Star64

Author: F#READY / Atari Invasion
Category: Christmas Challenge
System: Atari XL/XE
Language: 6502 Assembly / MADS Assembler

Len source code: 233 bytes
Len exe file: 64 bytes
Len code only: 58 bytes

Instructions:
Use Altirra emulator with Rev.2 OS ROM (default Atari XL/XE OS).
In the emulator:
- System > Firmware > Firmware images... 
- install REV02.ROM under 'Atari XL/XE OS ver.2'.
- File > Boot image
- Choose: star64.xex

Description:
One half of the 17x17 matrix is encoded in bits (0=space, 1=star).
During decoding/printing, the data is placed on the stack.
The second half of the matrix is then printed by pulling the data from the stack.

Comments:
I also made a version with a different approach, but this one is smaller :)