Click above to get retro games delivered to your door ever month!

 VSCROLL() 

          The premier scrolling function...bar none.  Many times we've all
          needed a scrolling function like VSCROLL.  The VSCROLL function
          performs video scrolling, either vertically (up and down) or
          horizontally (left and right), and allows the programmer to control
          the attribute of the blank line (or column) left behind by the
          scrolling action.


      Format: 

               vscroll(top, left, bottom, right, lines, dir [,attr])


      Parameters: 

               top.......Numeric variable or constant indicating the top row
                         of the area to be scrolled.  Value checked to be
                         between 0 and 24 inclusive.

               left......Numeric variable or constant indicating the left
                         column of the area to be scrolled.  Value checked to
                         be between 0 and 79 inclusive.

               bottom....Numeric variable or constant indicating the ending
                         row of the area to be scrolled.  Value checked to be
                         greater than TOP but less than or equal to 24.

               right.....Numeric variable or constant indicating the right
                         column of the area to be scrolled.  Value checked to
                         be greater than LEFT but less than or equal to 79.

               lines.....Numeric variable or constant indicating the number
                         of lines or columns to be scrolled, or zero (0) to
                         scroll entire window (effectively erasing it).
                         Value checked to be equal to or less than BOTTOM -
                         TOP if a vertical scroll or equal to or less than
                         RIGHT - LEFT if horizontal.  If greater than the
                         number of available lines or columns within the
                         specified area zero (0) will be assumed.

               dir.......Character string variable or constant, non case
                         sensitive, indicating the direction of the scroll
                         ('u' = Up, 'd' = Down, 'l' = Left, 'r' = Right).

               attr... OPTIONAL .  Character string variable or constant,
                         non case sensitive, containing a valid color command
                         or combination for character and background.  Must
                         be the alpha representation of the color, the
                         numeric will be rejected.  The default is the color
                         attribute currently on the screen for the character
                         in the TOP, LEFT position.

                                  (valid colors)
                          black                          N
                          blue                           B
                          green                          G
                          cyan                           BG
                          red                            R
                          magenta                        RB
                          brown                          GR
                          white                          W
                          intense                        +
                          blink                          *


      Examples: 

               1.   This will scroll one line down in the area from row #10,
                    column #20 through row #12, column #60 using an attribute
                    of black character (n) and white background (w).

                    .
                    .
                    .
                    vscroll(10,20,12,60,1,'d','n/w')
                    .
                    .
                    .

               2.   This will scroll one column to the right in the area from
                    row #05,column #00 through row #20, column #79 using
                    whatever the attribute of the character at 10,20
                    currently is.

                    .
                    .
                    .
                    vscroll(05,00,20,79,1,'r')
                    .
                    .
                    .

      Returns: 

               Nothing.


      Cautions: 

               None.