The tape is displayed in the bottom portion of the window. The darkened cell represents the location of the read/write head, and the '*' symbol indicates that the first cell of the tape is the cell immediately to the right. The tape extends infinitely in the rightwards direction (at least, as far as the memory limitations of the system will allow).
This guide describes how to manually write data to the tape for processing by a Turing machine.
In this program, there is only one tape, and the tape is shared with all machines that are currently open. There is only ever one read/write head on this tape, and the read/write head is shared between all machines. However, the user can manually position the read/write head and edit the tape.
Use the left and right arrow keys on the keyboard or the arrow buttons, and
, on either side of the tape
to move the head one cell at a time. You may also click on a cell to jump the read/write head to
that cell. The left-most button near the tape,
, (also available from the Tape
menu) sends the read/write head back to the very first cell.
The read/write head acts as a cursor for you to modify the tape with. Simply type the character on your keyboard to have the corresponding symbol appear on the tape in the location of the read/write head. To type a blank character, press spacebar or '_'. The backspace key also functions as you would expect it to.
Use the Open Tape ,
Save Tape and
Save Tape As items in the File menu to load and save a tape.
Often when you are debugging a Turing machine, you may wish to repeatedly apply the same tape
input to the machine. It is tedious to re-enter the tape input data manually, or repeatedly have to
select the same file to load. Hence, an option is provided to reload the tape to the state it was in when
it was last saved. If the tape has not been saved, using this option is equivalent to erasing the tape.
To reload the tape, press the Reload Tape button near the bottom
right of the window, or select
Reload Tape from the Tape Menu.
To clear the tape contents, press the Erase Tape button at the
bottom-right of the screen, or in the Tape menu. Choosing
New Tape
from the File menu also has the effect of erasing the tape.