EIT
4.1 Outline of EIT
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4.1 Outline of EIT
If some event occurs when the CPU is executing an ordinary program, it may become necessary to suspend the
program being executed and execute another program. Events like this one are referred to by a generic name as
EIT (Exception, Interrupt and Trap).
(1) Exception
This is an event related to the context being executed. It is generated by an error or violation during instruction
execution. This type of event includes Address Exception (AE), Reserved Instruction Exception (RIE) and Floating-
Point Exception (FPE).
(2) Interrupt
This is an event generated irrespective of the context being executed. It is generated by a hardware-derived signal
from an external source, as well as by the internal peripheral I/O. This type of event includes Reset Interrupt (RI),
System Break Interrupt (SBI) and External Interrupt (EI).
(3) Trap
This refers to a software interrupt generated by executing a TRAP instruction. This type of event is intentionally
generated in a program as in the OS’s system call by the programmer.
EIT
Exception (Exception)
Interrupt (Interrupt)
Reserved Instruction Exception (RIE)
Address Exception (AE)
Floating-Point Exception (FPE)
Reset Interrupt (RI)
System Break Interrupt (SBI)
External Interrupt (EI)
Trap (Trap)
Trap (TRAP)
Figure 4.1.1 Classification of EITs
32180 Group User’s Manual (Rev.1.0)
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