- User interface- this provides a way for the user to control the computer. The interface lets the user give commands, asks questions and displays responses e.g. GUI (Graphical User Interface) uses Windows, Icons, Menus, Pointers which is less easily customisable whereas command line interfaces let users directly type in commands allowing customisation.
- Memory Management- Programs that the computer is currently running that are in use need to be stored in RAM memory. The computer possesses a set amount of RAM which the OS is responsible for allocating to each program that the user loads.
- Peripheral management- Computer systems have peripherals to input, output and store data which need to be told how to communicate and interact with the rest of the system. Device drivers are produced for each peripheral, programs that enable communication between the computer and peripherals.
- Multi-tasking- A multi-tasking OS allows several processes to be resident in RAM at the same time, in different states: running, runnable or waiting. This is efficient and enables the CPU to complete more tasks in a shorter time.
- Security- The OS must protect programs from each other. If a process is using a certain part of RAM to temporarily store data, another process must not be able to overwrite that data. Most OS systems come with built in measures to protect system security.
(b) describe the purpose and use of common utility programs for computer security (antivirus, spyware protection and firewalls), disk organisation (formatting, file transfer, and defragmentation)
Computer security:
- Antivirus- This searches the computer for viruses and removes potentially harmful code. It is crucial to keep this software updated to combat new threats which are released constantly.
- Spyware protection- Protects from malicious software that detects what a user is doing and sends these details back to the originator (e.g. Trojan programs- harmful software disguised as something else which can steal sensitive data)
- Firewalls- Software which can restrict incoming and outgoing access to certain network addresses.
Disk Organisation:
- Formatting- this enables files to be moved by the user, renamed and copied using format tools.
- Defragmentation- reorganizes files that have been split up into fragments, relocating them together for faster access.
(c) discuss the relative merits of custom written, off the shelf, open source and proprietary software.
Translator programs:
Compiler- translator programs that convert high level source code into machine code, translating an entire block of code at a time.
Interpreters- translator programs that also translate source code into machine code however they translate code line by line, making them useful for debugging.
Types of software:
- Custom written software- Specifically made for a particular client. This type of software is expensive as development costs are borne by only one customer. It takes a long time to develop and test and there are more likely to be faults as it hasn't been tested by users. If there are problems, however, it is easier to contact developers.
- Off the shelf- This is available straight away, sold 'as is'. Many users have worked with it so most bugs will have been discovered and fixed
- Open source software- This is placed in public domain with the source code available to all, making it free and easily accessible. However, there is no one to contact directly if problems occur and there are no maintenance contracts e.g. Firefox
- Proprietary software- This is developed by a company for profit, meaning that users must buy a licence to use it. It can be expensive however it has been extensively tested and help is easily accessible if necessary.
No comments:
Post a Comment