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CHAPTER 3 INTERRUPTS
Figure 3.1-3 Overview of the Extended Intelligent I/O Service (EI
CPU
■ Exceptions
Exception processing is basically the same as interrupt processing. When an exception is detected between
instructions, exception processing is performed. In general, exception processing occurs as a result of an
unexpected operation. Therefore, use exception processing only for debugging programs or for activating
recovery software in an emergency.
56
Memory space
by IOA
I/O register
➂
ISD
➂
by BAP
➃
Buffer
I/O register
Interrupt request
by ICS
➁
Interrupt control register
Interrupt controller
➀ I/O requests transfer.
➁ The interrupt controller selects the
descriptor.
➂ The transfer source and destination
are read from the descriptor.
by DCT
➃ Data is transferred between I/O and
memory.
2
OS)
Peripheral
➀
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