Level 19: Step Forward (PC+2)

Task

Connect BusConstant(2) to the PC Inc input so the PC steps by +2 instead of +1.

From level 19, the architecture switches to WORD FORMAT: each instruction takes 2 bytes (byte 0 = opcode, byte 1 = operand 0–255).

Solution

Therefore the Program Counter (PC) must step by +2, not +1.

ProgramCounter has an Inc input (port 4) — it defines how much PC increments each tick. By default, if not connected, Inc = +1.

Task: 1. Find the BusConstant on the canvas (gray block with a label). 2. Set its value to 2 (double-click the widget or mouse wheel). 3. Connect BusConstant output (Q) to the Inc input of ProgramCounter (port 4, labeled "Inc").

Now PC will step by +2, skipping even addresses: 0, 2, 4, 6… — correctly fetching word-format instructions.

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