The applet is designed to help you practice scheduling and get comfortable with the notions of task, critical path, priority list, precedence relation and task processors. Tasks and precedence relations combine into directed graphs, or digraphs. In the applet, the digraphs you build always begin with the Start vertex and follow to the End vertex. These two are always present and can't be edited out.
Under the Create Graph tab, you draw a graph by dragging the mouse. The Create Table tab offers an alternative and partly complementary way to specify the task, their durations and precedence relations. Under Practice Scheduling tab, you apply the Critical Path algorithm to the graph create under the previous tabs.
Drag the mouse to create vertices (tasks) and edges (precedence relation) of a digraph. Best begin with the Start vertex and proceed from there. The vertices created this way are assigned a name and a duration of 1. Both can be changed. The duration can be changed when the Change times box at the bottom of the applet is checked. Place the cursor at the duration you wish to change and press the left button. However remember that the applet only accommodates schedule taking 60 time units or less. Both the task name and the duration can be changed by double clicking on the node when the Create vertices and edges box is checked.
This tab shows only two buttons: Add task and Remove task. One adds to, the other removes from, the table one row. A row of the table corresponds to a task. You can edit its name, duration and the list of tasks that must precede its execution. Your activities under this tab are immediately reflected under the Create Graph tab. It may be convenient to create long vertices here and then graphically specify the precedence relations under the Create Graph tab.
The first task to accomplish under this tab is to type in a priority list. The tasks in a priority list may be separated by comma or space. This done, press the Schedule button. A little above the priority list control will appear the symbols of executed tasks and, above that, the diagrammatic representation of the scheduled task. You can press anywhere in the latter to observe below the state of the tasks at particular time during the execution of the schedule.
You can also choose the number of processors from 1 through 5. The corresponding control can be found at the the bottom of the applet. Here also you can check the Critical path box. A path will be displayed in red.