Managing security, hardware and processes

By the end of this lesson

By the end you can explain security management, hardware management and process management, and say what each one actually does.

Security management

The OS is the bouncer. Security management means checking who is allowed to do what, and stopping everything else.

The tasks:

Authentication: usernames and passwords, PINs, biometrics — proving who you are before anything else happens.
Authorisation: deciding what an authenticated user may access (this file, that printer), through access rights and permissions.
Protecting files and memory from other users and other processes.
Logging activity, so suspicious behaviour can be traced.
Providing the mechanisms that malware protection uses (a virus checker is separate software that relies on them).

A useful exam sentence: the OS authenticates users and enforces access rights, so one user cannot read or change another user's files.

Hardware management is the OS controlling the input, output and storage devices attached to the machine.

The tasks:

Communicating with devices through device drivers — small programs that know how a particular printer or graphics card works.
Allocating devices to processes, so two programs do not send print jobs to the same printer at once.
Buffering and spooling: data is held (in a buffer in memory, or on disk in a spool queue) while a slow device catches up, so the processor is not kept waiting.
Handling interrupts: when a device signals that it has finished, the OS decides what happens next.
Managing device settings such as power, brightness and resolution.

A process is a program that is running (or ready to run). Process management is the OS deciding which process uses the processor, and when.

The tasks:

Creating and terminating processes when programs start and close.
Scheduling: choosing the next process to run, using a policy such as round-robin.
Multitasking: switching rapidly between processes so they appear to run at the same time.
Managing states: a process is running, ready (waiting for the processor) or blocked (waiting for input or a device).
Handling interrupts and priorities, so a high-priority task such as a keystroke is dealt with promptly.

The scheduler moves processes between running, ready and blocked.

Worked example: Worked example: what happens when you print

You press Ctrl+P in a word processor. Trace the OS's management tasks.

Have a go first?

Quick check

Multiple choiceQuestion 1 · Recall

Multiple choiceQuestion 2 · Apply

Multiple choiceQuestion 3 · Apply

Answer the 3 questions above to continue.