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79
CHAPTER 3 INTERRUPTS
3.8 Operation Flow of and Procedure for Using the Extended
Intelligent I/O Service (EI
2
OS)
Figure 3.8-1 is a diagram of the EI
2
OS operation flow. Figure 3.8-2 is a diagram of the
EI
2
OS use procedure.
■ EI
2
OS Operation Flow
Figure 3.8-1 EI
2
OS Operation Flow
ISE = 1
DIR = 1
BF = 0
SE = 1
DCT = 00
IF = 0
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
YES
NO
Interrupt request issued
from internal resource
Reading ISD/ISCS
Interrupt sequence
End request from resource
Data indicated by IOA
(Data transfer)
Memory indicated by BAP
Data indicated by BAP
(Data transfer)
Memory indicated by IOA
Update value
depends on BW.
Update value
depends on BW.
Updating IOA
Updating BAP
Decrementing DCT
Setting S1 and S0
to "00"
Clearing resource
interrupt request
CPU operation return
Setting S1 and S0
to "01"
Clearing ISE to "0"
Interrupt sequence
⇓
⇓
BAP : Buffer address pointer
I/OA
: I/O address pointer
ISD
:EI
2
OS descripter
ISCS : EI
2
OS status
DCT : Data counter
ISE : EI
2
OS enable bit
S1 and S0: EI
2
OS end status
Setting S1 and S0
to "11"