for the Supercharger

                                by Bob Colbert

What is it?

    The Cheetah allows you to cheat at your favorite games for the Atari
2600 VCS.  With the aid of Cheetah Codes, you can have unlimited lives,
unlimited time, even invincability to get you to those "impossible" levels.

How do you use it?

    The Cheetah is actually two programs in one.  You use The Cheetah
on your PC (Amiga or MSDOS) to convert a ROM image .bin file to either
a .wav file for use with the Supercharger, or a 8448 byte .bin file for
use with the PC Atari Emulator 1.4 or above.

If you want to use Cheetah with a Supercharger, you want to create a .wav.
Once the .wav file is created, you play that into your Supercharger through
your soundcard. (You can also record the .wav file on a tape and play that
into your supercharger if your computer and Atari are far apart).  Instead
of the game starting, you are presented with a code-entry screen, where you
can enter a six-digit Cheetah Code.  When Cheetah starts, you see 6 zeros
on the screen, the word "START" and the Cheetah logo.  If you do not wish
to enter a code, simply press the fire button and the game will start.  If
you do wish to enter a code, use the joystick to move right or left and a
cursor will appear under one of the digits on the screen.  Pushing up on
the joystick will increase a digit's value, which has the range from 0-9 and
A-F.  Pushing down on the joystick will decrease a digit's value. Once you
have the correct Cheetah code entered on the screen, you enter the code by
pressing the joystick button.  When you let go of the fire button, the code
should be all zeros again.  You can enter multiple Cheetah codes before
starting a game, each time by pressing the fire button.  When you are ready
to play the game, simply keep moving the cursor to the left or right until
the word "START" appears in the center of the screen.  At that point,
pressing the button will start the game!  One reminder, if you neglect to
press the fire button while the cursor is under a code digit and then
start the game, the code will not take effect!

If you want to use Cheetah with the PC Atari Emulator 1.4 or above, you
must use the -e (for emulator) flag.  This creates an 8448 byte .bin file
that the emulator will recognize as a Supercharger image.

Where do you get the codes?

    From me, or anybody else who takes the time to make a code up.  The
format of the code is simple enough and is explained in detail later.

Does it work with all games?

    The Cheetah is limited by the hardware of the Supercharger, so it will
only work with 2k and 4k games.  Some games do not work correctly because
they confuse the Supercharger.  I have developed a hardware modificatioin
that allows you to use any 2k or 4k image on the Supercharger.  Please note
that some 2k ROM images still need to be "doubled up" because the coders
were careless in addressing the ROM.  (The address lines for the upper and
lower 2k banks were connected so $f000 = $f800).  I'll probably take care of
this in a later release.

Where do I get The Cheetah?

    At my homepage of course :)


Who helped you?

    Dan Boris - creator of the Virtual VCS for MSDOS.  When I needed that
                vital bit of code to do 6 character graphics, he was there!
                (Thanks Ouphe!)

    Craig Nelson - creator of the Supercharger.  He was nice enough to fax
                   me information on the control byte of the Supercharger.
                   It, along with a lot of experimenting, proved priceless.

What's Next?

    Well, I am going to try and make a good sized library of Cheetah Codes.
Then I want to make a game for the Supercharger.

O.K. now for the technical stuff:

Cheetah command format:

    Cheetah [-f][-e] romfile wavefile (binfile if -e is used)

        The f makes a "super-fast load" version of the .wav file.

Cheetah code format:

                            7 7 B E A A
                            \   / |_| |_ Number of addresses (minus 1)
                             \ /   |      to modify
                              |    |                           
              Address to _____/     \___ Byte to put at address

 The last digit is the number of addresses to modify (minus 1).  The code
 above is a code for Chase the Chuckwagon, it give unlimited time.  It
 modifies the game at address $F77B, and puts 11 ($0a + 1) EAs (NOPs) there.

                        Have Fun!

                                Bob Colbert