2bit CPU using relays.
If 1bit CPU is not enough for you, try this 2bit CPU.
The top left switch group is ROM, with addresses 00, 01, 10, and 11 from the top.
The left two digits are instructions and the right two digits are Im.
The lamps are PC, A Reg, and B Reg (Output) from the top.
There are only 4 instructions as follows
00 LD A, Im
01 LD B, A
10 ADD A, Im
11 JMP Im
The following program is written as an example.
1001 ADD A, 01
1001 ADD A, 01
1001 ADD A, 01
0100 LD B, A
The operation is to add 1 to Register A, save it in Register B after 3 additions, and repeat this operation.
After this 2bit CPU, I would like to move on to 4bit CPU, but there doesn't seem to be enough space (as usual)...
