Snowflake (Commodore C64/6502 Assembler)

Author: Geir Straume
Category: Christmas Challenge
System: C64
Language: Assembler (64tass)
Len source code: 2005 bytes (source with comments)
Len exe file:    67 bytes
Len code only:   65 bytes (excl. load address)
Instructions:
Start the VICE C64 emulator and drag and drop "snowflake.prg" into the emulator window. Enter SYS 843 to start.

Description:
The program contains nine bytes of bit patterns which are used to display the rows of the snowflake on screen.
A tenth bit pattern is represented by a memory location known to be zero.

Each byte is rotated left for the left part of a row, and then right for the right part. Self-modifying code is
used to change the rotate instruction.

The bit patterns are first used to display the upper rows, and then the lower rows.

See commented source code for further implementation details.