Computer Systems: Chapter 5 (Computer Software) Flashcards
What is the bootstrap loader?
The bootstrap loader is a program held in ROM that loads the operating system when the computer is switched on.
What are the 6 main functions of a single user operating system?
- Interpreting user commands
- File management
- Memory management
- Input/Output management
- Process Management
- Resource allocation
What is the Computer Language Interpreter? (CLI)
The CLI is the outer layer of the operating system, which the user interacts with in order to give instructions to the computer
What is the File Management System? (FMS)
The FMS is the second layer of the operating system, and it organises and tracks files
What are the functions of the File Management System (FMS)? (2)
- Maintaining a directory which keeps track of where files are stored
- Providing a connections between the user’s logical view of the files and the actual physical location of the files
What is the Memory Management System? (MMS)
The MMS is the third layer of the operating system, and controls where programs and data are placed in memory
What are the functions of the Memory Management System (MMS)? (2)
- Monitoring the use of memory
* Freeing memory locations where data is no longer needed
What is the Input/Output Management System? (BIOS)
The BIOS is the fourth layer of the operating system, and it communicated directly with the peripherals and handles the transfer of data between the peripherals and the processor
What are the functions of the Input/Output Management System (BIOS)? (2)
- Data buffering to regulate the speed between the processor and main memory
- Detecting errors such as mechanical or electrical faults
What is Process Management?
Managing processes takes place in the Kernel, which is the bottom layer of the operating system. The Kernel manages processes and handles any interrupts.
What are the functions of the Kernel (Process Management)? (2)
- Schedules CPU time
* Maintains the integrity of the process
What is Resource Allocation?
Resource Allocation is the way of managing which resource is available for use at any one time by a process
What is a Utility Program?
A Utility Program is a program designed to carry out .specific tasks related to the management or maintenance of a computer system
What are examples of Utility programs? (3)
- Virus Checker
- Disk Editor
- Disk Defragmenter
What is a Virus Checker?
A Virus Checker is a program that can detect a virus infection and remove it from a computer system
What is a Disk Editor?
A Disk Editor is a program that allows the user to get rid of any unnecessary files that clutter up a system.
What is a Disk Defragmenter?
A Disk Defragmenter is a program that rearranges the contents of the hard disk so that data blocks that make up files are next to each other.
What are 2 advantages of using a Disk Defragmenter?
- It speeds up access times
* It frees up space
Name 3 standard graphic file formats
- .jpeg (joint photographic experts group)
- .gif (graphics interchange format)
- .tiff (tagged image file format)
What are the advantages of using a .jpeg? (2)
- It uses lossy compression to cut out data which cannot be seen by the human eye
- They take up less storage space than most formats so can be sent easily
What are the advantages of using a .gif? (2)
- Only uses 8 bit colour so takes up less space
* It uses lossless compression so can be used on the Internet
What are the advantages of using a .tiff? (2)
- Uses 24 bit colour so can be used in desktop publishing packages
- It can represent every type of graphic from monochrome to greyscale graphics
What software would you used to produce a multimedia catalogue and why? (2)
- Mediator Pro 7
- It is a multimedia authoring package
- It allows you to create interactive multimedia presentations combining text, sound, graphics and video
What software would you use to set up a LAN in a school and why? (2)
- Windows 2000 Professional
- It is a network operating system application
- It allows you to configure network aspects such as the security, group permissions and network protocols
What software would you use to produce a school website and why? (2)
- Microsoft FrontPage
- It is a web authoring package
- It allows you to create web pages using a full GUI interface, and gives you access to feature such as page templates and sound and video
What are 3 software compatibility issues?
- Memory requirements
- Storage requirements
- OS compatibility
Why is memory requirement a software compatibility issue? (2)
- Software needs RAM to hold programs and data when it is being processed
- If there is not enough RAM then it will take too long to process.
Why is storage requirement a software compatibility issue? (2)
- Software requires a certain amount of backing storage space to be installed
- If there is not enough space then a program cannot fit in backing storage
Why is OS compatibility a software compatibility issue? (2)
- Some software will have been designed for one specific operating system
- If a computer does not have a certain type of operating system then software may not work on the computer
What is a virus?
A virus is a destructive piece of software that attaches itself to a file, reproduces itself and spreads to other files.
What is a worm?
A worm is a destructive piece of software that spreads from computer to computer via security holes in a network, and then reproduces itself.
What is a trojan horse?
A trojan horse is a piece of software that appears to be carrying out a legitimate operation, but is secretly damaging or copying files in the background.
What is the difference between a virus and a worm?
A virus needs to attach to another file to spread from computer to computer, a worm does not need to.
Name 3 typed of viruses
- File virus
- Boot sector virus
- Macro virus
What is a file virus?
A file virus attaches itself to an application file, and is then activated when the program is loaded
What is a boot sector virus?
A boot sector virus infects the system files that your computer uses every time you power up
What is a macro virus?
A macro virus is when a destructive macro is attached to a file, and when it is opened this macro duplicates itself into the macro library and spreads even further
Name 4 techniques used by a virus to disrupt a system
- Replication
- Camouflage
- Watching
- Delivery
What is ‘replication’?
Replication is when a virus makes copies of itself to infect other files on a computer
What is ‘camouflage’?
Camouflage is when a virus disguises itself to avoid being detected by anti-virus software, by adding fake instructions to mask its distinct virus pattern.
What is ‘watching’?
Watching is when a virus waits until a particular action or data before its activated, to infect the greatest number of systems
What is ‘delivery’?
Delivery is the method in which the virus carries out destructive tasks to computer systems to infect them
Name 4 techniques used by anti-Virus software
- Searching for virus signatures
- Use of checksum
- Memory resident monitoring
- Heuristic detectors
What is ‘Searching for virus signatures’?
Anti-virus software looks for virus signatures, which are characteristic patterns of bytes which are parts of virus, to notify the user of the virus in the file.
What is ‘Use of checksum’?
Anti-virus software can carry out a calculation using binary values of an uninfected program. If this calculation changes after it has been run, then the code has been altered, possibly by a virus.
What is ‘Memory resident monitoring’?
Anti-virus software can constantly monitor a computer for the presence of viruses when it’s switched on. If any unusual activity is detected the user is notified.
What are ‘Heuristic detectors’?
Anti-virus software can look for code that would generally be considered to look like a virus, and notifies the user of these viruses.
Why does Fragmentation reduce system performance? 2)
- Unused data blocks are spread across a hard disk and each requires a separate disk access
- This slows down access times for files made up of these blocks
