I need to design a 4 bit processor that can perform the following 8 functions on R, a 4 D flip flop register that stores the internal state, and L, the literal inputs:
Arithmetic:
- W = W + L
- W = arithmetic shift left(W)
- W = W + 1
- W = W - 1
Logic:
- W = 0 (clear)
- W = W (hold)
- W = L
- W = 1's cm(W)
Implementing the functions themselves shouldn't be too much of an issue, but I'm stuck on hardware limitations... We're only allowed to use four 4 to 1 muxes, which seems to be just enough to implement either the logic or arithmetic functions but not both. I've been stuck on this all day, does anyone have any idea how I could go about this?
Arithmetic:
- W = W + L
- W = arithmetic shift left(W)
- W = W + 1
- W = W - 1
Logic:
- W = 0 (clear)
- W = W (hold)
- W = L
- W = 1's cm(W)
Implementing the functions themselves shouldn't be too much of an issue, but I'm stuck on hardware limitations... We're only allowed to use four 4 to 1 muxes, which seems to be just enough to implement either the logic or arithmetic functions but not both. I've been stuck on this all day, does anyone have any idea how I could go about this?