The x04 Proccessor and ISA
The x04 Processor is a virtual, theoretical CPU which has a 4 bit data width.
Where can I find this?
If you haven't read already, it is not real. It has been constructed in Minecraft however.
Each instruction takes up 1 byte. One half is the opcode, the other is for specifying numbers to load into registers or for addressing memory.
Here are some opcodes.
0100 - Loads the next nibble into A
0110 - Loads the next nibble into B
0001 - Adds A and B and saves the answer to register O
1001 - Copies register O into the specified memory location