A student is debugging his program. His program does not have access to

memory locations x$0000$ to x$2$FFF$.$ Why that is the case we will discuss

before the end of the book. The term is $$privileged memory$$ but not

something for you to worry about today.

Exercises $227$

He sets a breakpoint at x$3050,$ and then starts executing the program.

When the program stops, he examines the contents of several memory

locations and registers, then hits single step. The simulator executes

one instruction and then stops. He again examines the contents of the

memory locations and registers. They are as follows:

Before After

PC x$3050$ x$3051$

R$0$ x$2$F$5$F xFFFF

R$1$ x$4200$ x$4200$

R$2$ x$0123$ x$0123$

R$3$ x$2323$ x$2323$

R$4$ x$0010$ x$0010$

R$5$ x$0000$ x$0000$

R$6$ x$1000$ x$1000$

R$7$ x$0522$ x$0522$

M$[$x$3050]$ x$6???$ x$6???$

M$[$x$4200]$ x$5555$ x$5555$

M$[$x$4201]$ xFFFF xFFFF