SNOW

Author: regregex
Category: Christmas Challenge
System: Acorn Archimedes, Acorn RISC PC
Language: Assembler (BBC BASIC V)
Len source code: 407 bytes
Len exe file:    116 bytes
Len code only:   116 bytes
Instructions:
  Install and open RPCEmu
  ( https://www.marutan.net/rpcemu/easystart.html ).
  Click on the Apps directory on the taskbar, then double-click
  on !SparkPlug.  Its icon will appear on the taskbar.
  In the host OS (e.g. Windows), copy this zipfile into the hostfs
  directory of the installed copy of RPCEmu.
  Click the HostFS: icon on the taskbar and navigate to the zipfile.
  Drag it onto the !SparkPlug icon on the taskbar; a viewer window
  will open.
  Double-click on snow to run the binary.

Description: The program displays a specific snowflake pattern on the
screen.
It selects display MODE 4, which automatically clears the screen.  For
each character cell in a large rectangle in the top left corner it
prints an asterisk, if marked on one of two copies of a bitmap, or if
lying on an axis; otherwise a space is printed.  The program waits for a
keypress before exiting.

Comments:
Annotated source code can be found in notes.txt.

This program and its assembler also run on a SPROW ARM7TDMI Coprocessor
attached to a BBC Micro.  Line 20 must be modified to suit the host's
filing system:
...:SYS8,0,"snow",&8000,&8000,s,x:...