PPT Slide
One you are in the trace mode, hitting return executes one instruction and displays the registers.
PC=00040E SR=2000 SS=00A00000 US=00000000 X=0
A0=00000000 A1=00000000 A2=00000000 A3=00000000 N=0
A4=00000000 A5=00000000 A6=00000000 A7=00A00000 Z=0
D0=00000025 D1=0000005C D2=00000000 D3=00000000 V=0
D4=00000000 D5=00000000 D6=00000000 D7=00000000 C=0
---------->MOVE.B D1,$1002
The next instruction to be executed is MOVE.B D1,R.
The previous instruction was ADD.B D0,D1. The values $25 and $37 are added to give $5C which is put in D1.