Fujitsu CM71-00101-5E User Manual

CHAPTER 4 RESET AND "EIT" PROCESSING

4.2

Basic Operations in "EIT" Processing

Interrupts, exceptions and traps are similar operations applied under partially differing
conditions. Each "EIT" event involves terminating the execution of instructions, saving
information for restarting, and branching to a designated processing program.

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Basic Operations in "EIT" Processing

The FR family device processes "EIT" events as follows.

(1) The vector table indicated by the table base register (TBR) and the number corresponding to the

particular "EIT" event are used to determine the entry address for the processing program for the
"EIT".

(2) For restarting purposes, the contents of the old program counter (PC) and the old program status (PS)

are saved to the stack area designated by the system stack pointer (SSP).

(3) After the processing flow is completed, the presence of new "EIT" sources is determined.

Figure 4.2-1 shows the operations in the "EIT" processing sequence.

Figure 4.2-1 "EIT" Processing Sequence

Note:

For a description of pipeline operations, see Section "5.1 Pipeline Operation".

Instruction at which EIT event is detected

Canceled instruction

EIT sequence

(1) Vector address calculation and new PC setting

(2) SSP update and PS save

(3) SSP update and PC save

(4) Detection of new EIT event

First instruction in EIT handler sequence (branching instruction)

Canceled instruction

ID(1) EX(1) MA(1) WB(1)

xxxx xxxx xxxx

xxxx

xxxx xxxx

ID(2) EX(2) MA(2) WB(2)

ID(3) EX(3) MA(3) WB(3)

ID(4) EX(4) MA(4) WB(4)