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                              R A M   P O N G

                               (C) 2009/2017

                              Thomas  Jentzsch


DEVELOPMENT
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Someone at AtariAge was wondering if it would be possible to run anything on
an Atari 2600 without keeping the cart plugged in. Which means within 128 bytes!
I took the challenge and developed RAM Pong, then 2K in size. Most of the space
was used for a fancy option menu and title screen which I have stripped down
this week to fit into 1K.

The fancy and quite well commented 128 bytes kernel manages to:
- read and display two paddles
- display a dotted net and adjust position according to scoring (no space for
  fancy digits within just 128 bytes :)
- move the ball, check its border and paddle collisions and adjust its speed
  and direction accordingly
- play Pong sounds whenever the ball hits something
- detect game over
- create a valid TV signal (which the Atari can't do on its own)

Note:
  Since the code is run in RAM, all variables are right inside the code. So
  (almost) every variables change causes the code to self-modify.
  Two variables have been excluded because they are most space efficiently
  accessed by using PLA and PHA with the stack pointer adjust accordingly.

For that 128 bytes RAM code is heavily optimized. The menu code not so much.

Use DASM to assemble.


THE GAME
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Good old Pong, that's all.


PLAYING THE GAME
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You know the rules, don't you?

The net is there to indicate who is winning. Whenever you miss a ball, it moves
toward your direction. When it reaches your border, game over!


SWITCHES (Stella emulator keys; download: http://stella.sourceforge.net/)
--------
FIRE (LEFT CTRL)           start game
COLOR MODE (F3/F4)         Color = green background; B/W = black background
LEFT DIFFICULTY  (F5/F6)   B = large paddles; A = small paddles
RIGHT DIFFICULTY (F7/F8)   B = slow ball; A = fast ball
ON/OFF (CTRL+R)			       reload ROM for restarting (no other option, sorry)

For Stella you should go into the options menu via TAB key and then at
"Game Properties"/"Controller" set "P0+P1 Controller" both to "Paddles". Also
in "Input Settings"/"Device and Ports" you may want to enable "Grab mouse in
emulation mode". Reload the ROM afterwards to make the changes effective.


DISPLAY
-------
The menu displays the switches status below that nice rotating title. These
are patched into the 128 bytes RAM code when you start the game.

In the game, well...:
Two paddles moving up and down, a ball moving all around and a net moving
left and right.


LEGAL STUFF
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RAM Pong (C) 2009/2017 Thomas Jentzsch
This game is freeware, but copyrighted; it may be freely distributed, but it
must be always accompanied by this documentation file. This program may be
included on websites and shareware or freeware compilations, but please contact
me first. You can't distribute RAM Pong on Atari 2600 cartridges without my
explicit permission. Thomas Jentzsch makes no guarantees, written or implied,
on this software. I'm not responsible for any damage due to the use of this
software.


MISC
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Please send any comments, questions, or suggestions to:

                     tjentzsch@yahoo.de

Enjoy!