Page 23 - slides.dvi

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a)
b)
To
Operating
i.e.
using
Time
save
register
Context
Process
Systems
the
restore
switch
—
the
context
taken
the
(with
CPU.
Processes
Context
C,
between
context
=
includes
N,
depends
Switching
context
of
V
on
idle
of
executing
executing
the
and
h/w
machine
program
that
Process A
processes,
Z
the
being
currently
flags),
OS
support.
.
counter,
.
.
environment
must:
resumed.
executing
general
Save State into PCB B
Save State into PCB A
Operating System
Restore State from PCB B
Restore State from PCB A
during
the
process
purpose
(if
idle
idle
time
Process B
executing
the
any),
registers,
and
process
is
processor
actively
status
19