User`s manual

8-2
Examples:
100 SET(RND(128)-1,RND(48)-1)
Lights up a random point on the Display.
100 INPUT X,Y: SET(X,Y)
RUN to see where the blocks are.
RESET
(x,y)
Turns off a graphics block at the location specified by the coordinates x and y.
This function has the same limits and parameters as SET(x,y).
200 RESET(X,3)
CLS
"Clear-Screen" – turns off all the graphics blocks on the Display and moves
the cursor to the upper left corner. This wipes out alphanumeric characters
as well as graphics blocks. CLS is very useful whenever you want to present
an attractive Display output.
5 CLS
10 SET(RND(128)-1,RND(48)-1)
20 GOTO 10
POINT
(x, y)
Tests whether the specified graphics block is "on" or "off". If the block is "on"
(that is, if it has been SET), then POINT returns a binary True (-1 in LEVEL
II BASIC). If the block is "off", POINT returns a binary False (0 in LEVEL II
BASIC). Typically, the POINT test is put inside an IF-THEN statement.
100 SET(50,28): IF POINT(50,28) THEN PRINT "ON" ELSE PRINT "OFF"
This line will always print the message, "ON", because POINT(50,28) will
return a binary True, so that execution proceeds to the THEN clause. If the
test failed, POINT would return a binary False, causing execution to jump to
the ELSE statement.