Breakpoint Instruction Flowchart - Motorola MC68020 User Manual

PIPE STAGE D
EXECUTE INSTRUCTION WORD
Group/
Priority Exception and Relative Priority
0 0.0—Reset
1 1.0—Address Error
1.1—Bus Error
2 2.0—BKPT, CALLM, CHK, CHK2,
cp Midinstruction, cp Protocol Violation,
cpTRAPcc, Divide by Zero, RTE, RTM,
TRAP, TRAPcc, TRAPV
3 3.0—Illegal Instruction, Line A, Unimplemented
Line F, Privilege Violation, cp Preinstruction
4 4.0—cp Postinstruction
4.1—Trace
4.2—Interrupt
NOTE: 0.0 is the highest priority; 4.2 is the lowest.
MOTOROLA
A4–A2
CYCLE TERMINATED WITH
DSACK1/DSACK0
INSTRUCTION WORD ON DATA BUS
EXIT
Figure 6-6. Breakpoint Instruction Flowchart
Table 6-4. Exception Priority Groups
M68020 USER'S MANUAL
ENTRY
A19–A16 $0
BREAKPOINT NUMBER
INITIATE READ BUS CYCLE
CYCLE TERMINATED WITH
BERR
Aborts all processing (instruction or exception) and
does not save old context.
Suspends processing (instruction or exception) and
saves internal context.
Exception processing is part of instruction execution.
Exception processing begins before instruction is
executed.
Exception processing begins when current instruction
or previous exception processing has completed.
TAKE ILLEGAL INSTRUCTION
EXCEPTION
Characteristic
6- 19