© Thomas Kunz 2000
SCE 574
180
Processes and
Interrupt Handling Implementation
äTo implement processes the OS maintains a process table
äExamples of
important information in the table
Process management Memory management File Management
Registers
Pointers to segments
Root directory
Program counter
Process id
Working directory
Stack pointer
Exit status
File descriptors
Process start time
.... ....
CPU time used
Message queue pointers
äInterrupt handling
is accomplished as follows
1. Interrupt: hardware stacks program counter, etc.. of current
program
2. Hardware loads new program counter from interrupt vector (table)
3. Assembly language routine saves registers in process table
(above)
4. Assembly language routine procedures sets up new stack for C
handler
5. C procedure marks interrupt service process as ready in the above
table
6. Scheduler decides which process to run next (choose highest
priority)
7. C procedure returns to assembly code
8. Assembly languages procedure starts up next process
Uses the interrupt
number
We implement
most things in
a high level
language