HCI -Interfaces

Question	Answer
HCI (Human Computer Interface) Image: HCI1 (image/png)	The HCI is most commonly referred to as the user interface and it determines the way the user interacts with the computer.
Command-line interface	Users type instructions using specific words/symbols. It was used in the early days and is good for skilled ICT users to give a set of instructions to the computer.
Advantages of command-line interface:	The advantages are that the instructions are executed quickly, instructions are versatile (meaning that the users can input a lot of instructions) and the operating systems are smaller when loaded into memory.
Disadvantages of command-line interfaces:	The disadvantages are that you need to learn the special instructions needed, if it's mistyped and spelt wrong then the instruction wont happen, high level ICT need as commands are complex.
Menu driven interface:	A menu of options appears so the user can choose one. it's more user friendly than command-line interfaces because the instructions don't need to be remembered.
Advantages of menu driven interface:	The advantages are that Navigation to find an option required is simple and you do not need to learn what instructions are available as they are displayed in the menu. User input is validated as only the options shown can be used
Disadvantages of menu driven interface:	Some options in a menu may not mean anything to the user. It can be difficult to find options if there are many menus and sub-menus
Graphical user interface (GUI)	Small pictures are used to represent options you can click.
Advantages of GUI	The advantages are that most are used to help users when they are having difficulties. Only a low level of ICT is needed. As It is easy to use. No instructions. You can alter/personalise it.
Disadvantages of GUI:	The disadvantages are that it large and may cause the computer to run slow.
Voice interface:	A microphone is used so the user can talk to tell instructions to the computer.
Advantages of voice Interfaces:	The advantages are that it can be used without using hands so people with disabilities can use them too.
Disadvantages of voice interfaces:	The disadvantages are that people speak differently so the computer may have difficulty understanding everyone. Also the use of different languages impeed it.
Special devices:	Special devices are used so people can use a computer even with disabilities e.g using braille keyboards foot switches for people with no arms.
Advantages of touch sensitive interfaces:	The advantages are that they are simple and easy to use. Only low level of ICT is needed to operate it. There is little chance of damage or theft.
Disadvantage of touch sensitive interfaces:	The disadvantages are that the scram can become dirty or scratched so that Its hard to read.
Onscreen help: Image: onscreen_help (image/png)	onscreen help is designed to help users navigate around the computer if they don't know how to or need assistance.
In older versions of Microsoft office, there was an Office Assistant which popped up to give context-sensitive help. After a while this could become annoying and it was often turned off.	Most software has some way in which help can be obtained. Sometimes this is generalised help, sometimes it is known as context-related help as it gives you help about the part of the software you are using at the moment.
Point of sale interface:	A point of sale interface is used to provide information e.ga till at a supermarket that tells the cashier the price of an item and its stock details e.g how many left in stock.
Biometric Systems:	Biometric systems are things that use physical characteristics to identify people e.g. finger prints, Voice , fascial features and eye scanners.
Image: Biometric (image/jpg)	examples of biometric. (opposite)
Image: computer_software. (image/png)	Computer software is needed so the user can write and produce work using a computer.A program is a set of instructions that tells a computer what to do. Software is defined as the programs that run on a computer system. Software is usually divided into two main types
2 types of software: Applications software: programs that perform a specific task (e.g. stock control program or computer game) and generic programs that can be used for general-purpose tasks (e.g. a word-processing program).	The software types are Systems software: programs that help a computer system to work (e.g. operating system, disk defragmenter and compilers)
Image: operating_systems (image/png)	Operating systems are: A computer will not run without an operating system, as it is the program that controls the running of the computer. When a computer is switched on the first thing that happens is that the operating system is loaded into memory, usually from the hard drive.
The computer is designed with a small amount of software on a ROM chip, which allows the computer to find the main part of the operating system on the hard drive. This process is called booting.	An operation system can carry out the following functions: It loads and runs programs. It maximises the use of memory (RAM) . It handles inputs and outputs. If interrupts occur, then it deals with them. It maintains the security of the system.
Single-program: Batch- Processing systems:.	Single-program is where a computer can only have one program open at any 1 time. Batch-processing systems allow a user to hold a queue of jobs waiting to be done .It is mostly used in businesses.
The advantages of batch-processing is that processing can be done off peak-times. Also, no human intervention is required once the batch has been started.	Multi-programming system The computer holds more than one program in its memory and gives each one a small amount of processing time in turn. This happens so fast that it seems to the user that the computer is running more than one program at a time. It is the job of the operating system to share the resources, such as processing time, so that each program is eventually completed successfully.
Multi-access Systems:	Many users can use the same computer at the same time without any difficulties. A mainframe connects all the computers to one mainframe. The workstations are made up of input devices (e.g. keyboard and mouse) and a monitor but there isn't a computer unit.
There is no computer unit because they are connected to the mainframe computer. However, networks are starting to replace the mainframe computer.	Distributed Systems:
In a distributed system, the processing and resources are shared between a number of different computers. It is the operating system that has to make sure that each of the computers in the system communicates properly.	In a distributed system, the processing and resources are shared between a number of different computers. It is the operating system that has to make sure that each of the computers in the system communicates properly.
Real-time systems:	Data is processed as soon as it is input into a real-time system. A process control system is an example of a real-time system. Sensors monitor a process by taking environmental measurements and sending them to the computer as input. The computer processes the data immediately and takes action if necessary. The system can react fast enough to be able to take actions in abnormal situations such as a machine breaking down or even a fire.
Another example of a real-time system is a flight simulator used to train pilots. Real-time operating systems can be found in embedded computers. The operating system is stored in a ROM chip and runs and manages a single program that operates such as a washing machine or a digital camera.	Another type of real-time system involves transactions. Every time an item is sold or bought, or a booking is made, the data from the user is processed immediately. This may involve updating some data held in a record of a database. The transactions are processed in the order they are received and each transaction is completed before the next one is processed.
Parallel- Processing Systems:	Some larger mainframe computers have more than one processor. These are large mainframes with hundreds or even thousands of processors. Large tasks are completed faster if they are shared between a number of processors.
Special programming languages have been developed to write applications for parallel-processing systems and complex operating systems are needed to share out the tasks to the processors and coordinate their activities.	Computers that process large quantities of data, such as weather-forecasting systems, use parallel processing.
Interactive Systems:	A user inputs a command to a computer, which may then respond with a request for further input of data. This is interactive computing: it is similar to a conversation between a user and the computer. An example of interactive computing can be found when you take case out an ATM.
System Security:	One of the tasks of an operating system is to maintain security. This means protecting the system from malicious or accidental damage by users. Damage may involve changing a data file or even deleting it. Security on single-user systems is different from security on multi-user systems.
Single-user security involves protecting files of data from accidental change or deletion and there is less need for protection from unauthorised users than there is on a multi-user system or network.	On a multi-user system, the username and password are checked every time a user logs on to make sure they are authorised. A log is kept of computer usage. The time when a user logged on and how long the user used the computer are recorded.
The time and date when a file was last changed are recorded. This means if a file has been deliberately changed, it may be possible to track down who was using the computer at the time. The attribute of a file can be set to “read-only”. This would make it impossible to accidentally change or delete an important file.	If a file is deleted, it may be put into a “recycling bin” and if the user discovers that a mistake has been made then the file can be recovered. Tasks such as taking back-ups can be scheduled to occur at regular times.
Other software may be installed which protects the files on a computer from being changed by viruses. In practice, a combination of security measures needs to be in place.	It is worth remembering that the security of a system is only as strong as its weakest link. For example, it would be no good having really strong protection against viruses if the protection against hackers is weak.

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	Created by Amie Griffiths over 10 years ago