Figure 5 diagrams a machine layout and architecture that could be used to present programming challenges to the game player at a beginning level of play. The menu box provides the instruction set that is currently available to the player. The program area contains the instruction sequence (code), as formulated by the player by making menu selections, and then filling in the ellipses. The green arrow in the program area illustrates the program counter. The numbers box is the input source, which provides a limitless supply of input numbers, which can be drawn from any sequence desired by the framework designer. The memory shows four registers that might be available in a starting level of our architecture, and the values that these registers currently contain. The display is where program output will appear. The buttons along the bottom illustrate external commands: reset to clear the display and reset the program counter, program to allow entering or editing the instruction sequence, step to execute a single step in the program, and go to run the program automatically.
A key feature of the computing machine is that animation will be used to replicate the actions of the underlying computer architecture as a program is run. At the architectural level shown in the figure, when the player presses the go button the animation will show how the program counter progresses through each instruction, the changes in the register values, and the generation of the output shown on the display. Data flow through the machine will be indicated by the green ``funnels'' under the the numbers and memory boxes. These will be positioned over or under the appropriate memory register whenever an input or an output instruction is executed. Using visual techniques like this, the game designer can provide a representation of what happens inside the computer during instruction execution, and reinforce a cognitive model that is appropriate for the current level of play. As the player progresses through levels, the machine architecture will become more complex, and the animation will be appropriately adjusted.