Zapactris for the unexpanded VIC-20
-----------------------------------
(c) 2002 Anders Carlsson [Zapac] <anders.carlsson@mds.mdh.se>

This game is part of the Minigame Compo (http://www.ffd2.com/minigame/). It
is written in machine code, and the source will be available as soon as the 
competition deadline has passed (september 2002).

Zapactris is an yati (i.e. Yet Another Tetris Implementation) which runs on
the VIC-20. So far, the author hasn't seen a single Tetris clone on the VIC
which is part of the reason this one was written. This project was started
in Januari 2000 but was rewritten from scratch in August 2002.

Controls
--------
Use a joystick! Finally I got an clue how to write such routines without
using too much memory. Fire button rotates piece, pull down to drop it. Be
careful not to keep the stick down too long, as a subsequent piece then may
be unvoluntarily.

Scoring
-------
Only full lines are counted (and removed with some awful graphic effects,
but then I'm the *musician* in VVV/VIMM, not graphic artist or coder). You
get no particular bonus for removing multiple lines, other than the pause
it takes to clean them off screen. The game will in four stages play faster 
and faster, but the fastest speed should still be reasonably playable.

Memory usage
------------
The executable is 1004 bytes plus loading address. It uses a fair amount of
the zeropage, and you may better detach any RS-232 equipment from your VIC
as some of the used space is RS-232 pointers.

To distinguish between the previous pieces and the current one, the latter
actually is background white but with multicolour attribute set. Not until
it reaches its destination the colour is actually stored in memory.

Bugs
----
When using Basic/Kernal routines for RND, multiplication etc there was a
spurious "?OVERFLOW ERROR" from time to time, which is why the game only
reads the system clock to generate crude pseudo random. This error should
not happen on the released version.

Notice that the 'next' piece displayed when the game is ended will be your
first piece on the next game you play.


