Assuming that you are talking about xxx86 CPU, you can insert the
breakpoint into the actual (or simulated) address as a byte operand. OXC3
seems to come to mind (that is a one-byte RET instruction). The clever bit
is what you do to restore the original code when you reach the breakpoint.
The ret instruction fills the bill because it pops the return address off
the stack and allows you to implement a standard procedure at that point.

Best Wishes,
Bill.

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