Building a CPU From Scratch  CS 441 Lecture, Dr. Lawlor  Circuit
Simulation via TkGate     Simple CPUs built from Digital Logic
Circuits  adder circuit  add and multiply  tri-state bus circuit
CPU with manual control    CPU with instruction decode  So
overall, this CPU's instructions look like:     <constant: 8
bits> CPU with instruction decode Here's a philosophically
similar CPU, but I'm using multiplexors instead of tristate
busses. You can get an 8-bit mux by double-clicking the mux,
clicking the "Port" tab, double-clicking on an input (or output)
pin, and typing in the bit width you want (possibly after
shuffling dialog boxes). The above CPU uses bits 7:6 as the
destination register, bit 5 is reserved, bit 4 is the arithmetic
operation, and bits 3:2 and 1:0 are both input register numbers.
So this mux-based CPU's instructions look like:     <destination
register: 2 bits>  <reserved: 1 bit> <operation: 1 bit> <source
register A: 2 bits>  <source register B: 2 bits> For example,
the instruction (hex) "13"