HD6475368CP Datasheet, PDF (44/108 Pages) Agilent(Hewlett-Packard) – H8/536 Emulator PC Interface

Using Software
Breakpoints
Note
Software breakpoints are provided with one of H8/536 undefined
opcode (1B hex) as breakpoint interrupt instruction.
When you define or enable a software breakpoint, the emulator will
replace the opcode at the software breakpoint address with the
breakpoint interrupt instruction.
When software breakpoints are enabled and emulator detects the
breakpoint interrupt instruction (1B hex), it generates a break to
background request which as with the "processor break" command.
Since the system controller knows the locations of defined software
breakpoints, it can determine whether the breakpoint interrupt
instruction (1B hex) is a software breakpoint or opcode in your target
program.
If it is a software breakpoint, execution breaks to the monitor, and the
breakpoint interrupt instruction is replaced by the original opcode. A
subsequent run or step command will execute from this address.
If it is an opcode of your target program, execution still breaks to the
monitor, and an "Undefined software breakpoint" status message is
displayed.
When software breakpoints are disabled, the emulator replaces the
breakpoint interrupt instruction with the original opcode. Up to 32
software breakpoints may be defined.
You must set software breakpoints only at memory locations which
contain instruction opcodes (not operands or data). If a software
breakpoint is set at a memory location which is not an instruction
opcode, the software breakpoint instruction will never be executed and
the break will never occur.
2-46 Getting Started