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... before it can be used. It is however possible to stop this file fragmentation happening by running special software that comes as standard with the windows operating system. The software finds all the broken up parts of the file and pieces them back together so that the whole file is saved on continuous clusters. 4 Interface hardware and software Bios The BIOS or Basic Input Output System main function in a computer is to provide standard program interfaces to perform hardware-oriented functions such as writing to the screen and accessing disk drives. This happens when the computer is first powered on, the BIOS will locate all disk drives and video cards and configure them so that they are ready for any DOS program to call upon them or use them. The BIOS is stored on a non-volatile EPROM, this stops it erasing itself when power to it is lost after shut down.
Once the BIOS has found and configured all the hardware, its next task is to execute the operating system that is stored on the system and load it. Adapter cards The use of adapter cards is beneficial to anyone who wishes to make their PC do tasks that is currently can not do, this maybe connecting to a network or editing video footage. Adapter cards are used to add new features to a computer, this maybe such as adding a TV tuner or a network card to the system. Adapter cards plug directly into the motherboard through a small selection of ports, these are the ISA, PCI and AGP ports. Each has its own benefits and drawbacks. ISA ports are now old technology and are not used for many purposes as the through put of the bus that is runs on is very slow indeed, devices such as analogue modems or network cards may still use this port.
PCI is a much faster and newer port; it runs on a 33 mhz bus that is fast enough to cope with much more data throughput then the ISA bus. This makes the PCI port good for adapter cards such as sound cards, faster 100 base T network adapters, SCSI adapter cards and even video editing cards. The fastest of all the adapter card ports is the AGP port, this is used to connect very hi-spec video cards that require a lot of throughput (such as textures) to be sent to and from them. Device drivers Every piece of hardware connected to a computer from printer to video cards will need a device driver to work correctly. Device drivers are used to allow the hardware and the operating system to communicate together, if there was no device driver the system would not know what or how to use the attached device. The drivers are a set of commands that tell the device they are associated with what the system is asking them to do.
In a printers case this maybe that it prints certain characters onto the paper or move the paper along to the next line. It is nice to think of the device driver as an interpreter that can speak both the languages of the operating system and that of the device it controls. The device drivers will also register the IRQ that the device needs to work correctly. Buffers A buffer is a data store shared by hardware devices or program processes that operate at different speeds or with different priorities. A buffer is a "midpoint holding place" but exists not so much to accelerate the speed of an activity as to support the co-ordination of separate activities.
The buffer allows each process or device to operate without being held up by other activities that are running at the same time. The buffers effectiveness is gauged by its size and speed of moving data into and out of it, if the buffer runs out then the process will have to be halted until the data flow resumes. So the faster the buffer is the less likely there is to be any stoppages. Buffers can be found in CD writers, this is because a constant flow of data needs to be sent to the drive to ensure there is always data to be written to the disk. When or if the buffer runs out, the writer will not have any data to write to the disk, the drive will write a large blank part on the disk, and the disk will be ruined. This is a good example of where a good quality buffer is required in order for a process to work correctly.
Interrupts: software An interrupt is a signal from a device attached to the system, this signal is used to stop what the system is currently working on and to work out what to do next. Nearly all computers are now interrupt driven, the advantage of this is that multitasking is possible. Due to the fact that a processor will just follow instructions continually and never stop unless told, it is necessary interrupt this process so that other tasks maybe performed. The switching is so fast you do not even notice it, so because of this it appears that all the programs are running at the same time. An interrupt maybe sent from a sound card when it requires a new sound to be sent to it from storage. In this case an interrupt will momentarily halt the computer and the sound will then be sent to the sound card.
Once this has occurred the previous task will then be undertaken again until another interrupt is received. There are also other software programs that aid in this, the first is called and interrupt handler. This is used to form a queuing system so that all the programs/ devices that have submitted an interrupt will have their turn in order. Also another program that aids this further is called a scheduler. A scheduler can help a program/ device with an urgent call for processor control skip the queue if it is urgent of the program has been given priority over other running. Interrupt request (IRQ): hardware An interrupt request is used like an addressing system for all hardware in the system.
Like you would expect to find your friend Paul who lives at number 5 baker street at, number 5 baker street, the computer system uses the same sort of method to find its hardware components. Each piece of hardware is given an interrupt request such as 5, this is just like Pauls address, its a location that the system can expect to find the piece of hardware it requires.
Free research essays on topics related to: device, disk drives, operating system, sound card, video cards
Research essay sample on Disk Drives Operating System
