The Logical and Physical Address widgets manipulate bit strings. The strings can be divided into fields. Each field can be selected (put in the clipboard) or a value can be pasted (replaced by the value in the clipboard. Each of these is done by clicking with the mouse. Which action is performed depends on the mode that is set.
Each of the widgets has two rows of information. The top row is a set of buttons controlling the mode of the widget. The possible modes are Segment, Select, and Paste. The current mode is highlighted with a cyan background. In Figure 2, both widgets are in Segment mode. An additional Help button describes how to use the widget.
Since the contents of the logical address cannot be changed by the user, this widget does not have a Paste mode. The widget starts in the Segment mode that allows it to be divided into fields. For single level page tables, only two fields are allowed, the high order bits representing a page number and the low order bits representing the page offset. Click the mouse between two of the binary digits to segment the logical address. As you move the mouse in the logical address, the Segment button shows the sizes of the two fields that would be obtained by clicking the mouse at that time. Figure 4 shows the logical address widgets after the mouse has divided it into fields of size 18 and 12.