Motorola MVME162 User Manual

Using the 162Bug Debugger

4-12

Example: Trace one instruction using debugger.

162Bug>

PC   =00010000 SR   =2700=TR:OFF_S._7_.....  VBR  =00000000

USP  =0000DFFC MSP  =0000EFFC ISP* =0000FFFC SFC  =0=F0

DFC  =0=F0     CACR =0=........

D0   =00000000 D1   =00000000 D2   =00000000 D3   =00000000

D4   =00000000 D5   =00000000 D6   =00000000 D7   =00000000

A0   =00000000 A1   =00000000 A2   =00000000 A3   =00000000

A4   =00000000 A5   =00000000 A6   =00000000 A7   =0000FFFC

00010000 203C0000 0001    MOVE.L     #$1,D0

162Bug>

PC   =00010006 SR   =2700=TR:OFF_S._7_.....  VBR  =00000000

USP  =0000DFFC MSP  =0000EFFC ISP* =0000FFFC SFC  =0=F0

DFC  =0=F0     CACR =0=........

D0   =00000001 D1   =00000000 D2   =00000000 D3   =00000000

D4   =00000000 D5   =00000000 D6   =00000000 D7   =00000000

A0   =00000000 A1   =00000000 A2   =00000000 A3   =00000000

A4   =00000000 A5   =00000000 A6   =00000000 A7   =0000FFFC

00010006 D280             ADD.L      D0,D1

162Bug>

Notice 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, either manually with GO 
or TR type commands or automatically with the BO command. The start 
address of this target vector table area is the base address 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 RD command to display the 
target-state registers immediately after power up.