Computers are very accurate. Computers can work 24 hours per day, 365 days per year. Computers make some jobs possible. Disadvantages of using computers Computers can replace people's jobs.
Computers hold personal information which could be misused. Computers can fail and without them the Job may not get done. Processing data Computers can: calculate sort search store draw. Revision notes: Module 1 2 Operating systems An operating system (SO) is a set of programs that controls how the hardware and applications of a computer works. An SO is the way of communicating between the user and the computer. The SO loads and runs the other software application programs and other Jobs.
The operating system on a computer meaner that usually only certain applications will run on that computer.Functions The operating system: enables communication between the user and the computer; loads and runs applications programs as well as other Jobs; will only run applications written for that particular type of SO; handles input and output: - taking data from the input devices and sending it to RAM; - taking output and sending it to the correct output device; handles the transfer of data from memory to and from the backing storage devices; allocates memory space to programs and data; loads and runs the applications software in memory; handles any errors while the software is running; manages system security, with user ID and passwords; provides a human-computer interface, or HCI, for the user. Human- computer interface (HCI) This is the method by which the users communicates with the computer, sometimes called the user interface.Two type of HCI are: command- line interface graphical user interface or GIG-Jell. Command-line interface The user types in the instructions using command words.
The main advantage of command-driven interfaces is that, providing the user knows the commands, they can be quick to carry out, since they require less translation by he SO than Guise. They can also be used in batch files to carry out repetitive administration tasks that would take a long time using a GIG-Jell. Graphical user interface The most widely used type of graphical user interfaces are WIMP (Windows Icons Menu Pointer) systems. The main advantage of a GUI it is easy to use. The main disadvantage is the large amount of memory, RAM and disk space that is needed.Revision notes: M Software doodle 1 3 There are two main types of computer software - system software and application software.
Application software is used in particular situations and can be general- repose (the same software used in differing situations) or specialist/custom-made (can only be used in one particular situation). General purpose A general-purpose application package (generic) is software that can perform different related tasks. Word processors, spreadsheets, databases, graphics and presentation software are all examples of application packages. They are: relatively cheap readily available can generally be installed quickly and easily thoroughly tested well supported with books and on-line help.
Generally, networking between the different applications is made easier with integrated packages. Specialist software Specialist application software performs only one particular task. Examples include software for payroll, accounts, stock control, route planning and weather forecasting. Types of computer Mainframe computers Mainframe computers process large amounts of data and do so very quickly. Backing storage is provided on lots of disk drives. A mainframe can have a large number of users connected to it at the same time.
The most powerful mainframes are called 'supercomputers' and are used for processing even larger and more complex amounts of data, such as in weather forecasting.Personal computers A typical PC system consists of: a base or tower unit that contains the processor, backing storage devices (hard disk drive), DVD drive, USB connections, Firmware and other connections; input devices, normally a mouse and keyboard; output devices, typically a screen, printer and speakers. PC's are single- user computers and used to be called 'microcomputers'. Laptop (notebook) A laptop is n example of a portable computer. Screens are typically 35-CACM (14-inn) and are used whilst traveling or at meetings.
Notebook A notebook is an even smaller version of a laptop, screens typically 20-CACM (8-1 Ion). Palmtop and PDA (personal digital assistant) Pads are small hand-held devices with limited functionality (diary, contact lists, email). Palmtops are small computers with a small number of applications which can be synchronized with the main network system.If the PDA also has mobile phone capability, this is known as a 'semaphore'. Revision notes: Module 1 5 Microprocessors A microprocessor is a single integrated circuit (chip) that performs the functions of a central processing unit (COP]).
Microprocessors are used to control devices such as washing machines, videos, burglar alarms, etc. Advantages of microprocessors Reliable - no moving parts. Chips are cheap. Programmable - so able perform different functions. Disadvantages of microprocessors Wasteful to replace whole unit when it could be repaired.
Many of the extra features/programs may never be used. More complex - more to go wrong and break down. Revision notes: Module 1 6
