Apple IIe - Page 153

Apple BASIC Reference Guide 153
Configuration
SCRN (x,y)
x and
y can range from 0 to 47. If x is in the range from 0 to 39,
SCRN will return the color code of the point whose column is
indicated by x and whose row is indicated by y.
If x is in the range from 40-47 and y is in the range from 0-31,
SCRN
will return the color of the point whose column is equal to
x-40 and whose row is equal to y+16.
If xis in the range from 40-47 and y+16 is in the range from 39-47,
SCRN
will return a number related to the text character in the
text area before the graphics screen. If y+16 is in the range 48-63,
SCRN
will return a meaningless number.
When x is in the range 0-39 and y is in the range 0-23, the
following expression will return the ASCII code of the character
at
that position.
SCRN (a, 2*6) + 16*SCRN (a, 2*b+1)
The character itself
will be returned when the CHR$ function is
executed using the value returned by the above expression as its
argument.
When SCRN is executed in the high resolution graphics mode,
SCRN will continue evaluating the low resolution area of
memory. _The value returned by SCRN will have no relation to
the high resolution screen.
SCRN
is only regarded as a reserved word when the next non-
space character is the left parenthesis.