Long description

There are three vertical blocks from left to right labeled C P U 1, Memory, and C P U 2. All are connected via a common bus. The memory block is highlighted and has a horizontal rectangular block labeled Word 1000 is initially 0. There are four steps shown in this diagram. The first step with a forward arrow from C P U 1 points to a rectangular block in Memory labeled 1. C P U 1 reads a 0. The second step with a backward arrow from C P U 2 points to a rectangular block in Memory labeled 2. C P U 2 reads a 0. The third step with a forward arrow from C P U 1 points to a rectangular block in Memory labeled 3. C P U 1 writes a 1. The fourth step with a backward arrow from C P U 2 points to a rectangular block in Memory labeled 4. C P U 2 writes a 1.