5 - system software Flashcards
1
Q
User system interface
A
- allows the user to get the hardware/ software to do something useful
2
Q
GUI
A
graphical user interface
- uses WIMP - windows icons menus and pointers
+ simple to use (intuitive)
+ looks nice
- limits what you can do
- needs OS
for general population
3
Q
CLI
A
- is text based - through a keyboard
+ can debug
+ directly manipulate functionality of computer
+ can alter comp settings
+ don’t need OS - harder to use
- need to learn complex commands
more advanced users
4
Q
program hardware management
A
- OS ensures hardware does what the software wants
- Program development tools allow the programmer to write a program without knowing how the hardware actually works
- OS provides a mechanism to run the program
5
Q
BIOS
A
- Basic Input/Output System
- Stored in CMOS memory - so can be altered or deleted as required
6
Q
OS - management
A
- memory
- security
- processor
- hardware
- file
7
Q
security management
A
- Ensures integrity confidentiality and availability of data
- Updates system when available
- Ensures anti virus is up to date
- Communicates with firewalls to check traffic
- Makes use of privileges
- Maintains access rights
- Offers recovery of data
- Prevents illegal intrusion
8
Q
processor management
A
- Allocation of recourses
- Permits exchange of data
- Allows processors to be synchronised (schedules resources, resolves conflicts, use of queues)
9
Q
hardware management
A
- Communicates with I/O devices - using drivers
- Translates data from a file into formats I/O devices understand
- Ensures hardware has a priority so can be used as required
10
Q
file management
A
- Defines file naming conversions
- Creates, opens, closes, deletes, renames, copies and moves files
- Maintains directory structures
- Ensures access rights, passwords, locking files are maintained
- Specifies the file storage format (FAT, NTFS)
- Ensures memory allocation for a file by reading from HDD/ SSD and loads into memory
11
Q
memory management
A
- made up of memory optimisation, organisation, protection
12
Q
memory optimisation
A
- how memory is allocated and where programs are stored
- keeps track of all allocated and free memory
- swaps data to/from HDD/SSD
13
Q
memory organisation
A
- how much memory is allocated and how its split up approrpriately
- single contiguous allocation, partitioned, paged memory allocation, segmented memory
14
Q
single contiguous allocation
A
- all memory is made avaiable to a single application
15
Q
partitioned allocation
A
- memory is split into contiguous partitions and memory management allocates a section to an application
16
Q
paged memory
A
- each partition is a fixed size - used by virtual memory
17
Q
segmented memory
A
- memory blocks arent contiguous each segment is allocated to a logical group of data (eg data that makes up an array)
18
Q
memory protection
A
- ensures competing applications cant use the same memory locations at once
- if not data could be lost, security issues or comp can crash
19
Q
error
A
- Can be because the program was badxly written or supplied with inappropriate data
- System needs to be able to interrupt processing and provide error diagnostics or shut down the system if extreme errors
20
Q
utility programs
A
- hard disk formatter
- hard disk repair
- hard disk defragmenter
- backup
- file compression
- virus checker
- disk content analysis/repair software
21
Q
hard disk formatter
A
- Organises storage space by assigning it in data blocks/partitions
- After partitions are created they are formatted - writes files to hold directory data and table of contents
- NTFS - full formatting for windows - fills with zeros then reads them back to test the sector
- If bad sector is found its flagged and reorganises by replacing bad sectors with new unused sectors
22
Q
hard disk repair
A
If bad sector is found its flagged and reorganises by replacing bad sectors with new unused sectors
23
Q
hard disk defragmenter
A
- When disk becomes full sections of files will be scattered - read/write is slower as arm has to move more
- Defragmenter arranges files to store in contiguous sectors + faster read/write - can also carry out clean up operations
24
Q
backup
A
- Allows a schedule for backing up e.g. every week
- Only backs up if changes are made
- For security should be 3 versions of any file
- current version on comp e.g. hard drive
- locally backed up e.g. portable SSD
remotely backed up e.g. cloud storage
25
file compression
- Compresses data before writing to hard disk
+ Saves storage space - makes upload/download quicker
26
virus checker
- Checks software or files before they are loaded on a comp
- Compares possible viruses against a database of known viruses
- Carries out heuristic checking - checks for types of behaviour that could indicate a virus
- Puts infected files into quarantine - deleted the files or allows the user to decide whether to open
- Update software to keep virus database up to date
27
disks content analysis / repair software
Checks for empty space by reviewing files - can remove unwanted files/downloads
28
program libraries
- used when software is being developed can use pre-written subroutines and save time
- used to help developers who want to use DLL in their programs
+ saves time as removes the need to rewrite the subroutines
+ several programmers can be working at the same time (modular programming)
+ allows continuity in games
+ can maintain a corporate image
+ saves testing. times
29
static vs dynamic libraries
**static libraries** - software is linked to executable code in the library - routines would be embedded directly into the new program
**dynamic libraries** - not linked to the library routines until run time – the routines will be available to several applications at the same time
30
assemblers
- Converts an assembly language program into machine code
- can be a two-pass assembler
- First - removing comments, symbol table creation, expansion of macros, identification of system calls
- second - replaces symbolic addresses with absolute addresses and creates object code
31
compilers
- translated into machine code
- output object code
- can be executed many times without being translated again
32
interpreter
- executed line by line
- shows errors when it sees them
- every line is interpreted each time the program is run
33
compiler +/-
+ no need to have a translator
+ source code can't be changed by end user of object code
+ quicker to execute
+ no syntax or semantic errors once compiled
+ can be translated on one comp then executed on another type
- list of errors at the end
- untested errors may cause a crash
-end users done have access to source code
34
interpreter +/-
+ easier to debug
+ can see partial results during development
+ if purchased end users have source code
- end user needs interpreter
- end users can use source code - copywright
- can contain syntax errors
- can't be run on diff comp typed
35
IDE
integrated development environment
- used by programmers to aid the writing and development of programs
IDEs usually have
- a source code editor
- a compiler, an interpreter, or both
- a run-time environment with a debugger
- an auto-documenter
36
source code editor
- Allows program to be written without separate text editor- can edit without changing software
- Layout with prettyprinting - colour coded
-context sensitive prompts eg text completion
- Flags syntax errors - logic errors can only be found at run time
37
run time environment with debugger
- Flags errors
- can step through the program line by line - single stepping
- set a breakpoint - stops the execution of the program
- Report window - shows contents of variables/expressions at that point in the program - can check for logical errors
38
auto documenter
- explains the function of the code and each built in function
39
partial compiling and interpreting
- Source code is checked and translated by a compiler to object code
- This is known as intermediate code, p-code or bytecode
- To execute the object code can be interpreted by an interpreter
- Eg Java and python
