Interrupts

A cpu processes things one at a time.

An interrupt is where a CPU compares multiple tasks to see which has the biggest priority. It then start the most important task before moving on to anything else.


Interrupts are recorded in the interrupt register.

An example of an interrupt would be: if music is playing but then the user opens PowerPoint, the computer will prioritise opening powerpoint and then quickly switch back to the music (all without the user knowing).


Interrupts are used in a computer system to prevent the computer system for slowing down and any data loss.

The main types of interrupts:







Comments

Post a Comment

Popular posts from this blog

CPU Fetch-Decode-Execute Cycle

Image
A CPU (central processing unit) executes and manages the rest of the hardware inside a computer system - it is the brain of a computer! The CPU is made up of the main memory, the processor and the cache memory. It's job is to process data (by processing we mean searching, sorting, calculating and decision making). The CPU follows the Fetch-Decode-Execute cycle. The Fetch Stage: the CPU use a piece of hardware called the ' address bus ', this is where the CPU asks the RAM for some data. The RAM then responds with this data on the ' Data Bus '.  The Decode Stage: This is where the CPU converts the instructions in to a way in which it understands it. It then gets things ready for the next step.  The Execute Stage: This is where data processing happens. Instructions are carried out on the data, as soon as the command is completed it starts the next one. 
Read more

OSI Network Model

Open Systems Interconnection (OSI) model - a conceptual framework that describes the functions of a networking or telecommunication system. The OSI model has 7 layers.  Layer 7 - Application Layer This is what the user communicates with. It is the applications that we used - Google Chrome & Skype are examples.  Layer 6 - Presentation  This is where data is converted from the application framework into something that the network understand. The data would be encrypted here for example.  Layer 5 - Session Computer need to create a session between the two devices so they can speak to each other. This is done here. The computer communicate telling each other how much time they should wait for a response from each other and what they should do when the task has been completed (end session) etc.  Layer 4 - Transport  The Transport Layer deals with the coordination of the data transfer between end systems and hosts. This...
Read more

Scheduling

Image
Scheduling is where a computer prioritises tasks to be carried out in a certain order to maximise the use of the computer and all of its peripherals. The algorithm must be robust so the computer does not freeze and also so every task/user gets a fair response time. Two main types of jobs are I/O bound jobs and processor bound jobs: I/O bound jobs (input/output) examples: Sending a document to the printer. Moving the mouse. Typing on the keyboard. Processor bound jobs examples: Playing Music Watching a video Calculating in Excel. There are different ways a processor can prioritise tasks: FCFS (first come first served) - tasks are started and completed in the order they are received. RR (round robin) – the time slice is 1 minute - each job has a minute spent on it before moving onto the next one. This occurs in a circuit until all jobs are complete. SJF – shortest job first - The job with the shortest completion time is carri...
Read more