Breaking Into The Monitor; Using Software Breakpoints - HP 7700 Series User Manual

Note
Breaking into the
Monitor
Using Software
Breakpoints
Note
2-20 Getting Started
Modifying/displaying internal RAM or SFR suspends user program
execution. This is because the emulator uses internal RAM and SFR of
emulation processor to perform emulation. However, you can
configure the emulator so that write cycles are performed to both
internal RAM (or SFR) and emulation memory. If you do this, you can
display the data written to emulation memory without suspending user
program execution. Refer to chapter 4 and chapter 5 of this manual for
more details.
The "break" command allows you to divert emulator execution from
the user program to the monitor. You can continue user program
execution with the "run" command. To break emulator execution from
the sample program to the monitor, enter the following command.
break <RETURN>
Software breakpoints are provided with an 7700 Series BRK
instruction. When you define or enable a software breakpoint, the
emulator will replace the opcode at the software breakpoint address
with a BRK instruction.
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.