• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Input Output Functions of an Operating System

Extracts from this document...

Introduction

Ricki Lambert Operating Systems Assignment 2 Input Output Subsystem Introduction An operating system is the device used to communicate with all input and output devices. For example this may be a keyboard or mouse, things of this nature. This process is controlled by a virtual layer which is known as a application input output interface. It is this device that ensures every input output device under goes a buffering and scheduling process. From here the operating system can communicate with the processor in order for the hardware device to be controlled / managed. There are four main functions that assist with this processor communications and they are as follows; 1. Input output instructions vs. memory mapped. - This is where information is sent in order for the process to be logged in to its own memory location within a register. 2. Input output hardware device - At this stage the operating system will check whether it has to read the device or write to it. 3. Polled vs. interrupt driven - Modern operating systems use interrupt driven methods in preference to its counterpart. ...read more.

Middle

be issued in to the status register * The device can see the command is ready and from here is sets the device to busy * It is now enabled to perform the writing operation It is when the above is complete that the cycle can begin again for a new set of instructions. More complex processors use the interrupt driven method and are capable of the following tasks; * At the end of each instruction it checks for further interrupts that maybe pending * It will save the programme counter * Saves the processor status * It can change the processors mode * It will jump to the well known address Interrupt Driven I/O - Data is entered form a keyboard and stored in the memory so the instruction is to write. This is then placed in to the instruction register but the actual data itself will be placed in the data register. The CPU will then receive this and send the data from the register to its desired destination. The instructions are stored in to the intermediate buffer. ...read more.

Conclusion

They are single buffering, double buffering and circular buffering. A singular buffer is used store data between the input and output device and user process. There is a double buffer which has twice the holding capacity and a circle buffer which holds many more commands. This allows less CPU waiting which ensures a better and more efficient system. This form of CPU management can then be broken down into input output issues. Caching: Caching is the form of fast memory holding copied of data (normally the data held in the data buffer). It can work with both read and write and it is key to input output performance. Scheduling: Operating systems try to invoke fairness when switching between input and output properties. This is similar to the scheduling technique. Spooling: Spooling is the form of control used by singular input/output devices. It can queue commands for example a printer, by storing them in the spooling area. Error Handling: It has input output error checking properties; it can recover from a disk read error, when the device is unavailable and such possibilities. The system often records errors in a log on the operating system. Device Reservation: It can use system calls for specific duties when needing exclusive access to a device. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Computer Science section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Computer Science essays

  1. Marked by a teacher

    The systems development life cycle (SDLC) is a conceptual model used in project management ...

    3 star(s)

    come up after its practical use starts, so the issues related to the system are solved after deployment of the system. Not all the problems come in picture directly but they arise time to time and needs to be solved; hence this process is referred as Maintenance.

  2. Free essay

    Hardware and Functions of a Micro Processor

    If this condition is not met then the output will be a low voltage. This can be represented in a truth table which can be seen below; Input A Input B Output 0 0 0 0 1 0 1 0 0 1 1 1 * OR - The OR gate

  1. Programming Techniques

    These are brief messages that help to remind the programmer what a particular line or section means when returning to it later. A special symbol is used to tell the compiler to ignore the comment line. Comments are not translated, so take up no space in the final compiled program.

  2. Security Issues of E-Commerce

    But why these two pieces of software. Well the fact that theses viruses and spy ware can trace your every move and copy all the details you enter in to your machine we can see that if using the computer for e-commerce or online banking that there is a massive security risk.

  1. Smart Card System

    Triple DES is a product cipher, which like DES, operates on 64-bit data blocks. There are several forms, each of which uses the DES cipher 3 times. Some forms use two 56-bit keys and some use three. The DES "modes of operation'' may also be used with triple-DES.

  2. Input & output devices.

    In most cases the data will be read by the document ready and stored on magnetic tape or disc ready for batch processing. Optical Mark Reading (OMR) Here the marks are detected optically measuring reflected light. The readers use CLOCK MARKS to determine which areas of the card to read, so the cards can vary in size and in format.

  1. Statistics - How good are people's memory considering different factors?

    I will then make the students do memory tests and according to which year they are in, divide the results and compare them in methods that are relevant. I will then check in which Year are pupils' memory the strongest and in which Year it is weakest.

  2. Processor Scheduling

    First Come First Served (Also known as First in First out F.I.F.O) This method makes the processor process in order of arrival. It can be a very slow method of processing due to the illogical order. The average speed of processing can be minimised when processing in the reverse order.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work