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Chapter 4: Viewing Code and Data
Displaying Program Context
The information displayed in the register window varies with different
microprocessors. See the "Registers" chapter and page 143 for information
about the registers and pseudoregisters which you can display using expression
commands.
Stack Pointer. A7 is the stack pointer (SP) for the current mode (user,
supervisor, or interrupt). The stack pointers (USP, ISP, and MSP) that are not
current are labeled and displayed separately.
Previous Instruction Pseudoregister @pi. The program counter for the
previous instruction is indicated by the pseudoregister @pi. This value is
useful for finding the instruction that jumped to, called, or returned to the
current location.
PC and @pi are truncated to show only the address bits valid for the current
CPU type.
Cycle Count Pseudoregister @cycles. The number of cycles (@cycles)
used by instructions since this counter was last cleared (by the command
Memory Register @cycles = 0, for example) is displayed as the pseudoregister
@cycles.
Exception Handling Keyword @exc. The value of the pseudoregister @exc
determines how the debugger handles exceptions. See the chapter titled "CPU
Simulation" in this manual a detailed explanation of this keyword.
Access Status Pseudoregister @as. The pseudoregister @as is the access
status used by the processor's CAL L M and RTM instructions. It is used to
determine the legality of as access level change.
CPU Modes and Registers Some registers in the display are shown only for
some CPU modes, as shown in the following table.
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