The P6502 simulator provides for a 48 cell I/O window arranged in a 40 row x 12 column grid. User can output data to be displayed anywhere in the window. Additionally, text entered directly into the window from the keyboard can be read. Access and control to the window is performed via a set of I/O ports starting at $e000. This location can be changed under the P6502 menu choice: Simulator/Options/Simulator On the right, find In/out memory area, locate the "Start addr:" input box listing the current starting port address. Make sure the Active box is checked. Port usage: (w) write only, (r) read only, (rw) read or write $e000 ; (w) writing any value to this port causes the window to be cleared. $e001 ; (w) writing a byte to this port will cause the character to be output to the current cursor location on I/O window. The (#$0d) character will be interpreted to move the cursor back to the beginning of the current line. Also, the backspace (#$09) character is correctly handled. $e002 ; (w) writing a byte to this port will cause its decimal value to be output at the current cursor position. and will be translated. $e003 ; (w) writing a byte to this port will cause its hexadecimal value to be output at the current cursor position. and will be translated. $e004 ; (r) reading from this port address will retrieve a value typed in the I/O window. Remember to first click on the In/Out Window to make it active before entering anything from the keyboard. $e005 ; (r/w) indicates current column location where I/O will occur. $e006 ; (r/w) indicates current row location where I/O will occur.