Here is a little more optimized code for the scroll up:

Code:
temp_byte = sutun_reg[i]
temp_Byte = temp_Byte << 1
temp_Byte.0 = STATUS.0
sutun_reg[i] = temp_byte
It get's rid of the bit variable by taking advantage of the fact that the underlying assembly instruction moves the MSbit from the left shift into the "C" bit (which is bit 0) of the "STATUS" register.

This will also work in a similar way for scrolling down:

Code:
temp_byte = sutun_reg[i]
temp_Byte = temp_Byte >> 1
temp_Byte.7= STATUS.0
sutun_reg[i] = temp_byte