Music, a download and a video call
You play music, download a game and chat on video, all at once. You have one processor. It seems to do three things at the same moment. Is it cheating?
Yes, a little. The trick is in the main program that runs the computer. Today you find out how it works, and why some computers need a different trick.
Key words
| Word | What it means | Example |
|---|---|---|
| Operating system | the main program that runs the computer and shares its parts | |
| Batch | a group of jobs run one after another with no user | overnight payroll |
| Multitasking | running many tasks so they seem to run together | |
| Time-slicing | giving each task a short turn on the CPU | |
| Interrupt | a signal that makes the CPU stop and deal with something urgent | a key press |
| Real-time | must answer within a fixed, very short time | |
| CPU | the processor that runs program instructions | |
| Scheduling | choosing which job runs and when |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can describe batch, multitasking and real-time operating systems and say when each is used.
Starter
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Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Batch systems run jobs with no user
A batch system collects jobs and runs them later, one after another, with nobody watching. Nothing asks the user a question while a job runs. That is called non-interactive.
It suits a huge amount of the same work, such as printing 50,000 bank statements overnight. Scheduling decides the order and the start time, so the machine is busy at quiet hours.
Batch processing at a glance
| Feature | What it means | Example |
|---|---|---|
| Non-interactive | No user input while it runs | A payroll run |
| High volume | A large amount of similar work | 50,000 statements |
| Scheduling | Jobs are queued and started at set times | Starts at 2 am |
The cells students fill in are left blank in this preview.
Check
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Check
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.