Motorola MVME162LX 사용자 설명서

Preserving the Debugger Operating Environment

4-15

Notice in the preceding example that the value of the target stack 
pointer register (A7) has not changed even though a trace exception 
has taken place. Your program may either use the exception vector 
table provided by 162Bug or it may create a separate exception 
vector table of its own. The two following sections detail these two 
methods. 

The 162Bug initializes and maintains a vector table area for target 
programs. A target program is any program started by the bug:

❏

Manually with the 

 command

❏

Manually with trace commands (

, 

, or 

)

❏

Automatically with the 

 command. 

The start address of this target vector table area is the base address 
($00) of the debugger memory. This address is loaded into the 
target-state VBR at power-up and cold-start reset and can be 
observed by using the 

 command to display the target-state 

registers immediately after power-up. 

The 162Bug initializes the target vector table with the debugger 
vectors listed in 

 and fills the other vector 

locations with the address of a generalized exception handler. The 
target program may take over as many vectors as desired by simply 
writing its own exception vectors into the table. If the vector 
locations listed in 

debugger functions are lost. 

The 162Bug maintains a separate vector table for its own use. In 
general, you do not have to be aware of the existence of the 
debugger vector table. It is completely transparent and you should 
never make any modifications to the vectors that it contains.