In this experiment you will investigate an application of masking.

Step 1. Start SimpSim and clear the simulated machine's main memory. Place the program below in the

memory cells from address 00 to 1D. Then, place the values 6F, 87, D0, 5E, 29, and 90 in the cells from

address A0 to A5.

Address Contents Address Contents

00,01 20,80 10,11 54,34

02,03 11,A0 12,13 34,03

04,05 81,10 14,15 34,0B

06,07 B1,0C 16,17 20,A6

08,09 22,00 18,19 B4,1C

0A,0B 32,A0 1A,1B B0,00

0C,0D 23,01 1C,1D C0,00

0E,0F 14,0B

2. Run the program and record the changes in the values stored from address A0 through

A5. Assuming that the patterns represent values stored in floating-point notation, state a

general rule for determining which patterns are replaced by zeros. (Look at the sign bit of the

original patterns.)

3. Alter the program so that it replaces only the negative values with zeros and test your

program. Record the changes you made below.