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Principles of Operating Systems
Notes
Figure 2.2: Process Control Block (PCB)
P
P
P
R
M
L
Process state: The state may be new, ready, running, waiting, halted, and so on.
Program counter: The counter indicates the address of the next instruction to be executed
for this process.
CPU registers: The registers vary in number and type, depending on the computer
architecture. They include accumulators, index registers, stack pointers, and general-purpose
registers, plus any condition-code information.
Along with the program counter, this state information must be saved when an interrupt
occurs, to allow the process to be continued correctly afterward (Figure 2.3).
CPU-scheduling information: This information includes a process priority, pointers to
scheduling queues, and any other scheduling parameters. Memory-management information:
This information may include such information as the value of the base and limit registers,
the page tables, or the segment tables, depending on the memory system used by the
operating system.
Memory-management information: This information may include such information as the
value of the base and limit registers, the page tables, or the segment tables, depending on
the memory system used by the operating system.
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