Editing Programs - Commodore VIC-20 Programmer's Reference Manual

EDITING PROGRAMS
CURSOR CONTROLS
One of the most important features of the VIC is the ability to
move the cursor around the screen and make changes to program
lines. This is called "screen editing." The VIC will allow cursor
movement around the screen in any direction, inserting extra
spaces into a tine, and erasing unwanted characters. The VIC's
editor is one of the most powel1ul and easy to use of any computer.
There are 6 keys on the keyboard that are used for editing. These
arethel!llIl!HI.
~.
1iIII. and the_
bar. These are all dual purpose keys, with different actions
when the
Ella
or
~
keys
are pressed.
The
!HI,
~,
II
,and _ will all repeat
if
held down for at
least a second .
•••
When unshifted, this moves the cursor to the upper left corner of
the screen, called the "home position:'
With the _ (or
~
key) held down, this key will
erase everything on the
scree~
and move the cursor to the home
position. This does not erase a program, variables, or anything else
currently in memory.
b.1I
Without the
Ella,
this key serves to delete the character to
the left of the cursor. Anything else on the line to the right of the
de~
leted character is moved one space to the left, filling in the gap.
With the
Ella,
this becomes an insert key. A space is cre-
ated at the cursor's position, and everything else on the line to the
right of the cursor is moved one more space to the right. If this
pushes the last character on the line past the right end of the line, all
lines below the current one are pushed down one line. Once the
line is filled all the way to the end of 4 screen lines (88 characters),
this key has no effect. (See also QUOTE MODE.)
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