Star for Atari Turbo-Basic XL

Author: dmsc
Category: Christmas Challenge
System:   Atari 8-bit
Language: BASIC
Len source code: 75
Len exe file:    75
Len code only:   75
Instructions:
  With the provided ATR disk image, load Turbo-Basic XL by typing TB15, then
  inside BASIC load the program with ENTER "D:STAR.LST", and type RUN.
Description:
  This program uses the function:

   U = ABS(Y) / 9
   V = ABS(X) / 9
   S = NOT ( (U > 0.5) AND (V > 0.5) OR (ABS(U-V) < 0.5) )

  This is calculated for each point in the X and Y ranges from -8 to 8, drawing
  a star character or a space.

Comments:
 To minimize size, this program uses the fact that Turbo BASIC converts a
 number to integer when doing bitwise operations, so it does away with the
 comparisons.

 Turbo-Basic XL was a very famous extended BASIC for the Atari XL and XE
 computers, it is backward compatible with the original Atari BASIC but adds
 many new statements and operations, and it is much faster.