2 Bits, 256 Bytes

2 Bits, 256 Bytes is simply 2 Bits, 1 Byte by User:Gilbert189 but now, the 1 byte limit is now 256 bytes.
The only major difference is that the END instruction will only end the program if it is the end of the code.
This allows this:

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

Output:

mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm