Case Study #6

Name: Willy T. Pedroso
Section: BSIT 3 Day
Case Study #: 6


A process can be thought of as a program in execution. A process will need
certain resources — such as CPU time, memory, files, and I/O devices — to
accomplish its task. These resources are allocated to the process either when it is
created, or while it is executing.
As a process executes, it changes state. The state of a process is defined in
part by the current activity of that process. Each process may be in one of the
following states:
New State: The process being created.
Running State: A process is said to be running if it has the CPU, that is,
process actually using the CPU at that particular instant.
Blocked (or waiting) State: A process is said to be blocked if it is waiting
for some event to happen such that as an I/O completion before it can
proceed. Note that a process is unable to run until some external event
happens.
Ready State: A process is said to be ready if it is waiting to be assigned to a
processor.
Terminated state: The process has finished execution.
Logically, the 'Running' and 'Ready' states are similar. In both cases the process is
willing to run, only in the case of 'Ready' state, there is temporarily no CPU
available for it. The 'Blocked' state is different from the 'Running' and 'Ready'
states in that the process cannot run, even if the CPU is available.





From the READY state to the WAITING state.
A job in the WAITING state is waiting for peripheral device response which must be received before the CPU can effectively be used again. A process in the READY queue is ready in all aspects to make effective use of the CPU. If a job in the READY state cannot proceed because a required device fails, it should be sent back to the HOLD state, not the WAITING state.

From the WAITING state to the RUNNING state.
The Process Scheduler selects processes from the READY state for the CPU. Bypassing the READY queue would make process management impossible.