1.2 software and software development Flashcards
1.2.1 operating systems
hhjkhkhk
types of operating systems
-distributed
-embedded
-multi-tasking
-multi-user
-real-time
distributed operating system
manages a group of independent computers and makes them appear as a single coherent system to users. It allows resources and processes to be distributed across multiple machines
embedded operating system
designed to operate on embedded systems, which are specialized computing devices that perform dedicated functions within larger systems
multi-tasking operating system
executes multiple tasks or processes simultaneously. This is done by using time slicing to switch quickly between programs and applications in memory
multi-user operating system
allows multiple users to access and use a single computer system simultaneously
real time operating system
designed to perform a task within a guaranteed time frame. used in any situation where a response within a certain time period is critical eg) life support system, self-driving cars
virtual machine
a program that has the same functionality as a physical computer
emulation software
Mimics the entire hardware, allowing software from one platform to run on another
intermediate code
simplified Code that is halfway between high level and machine code.
why is intermediate code used
This is independent of the processor architecture so can be used across different machines and operating systems
instance in which virtual memory maybe used
-testing programs
-protection from malware
-running software compatible with different versions and types of operating systems
1.2.2 application generation
lesgooooo
What are the two categories of software?
Applications software and systems software
application software
-designed to be used by the end-user to perform one specific task.
-requires system software in order to run
-Examples: desktop publishing, word processing, spreadsheets, web browsers.
system software
-a low-level software that is responsible for running the computer system smoothly
-Examples: library programs, utility programs, operating system, device drivers
utilities
a program or tool that performs specific tasks to enhance productivity, efficiency, functionality, or maintenance of a computer system
examples of utilities
-file repair
-backup
-compression
-disk defragmentation
-anti-virus
-file management
-device drivers
anti-virus
responsible for detecting potential threats to the computer, alerting the user and removing these threats.
device drivers
piece of software that enables communication between an operating system and specific hardware devices eg)printers
disk defragmentor
As the hard disk becomes full, read/write times slow down. This is because files become fragmented as they are stored in different parts of memory. The
disk defragmenter utility rearranges the contents of the hard drive so they can be accessed faster, thus improving performance.
compression
OS provide utilities that enable file to be compressed and decompressed. Compression reduces the size of a file so it takes up less space and downloads faster over the internet. Compressed files must be extracted before they can be read.
backup
The backup utility automatically creates routine copies of specific files selected by the user. How often files are backed up is also specified by the user. This means that in the event of a power failure, malicious attack or other accident, files can be recovered
(automatically makes a copy of files and stores them in a different location so in the case of losing the original, the files can be recovered)
what is source code
object code before it has been compiled
open source
can be used by anyone without a license and is distributed with the source code. It can be installed on any number of computers and users can modify the software
(source code is freely available for others to amend without needing a licence)
open source advantages and disadvantages
adv: Can be modified and improved by anyone, technical support from online and wider community
dis: Support available online may be insufficient or incorrect, creators get little-to-no financial gain as the software is free
closed source
Closed source code requires the
user to hold an appropriate
license to use it. Users cannot
access the source code as the
company owns the copyright
license. Protected by the copyright design and patents act, users cannot modify the software, usually paid for and licensed per user or per computer.
(software that does not allow users to access or modify its source code. Only the individual or company that created the software can access it)
closed source advantages and disadvantages
adv: Thorough, regular and
well-tested updates,
High levels of security as developed professionally, creators receive an income for their product-licencing fees
dis: Users cannot modify the software to fit their specific needs
translator definition
program that converts high-level source code into low-level machine code which is then ready to be executed by a computer
what are the three types of translators
-compiler
-interpreter
-assembler
compiler definition
advantage
disadvantage
translates source code from high level languages into machine code all at once
ADV: speed of execution is faster, code is usually optimised, no need for translation at run-time
DIS: compilation time, complexity
interpreter definition
advantage
disadvantage
translator that checks a source code for syntax errors line by line, translates it into machine code then executes the line
ADV: instant feedback so easy debugging, source code can run on any machine with the appropriate interpreter
DIS: slower execution,
assembler definition
advantage
disadvantage
a translator in low level language, which converts assembly code into machine code
ADV: memory-efficient, speed of execution, hardware-oriented
DIS:It is difficult to write and debug programs in assemblers, as there is no high-level language syntax to help catch errors
1.2.3 introduction toprogramming
fresge
assembly language
next level up from machine code and is part of a family of low
level languages. This is converted to machine code using an assembler when it is
executed
how does assembly language differ from machine code
Assembly language uses mnemonics rather than binary, which makes it easier to use than direct machine code
what is the function of the STA mnemonic
store- Storing the value in the Accumulator at the given
memory address
what is the function of the BRP mnemonic
branch if positive- Branches to a given address if the value in the Accumulator is positive. This is a conditional branch.
what is the function of the BRA mnemonic
branch always- Branches to a given address no matter the value in the Accumulator. This is an unconditional branch.
what is the function of the HLT mnemonic
halt- Stops the program at that line, preventing the rest of
the code from executing.
