During my time at Waseda university my friend David was (and probably still is) a big Minecraft fan.

This is a simple 8 bit Arithmetic Logic Unit (ALU) that was built using XOR, OR, AND, NOT gates and a multiplexor implemented using ‘redstone circuit’ objects in the game ‘Minecraft’. The unit was able to do simple arithmetic and logical operations on two 8-bit input values by selecting the appropriate Op-codes.

Above is a high level overview of the whole system, main parts are labelled with a number.

  1. The 'control room' where two 8 bit values are input using in-game 'levers' (on for 1 off for 0), op-codes can be selected using levers and the output is displayed as in game 'lamps'.

  2. The 8 white buses carrying the input from the control room to the rest of the system, the red and yellow lines you see carry the op-codes which decides where the input will be directed.

  3. The area where logical operations can be performed on the input.

  4. The area where addition and subtraction can be performed on the input.

  5. The green buses that carry the output back to the control room

Fig. 1 The different isolated gates, from top left, AND, XOR, OR, NOT gates and a multiplexer.
Fig. 2 An isolated adder/subtractor unit with carry in/carry out
Fig. 3 The input levers, view from bus 1 (most significant bit). The bottom is the first 8 bit input (labelled A). The top the second.
Fig. 4 The Op-code levers with associated op-code table
Fig. 5 A night time view

If you have Minecraft and would like to take a look around for yourself, you can find the world file here

Many thanks to David Doludda who between ourselves have spent too many hours in this game.