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If "D" is entered alone on a line, the missing address defaults to zero. Since
altering address zero is not permitted, the message
Cannot edit memory in this area
is displayed.
5.4
Go (Run Program)
The command is
G [addr]
Any set breakpoint is activated, and control passes to the test program. Reg-
isters will be loaded with the values shown by a "Display / Set Register" com-
mand.
NB When the debugger starts up, all test-program registers, including PC and
SP, default to zero. It is the user's responsibility to load meaningful values in
these registers, before executing code.
It is legal to start with SP=0: the stack will grow downward from FFFF.
5.5
Trace instructions
The "N" ("next") command permits program instructions to be traced through
automatically. Entering "N" alone will cause one instruction to be executed,
before control returns to the debugger. If a count is entered, that number of
instructions will be executed before the debugger regains control. After each
instruction is executed, the resulting register-values are displayed (as for the
"Display / Set Registers" command below).
Caution: Tracing under the "N" command runs the target program much slower
than real-time execution. There are also significant lengths of interrupt-disabled
code, and the execution environment constantly switches between the user pro-
gram and the debugger (which allocates its own stack space). This command
should not be used to test time-critical code segments.
The TRACE function temporarily stores an EI instruction at the location before
the instruction being traced. This location must be writeable, or the command
will be refused. For example, you cannot TRACE an instruction at location
8000H, since the preceding location, 7FFFH, is in ROM, and the EI cannot be
stored.
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