ST ST7 - Page 209

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7 - Debugger and PROM Programmer Tutorial for ST72251
This mechanism is illustrated in the diagram below:
07-yield
PCL Task2
PCH Task2
PCL Task3
PCH Task3
PCL Task4
PCH Task4
17F (sp)
16D
15D
14D
Task1 is awaken
Active
area
of the
stack
PCL Task1
PCH Task1
17F
16F
15F
14F
The active area
of the stack is
used in each
task of this
program, to
call and return
from acana
and
timerA interrupt
routines
PCL Task3
PCH Task3
PCL Task4
PCH Task4
16F (sp)
17D
15D
14D
Task2 is woken up
Active
area
of the
stack
17F
16F
15F
14F
Yield
Permut = 0
Permut = 1
Little kernel: the Yield routine effects
(switching from task1 to task2)