1.2 System Software Flashcards
What does the operating system do?
- It manages the physical resources of the computer. Some resources are limited and must be managed to maximise the use of the computer system.
- It provides a user interface
- It provides a platform on which the application software can run
- It controls access to the computer system, allowing the user to put passwords on files
When using application software are you directly communicating with the computers hardware?
No - The application software communicates with the operating system which communicates with the hardware on its behalf
Without an operating system the computers useless no matter how many program’s there are
What is batch processing?
A type operating system that doesn’t allow any interaction between the computer and the user. Lots of data are collected together to for a batch and they are processed all at once.
What are the uses of batch processing?
- Where there are large amounts of data to be processed
- When the data are very similar in nature and require similar processing
- When the computer system has identifiable times when it is not being used and so has available processing time
- When the application doesn’t require user interaction
Give examples of when batch processing would be useful
- The processing of pay roll information
- The production of bank statements from customer files at periodic intervals
- Production of utility bills from customer records
What is a realtime operating system?
An operating system that can react quickly enough to affect the next input or process that needs to be carried out
- There is a continuous cycle of input, process or output and there is no waiting time between init and processing
- The processor almost always must be dedicated to the running job and cannot multitask
What are some of the uses of realtime processing?
Most realtime systems are used in real world situations (where they process on a time scale of milliseconds), such as:
- A computer that controls the temperature in chemical plants reaction vessel. It receives input from a monitor. It uses realtime processing to ensure that the temperature stays within a certain range.
- A processor that controls a robot trolley and ensure that it doesn’t go beyond a black line. The processor receives input from a sensor. It uses realtime processing to ensure that the trolley stays within the black line.
What is a single user operating system?
An operating system which has only one user and their program’s at a time
-Exclusive access to processing and storage facility for a single user
- However it’s idle most of the time
- User usually doesn’t use the full processing power
Where would a single user operating system be used?
On a stand alone computer or a laptop it would be used so that only one person uses the computer system at a time but there can be different users at different times.
-This means security measured are important so that files are accessed by the right user
What is a multi user operating system?
An operating system that allows the computer to service more than one user simultaneously
- There are two types of multiuser operating system:
- The network OS
- The time sharing OS
How does the multi user operating system work?
In the network OS
-There is a single computer which is connected to a number of terminals. These terminals are not computers and have a very limited amount of processing power, therefore they rely on the main computer to carry out processing.
In the time sharing OS
-The computer sends a message to each of the terminals, asking if it wants any processing to be done. This is called a time sharing system or a round robin system, where each terminal gets a small amount of processor time called a time slice
How do you ensure a time share system operates effectively?
- The main computers also known as a server and it saves the application software and user data files.
- The system needs to be fast enough that a user doesn’t have to wait for too long before being given processor time
- The response time for all users should be acceptable in order for this method to be effective
What are the advantages and disadvantages the network OS and the time sharing OS?
In the network OS
- Centralised servers are more stable
- Security is provided by the server
- Cost of buying and running are expensive
- Requires regular maintenance and updates
In the time sharing OS
- It allows processing and storage to be utilised at full extent
- Hardware and software is shared
- Increases the risk of failure
- Data security is of concern
What is a multitasking operating system?
This is an operating system that allows several applications to be available simultaneously
-This is done through the processor switching quickly between each program
What is the user interface?
This is the way in which the computer system interacts with the user
This is also known as the human computer interface (HCI)
-The users give an input (e.g. The click of a mouse) and the computer gives a response
What is the form based interface?
This is an interface that allows the user to input information into an on screen form. This is very useful if the majority of the input to a system is standardised.
-An example where this would be used is an operator inputting informations about a customer, into a database
What are the advantages of the form based interface?
This interface:
- Prompts the user to ask each of the questions in turn
- Makes the user input information in the correct order and ensures that nothing is missed out
- Ensures that the user enters the information in the correct format
- Makes the checking of information easier
How is a form based interface layer out?
In this interface there can be:
- A drop down list for restricted input, such as the persons title or a date
- Boxes for textual information, like the name or address of a customer
- Check boxes for yes or no information
What is a menu based interface?
This is an interface used in situations where the user is unsure of the options available
-An example of this is information systems used for tourists. A list of choices is displayed and when the user selects an option, a further set of choices is displayed, and so on until a result is achieved
What is the graphical user interface (GUI)?
This is the use of windows, icons, menus and pointers (WIMP) by the computer to interact with the user
- The user of the GUI expects it to be able to view different applications or files on the screen at the same time. This is done by putting each application into its own bordered are known as a window
- The user can select a command by clicking on a small picture (icon) that represents it and the user selects further options from menus, these are selected through the use of a pointing device such as a mouse
Give an example where GUI can be used
The whole principle of GUI is to make using the system as simple as possible by hiding all the complicated bits
An example of this is when the user clicks on an icon that brings a piece of software to the screen, it involves only the action. However in the backgrounds, the computer is executing a complicated process involving a lot of instructions
What is the natural language interface?
This is when the computed displays or speaks questions that gives the user the impression that the computer is talking to them
However the system restricts itself to questions that will provoke very simple responses which the computer can understand and the user must give an expected answer
What is the command line interface?
In this interface, the user types a series of commands on the keyboard and the computer displays an output
-The computer doesn’t prompt the user to enter any particular information. If the user types a command incorrectly, the computer will output an error message
In a command line interface, what is required of the user?
In a command line interface the user must:
- Know what commands are avaliable
- Understand the commands
- Understand how material is stored in the computer
