The most common instruction in any CHIP-8 program just loads a constant into a register. Today you implement 6XNN, which sets VX to the byte NN, your first opcode that reads its operands.
Implement 6XNN so it sets register VX to the immediate value NN.
With the cycle loop in place, adding an instruction is now a matter of one switch arm. 6XNN is the natural first choice: “set register VX to NN.” It is how a program gets constants into registers before it can do anything with them, and it is the single most common opcode you will see in real ROMs. The high nibble is 6, x picks the register, and nn is the byte to store.
There are no flags and no edge cases here - it simply overwrites VX with NN. That makes it the clean template for the family of register instructions that follows. Because it reads both the x and nn fields you decoded last lesson, it is also the first place the fetch, decode, and dispatch pieces all work together to produce a visible change in machine state.
// inside Step's switch:case 0x6000:x := byte(op >> 8 & 0x0F)nn := byte(op & 0x00FF)v.V[x] = nnreturn nil