EDP-I General Operation
The EDP-I interfaces to the industry standard “AT” style keyboard using a PS/2 sized connector
and provides a ‘line’ based editor. This allows users to enter/edit one line without disturbing
other lines on the display. The exceptions to this are:
The cursor will wrap-around to the next line when typing text; reaching the last space on
the last line will move the cursor to the first space of the first line.
The backspace key will also wrap around to the line above when reaching the start of the
line. If on the first line, it will wrap around to the last space on the last line.
The following functions are supported:
All alphabetic characters and punctuation characters are displayed as they are typed in.
arrow keys:
moves the cursor in the direction of the arrow.
auxiliary key pad:
as selected by the ‘num lock’ key.
Enter
Pressing either enter key will move the cursor to the start of the next line.
If the cursor is on the last line of the display, it will be moved to the top,
left corner.
Tab:
The ‘tab’ key will center the cursor in the middle of the current line.
End:
Moves the cursor to the right of last character of the current line . If the
line is full, it will be moved to the last space.
Home:
Moves the cursor to the start of the current line.
Page up:
Moves cursor to the top of the display.
Page down:
Moves the cursor to the bottom of the display.
Insert:
Pressing the ‘insert’ key will toggle between the ‘insert’ mode and the
‘overwrite’ mode. In the insert mode, typed characters will be inserted to
the left of the cursor and characters to the right will be shifted right. The
last character on the line will be discarded. During the insert mode, the
cursor will be displayed as an ‘
_
’. During ‘overwrite’ mode, the cursor will
be a solid box ‘
#
’.
Delete
As expected, the delete key will delete the character at the current cursor
location. Characters to the right of the cursor on the current line are shifted
to the left.
Backspace
Deletes the character to the left of the cursor and shifts the cursor one space
to the left. Does not affect characters to the right. If it reaches the end of a
line it will move up one line and continue deleting. If it reaches the top left
corner it will move to the bottom right.
^C
Pressing both the left control key and the ‘c’ character will clear the screen
and move the cursor to 0,0.
