software notes
- Created by: loupardoe
- Created on: 12-06-16 15:19
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What is software?
writing software
- software is written by programmers using programming languages
- programming languages are themselves software
- the CPU can only recognise instructions that are given to it as binary bit patterns
- such instructions are called machine code
- machine code is a low level language which means it works low down at the hardware level
- each machine operation has to be written by the programmer
- writing software in machine code is difficult
- high level languages allow the programmer to set out algorithms without having to worry about every single action carried out by the CPU
- it is difficult to produce robust and reliable software
- writing software is still quite a new activity for humans and there is not a long tradition about how it should be done
- various methods have been invented in order to lay down rules about how writing software should best be approached
- this is the discipline of software engineering
types of software
- system software- software that is written to control and make use of the hardware. acts as an intermediary between the user and the hardware and also between applications and the hardware
- applications are what computer users by computers for. these are programs whcih do the real-world tasks that the users want
- applications need to make use of system software in order to make the hardware do what is required
system software
- consists of operating systems, device drivers, firmware, servers, utilities and interfaces
- often taken to include development tools such as compilers, interpreters, linkers and debuggers
operating systems
- the operating system is a large collection of programs that the hardware what to do
- operating systems are necessary to run all applications, except those which are self booting
- they are found in nearly all computing devices
- oversees such operations as transferring data between memory locations, the CPU and the disks; producing visual displays on the screen; controlling peripherals; protecting data from being accidentally overwritten
- sometimes referred to as a platform
- this means that it provides an environment where applications can run
- applications must be written to conform to a particular platform and this imposes a degree of consistency on them
- applications make use of the kernel to operate the hardware
- ensure that applications are less likely to cause problems with basic memory operations
user interface software
- the user interface is the boundary between the human user and the machine
- lets the user give commands
- asks questions
- displays a response
- operating systems provide different ways of doing these things
- command line interface- requires the user to type commands; these are translated by a command interpreter into signals that the computer can understand; you can completely control a computer system with commands which is why technicians and programmers like using them
- they also find it useful to group commands together in shell scripts to carry out maintenance jobs auomatically
- a shell is software that a user needs to communicate with the kernel
memory management
- operating systems have to decide what goes where in memory
- they have to make…
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