Invaders09 updated to 1.04

Invaders09 1.04 title screen.
Invaders09 1.04 title screen.

Sub-Etha Software has released another update to our Color Computer 3 OS-9 space invaders-style game, Invaders09. Version 1.04 is now available and is a recommended upgrade for all users. It supplants previous February 1995 release of 1.03. As with all Sub-Etha Software products, bug fixes and maintenance releases are free upgrades.

You may download the 1.04 update as a self-booting .DSK image from our update server:

The INVADE09.DSK image includes a fully bootable version of NitrOS-9 v3.3.0 and may be ran directly on a real Color Computer 3 or emulator just by mounting the image and typing “DOS”. You may also copy the invaders1.04.txt documentation file and CMDS/invaders1.04 binary to your existing OS-9 Level 2 or NitrOS-9 6309 or 6809 system.


  • Updated title screen (website, new message).
  • Added “secret” options to help screen.
  • Fixed bug that made font not always load.
  • Fixed shield and border graphics, palette cleanup.


  • After 20 years, the game still doesn’t have an “attract mode” or “high score” listing. Maybe 1.05 will be out by 2025 to fix this. (Sorry about that, Bob Devries!)
  • The documentation refers to the binary as being called “invaders” but it is really “invaders1.04” on this release. Maybe the author won’t be so lazy next time and will name the binary correctly.


File:  INVADERS.TXT - Revision 1.2 (2/7/2015) - By Allen C. Huffman

|   I    NNNNN  VV  V   AAA   DDDD   EEEEE  RRRR   SSSSS   |
|   I    N   N  VV  V   A A   D   D  E      R  R   S       |
|   II   NN  N   V V   AA  A  DD  D  EE     RR  R     SS   |
|   II   NN  N    V    AA  A  DDDD   EEEEE  RR  R  SSSSS   |
The Invasion Begins!

By Allen C. Huffman
Copyright (C) 1994,1995,2015 by Sub-Etha Software


     For years, determined scientists have probed the endless boundries of the
universe for extra-terrestrial signals.  Countless satellites have been
launched, radio signals transmitted, and theories formulated...all without
results.  Until now...
     Far out in the eastern spiral arm of the galaxy, something was listening.
And this something didn't like what it heard.  Soon outposts around the planet
were picking up masses moving towards the Earth.  The planet was preparing for
first contact, but no signals came from the void.
     The scientists prepared their welcome speeches.  The government, of
course, prepared defense actions.  The tabloids prepared headlines about the
end of the world.  The invasion began.
     Without warning, waves of disc shaped ships filled the skies.  Blasts of
energy were fired on unsuspecting buildings, knocking out military
installations before any retaliation strikes could be launched.  The Earth was
defenseless except...of course...for one last hope.
     The E.T.H.A. (Extra Terrestrial Hope Association) had planned for the
worst when the big day of contact would arrive.  Along with an endless supply
of peaceful translation equipment they possessed an experimental plasma cannon.
 This would be Earth's only chance for survival.
     You, my friend, are the control operator of this cannon.  Good luck.


     Invaders09 is a self contained executable called "Invaders".  Copy it to
your CMDS directory.  Usage is as follows:

     Invaders 1.04 by Allen Huffman (
     Copyright (C) 1994,95,2015 by Sub-Etha Software.

     Syntax: Invaders [-opts]
     Usage : LEFT/RIGHT to Move, SPACE to Fire, P to Pause, Q to Quit.
     Opts  : -? = display this message.
             -m = monochrome colors (for 'montype m' displays).
             -z = secret option if you think it is too slow.
             -* = secret cheat mode (press * to skip level).


     At the title screen, joystick users should press "J" or the fire button to
start the game.  [Note:  The joystick must be plugged into the left joystick
port.]  For keyboard control, press "K".  "Q" will quit back to OS-9.
     The game will begin and the playfield will appear.  The object is simply
to move your cannon (at the bottom of the screen) left and right to shoot at
the bad guys.  Direct hits are required as any side shots will be absorbed
harmlessly by the invaders.  Also, equipment limitations prevent your plasma
cannon from moving and firing at the same time.  Readouts at the bottom of the
screen display your current score, round, power rating, and lives remaining.

     Scoring:  Each invader you hit earns you 10 points.  Occassionally, a
mother ship ufo will pass across the top of the playfied.  Destroying it is
worth 100 points.
     Rounds:  After clearing out all fifty invaders, a new round will begin. 
The invaders will start closer to the ground.
     Power:  This determines how many shots your cannon can fire at a time. 
Each round gives you an extra shot up to the maximum of "J" (10 shots).  Each
time you lose a life your power goes down by one to the minimum of "B" (two
     Lives:  You start with three cannons.  Use them wisely.  Without them the
dreaded "Game Over" message will appear.
     Pause:  During game play, press "P" to pause the game.
     Quit:  Pressing "Q" during a game will quit.

     You have three shields to hide under.  Be warned:  They do not protect you
from bombs dropped by the mothership.  Also, when the invaders get low enough
your shields will disappear.  Be warned again.


     As with all classic arcade games, the enemies are never ending.  Each
level causes the enemies to start closer and closer to the ground and they get
faster and faster.  Good luck!


     Special thanks to YOU for helping support the future of the CoCo and OS-9
by supporting vendors such as ourselves.  Without you, our hobby would have
died years ago.


     Thanks to Bob Devries, Robert Gault, Colin McKay, Alan DeKok and the late
Alex Forrest for helping beta test this product and get it to this stage.


Programming on Invaders09 began on 8/21/94 and it debuted at the 1994 Atlanta

* 1.00 09/24/94 - Release version for 1994 Atlanta CoCoFest!
* 1.01 10/26/94 - Robert Gault patch for >512K systems
*                 Since NitrOS9 call does not work for >512K, call removed
* 1.02 01/29/95 - Converting to 16-color gfx screen (whew!)
* 1.03 02/04/95 - Added test for valid screen BEFORE mapping it into MEM R.G.
*                 Moved hiscore and packet (=enemies) to dp. A.H.
* 1.04 02/07/15 - Updated title screen (website, new message).
*                 Added "secret" options to help screen.
*                 Fixed bug that made font not always load.
*                 Fixed shield and border graphics, palette cleanup.



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