User`s manual

I-2
This statement would allow you to use array elements A(0) through
A(30). Of course, you can use any variable name as an array name in
LEVEL II BASIC.
6. In LEVEL I, an INPUT statement allows you to type in variables and
expressions, not just constants. In LEVEL 11, you have to type in a
constant, either string or numeric, depending on the INPUT variable.
Example:
Y=1: N=0: INPUT "YES OR NO (Y/N)";R
change
IF R=1 THEN PRINT "THAT'S BEING POSITIVE!"
to
INPUT "YES OR NO (Y/N)";R$
IF R$="Y" THEN PRINT "THAT'S BEING POSITIVE!"
7. In LEVEL II, DATA statements must contain constants only no variables
or expressions.
8. In LEVEL I, a True logical expression is evaluated as a 1; in LEVEL II,
the same expression has the value -1. Therefore if your LEVEL I program
uses such expressions, you need to change them accordingly in the
converted program. Example, to compute MAX(A,B):
change
M = (A<B)*B + (B<A)*A
to
M = (A<B)*B - (B<A)*A
9. In LEVEL I, POINT(x,y) returns 1 when graphics block (x,y) is ON, and 0
when it is OFF. But in LEVEL II, POINT (x,y) returns -1 for (x,y) ON,
and 0 for (x,y) OFF. So be sure to allow for this difference. Example:
change
C = C + POINT(X,Y)
to
C = C - POINT(X,Y)
if you want to increment C each time (x,y) is ON.