and we've connected them all to the bus here,

really the only piece left to do is build the control logic

which is really the brains of the CPU.

And so if we look at what we've built so far we've go the central bus here

and then we've got all these modules connected to it

so there's the memory address register, the RAM, the instruction register, program counter,

the A and B registers which feed into the arithmetic and logic unit

which will either add or subtract the values in the A and B register

and then the output register which connects to the display.