitting of a large program into a number of smaller programs or segments. Each segment is a complete program that is executed separately. The function of the large program is achieved by running segments consecutively. Segmentation allows a large program to be executed on a computer with insufficient memory to store the whole program by carving up memory logically rather than physically
Off the shelf software
Cheap- cost is shared among clients
May contain unwanted features
Ready to be installed immediately
Well documented and tested
Syntax analysis
The stage in compilation where language statements are checked against the rules of the language, errors being reported if a statement is not valid.
Source code
Original code typed by the programmer in it’s native language. This code is at it appears before it is compiled/ interpreted
Operand
The data the instruction acts on
Operating systems
A set of programs that lie between applications software and the computer’s hardware
Provides resource management (managing the hardware)
Provides a user interface
Real time embedded systems
Used in aircraft and other safety critical systems
Must have very quick response times
Must be able to deal with many inputs simultaneously
Must have ‘failsafe’ mechanisms designed to detect hardware fails and react appropriately
Utility programs
File manager, anti virus, defragmenter, encryption, file compression, installers, clipboard manager, system monitor
Networking
Interfacing to other computers via cable and WiFi
Translator
Translates a program from assembly code to machine cod
Utilities
A systems program that performs some specific task in the operation of the computer, for example file backup, virus checking or a compression program.
Virtual machine
Emulator that acts as a computer
Provides an environment with a translator
Requires an interpreter
