The single-cycle data path uses a total of 9 data path control bits. Two of the bits are MemRead and MemWrite which control whether a read from the data memory or a write to the data memory is performed. Suppose that the number of data path control bits is reduced to only 8 bits by substituting a single bit, Memctl, in place of the MemRead & MemWrite pair. The default value for Memctl is 0, which means read from the data memory. Memctl = 1 means write to the data memory. Explain how making this substitution affects each of the following instructions:

add $9, $8, $7

sw $4,16($2)

beq $3, $11, exit ; the label exit corresponds to address 0x400BD000