Using the 7 logic sources to the left of the circuit, you can store values in the array of registers to the right.
The first three logic sources define the register to store the value in. The number is read from top to bottom. The registers in the circuit are numbered (visually) as follows:
1 5
2 6
3 7
4 8
The last four bits define the value to store in the register, again with the number read from top to bottom.
Press the button below the logic sources to store the value in the selected register.
Unfortunately, I didn't have enough room to implement reading from a register, so this only allows writing.
