Atari7800_MapperGuide.txt

ATARI 7800 BANKSWITCHING GUIDE
(c) copyright by Eckhard Stolberg ([email protected])
last modified on February 25, 2003 (version 1.00)

Thanks to:
Lee Krueger, Graham Percy, Dan Boris, Chad Schell and Mitch Orman
==============================================================================
7800 games can use the memory from $0400 to $047f, from $0500
to $17ff and from $2800 to $ffff, but only the High-Score cart
uses anything below $4000. It has 4KB of ROM at $3000-$3fff
and 2KB of battery-backed RAM at $1000-$17ff.


The non bankswitching games (7808, 7816, 7832 and 7848) just
use the specified amount of ROM from $ffff downwards.


Then there are several different types of Atari's SuperGame
bankswitching. It basically consists of 8 16KB banks (0-7)
that can be mapped in at $8000-$bfff. Bank 7 always is fixed
at $c000-$ffff. To map in a chosen bank into $8000-$bfff you
write it's bank number (0-7) to any address between $8000-bfff.
The contend of $4000-$7fff differs between different variations
of this type:

Some games have nothing connected in this area and return only
random data.

Some games have bank 6 fixed at this area.

Some games have 16K of extra ROM there. Those games are 144K
in size and are marked as 78S9 in the list.

Some games have either 8K of RAM at $6000-$7fff or 16K of
RAM at $4000-$7fff.

Some games have a POKEY chip mapped in at this area. It
has 16 addresses that get repeated all the way between $4000
and $7fff.

Some games only have 4 ROM banks at $8000-$bfff (0-3). Banks
4-7 either return the same data as banks 0-3 or completely
random data. PAL Karateka is a special case. It only uses
banks 4-7. Banks 0-3 are random data and bank 6 is also fixed
at $4000-$7fff.


F18 Hornet has it's own bankswitching format (78AB). It has
32K of fixed data at $8000-$ffff and 2 16K banks at $4000 -
$7fff. The two banks get mapped in by writing either $01 or
$02 to address $8000. I don't know if other addresses trigger
the bankswitching too, but I'm assuming any address above
$8000 might work. I have no idea what happens when you write
other values to the hotspot, but they probably will just be
ignored.


Double Dragon and Rampage have a very wierd bankswitching
scheme (78AC). It has 8 16K banks (0-7) that get mapped in at
$a000-$dfff. Write accesses to addresses above $ff80 trigger
the bankswitching. This sets the bank according to the low
nibble of the address. So a write to $ff80 maps in bank 0,
a write to $ff81 maps in bank 1, etc. The games only use
addresses $ff80-$ff87, so I'm not sure if other addresses
trigger the bankswitching too.

If we are assuming that a bank reaches from $a000-$dfff,
then the rest of the ROM space looks like this:

$4000-$5fff second 8kb of bank 6
$6000-$7fff first 8kb of bank 6
$8000-$9fff second 8kb of bank 7
$e000-$ffff first 8kb of bank 7



Type  RAM  POKEY  TV     Name

78SG    0   no    NTSC   Ace of Aces
78S9    0   no    NTSC   Alien Brigade
7816    0   no    NTSC   Asteroids
7832    0   yes   NTSC   Ballblazer
78SG    0   no    NTSC   Barnyard Blaster
78SG    0   no    NTSC   Basketbrawl
7816    0   no    NTSC   Centipede
7832    0   no    NTSC   Choplifter!
78SG    0   yes   NTSC   Commando
7808    0   no    NTSC   Colour Test
78SG    0   no    NTSC   Crack'ed
78S9    0   no    NTSC   Crossbow
78SG    0   no    NTSC   Dark Chambers
7848    0   no    NTSC   Desert Falcon
7816SG 144  no    NTSC   Development Cartridge (Atari)
7832    0   no    NTSC   Diagnostic Cartridge
7816    0   no    NTSC   Dig Dug
7848    0   no    NTSC   Donkey Kong
7848    0   no    NTSC   Donkey Kong Junior
78AC    0   no    NTSC   Double Dragon
78AB    0   no    NTSC   F18 Hornet
78SG    0   no    NTSC   Fatal Run
78SG    0   no    NTSC   Fight Night
7832    0   no    NTSC   Food Fight
7832    0   no    NTSC   Galaga
7848    0   no    NTSC   Hatrick
78HS    2   no    NTSC   High-Score Cartridge (RAM is battery backed)
78SG    0   no    NTSC   Ikari Warriors
78SG    8   no    NTSC   Impossible Mission
78SG    8   no    NTSC   Jinks
7832    0   no    NTSC   Joust
7848    0   no    NTSC   Karateka
78SG    0   no    NTSC   KLAX (prototype)
7832    0   no    NTSC   Kung-Fu Master
7848    0   no    NTSC   Mario Bros.
78SG    0   no    NTSC   Mat Mania Challenge
78SG    0   no    NTSC   Mean 18 Ultimate Golf
78SG    0   no    NTSC   Meltdown
78SG    0   no    NTSC   Midnight Mutants
7816*2  8   no    NTSC   Monitor Cartridge (Harry Dodgson)
                         (16KB for 7800 mode and 16KB for 2600 mode
                          RAM is battery backed)
78SG    0   no    NTSC   Motor Psycho
7816    0   no    NTSC   Ms. Pac-Man
78SG    0   no    NTSC   Ninja Golf
7848    0   no    NTSC   One on One Basketball
7832    0   no    NTSC   Pete Rose Baseball
78S4    0   no    NTSC   Pitfighter (prototype)
78SG    0   no    NTSC   Planet Smashers
7832    0   no    NTSC   Pole Position II
78AC    0   no    NTSC   Rampage
78S4    0   no    NTSC   Realsports Baseball
7832    0   no    NTSC   Robotron
78SG    0   no    NTSC   Scrapyard Dog
78SG    0   no    NTSC   Sentinel (prototype)
78SG   16   no    NTSC   Summer Games
7848    0   no    NTSC   Super Huey UH-IX
7832    0   no    NTSC   Super Skateboardin'
78S4    0   no    NTSC   Tank Command
7832    0   no    NTSC   Titlematch Pro Wrestling
7832    0   no    NTSC   Tomcat F14
78SG    0   no    NTSC   Touchdown Football
78S4    8   no    NTSC   Tower Toppler
78S4    0   no    NTSC   Waterski
78SG   16   no    NTSC   Winter Games
78SG    0   no    NTSC   Xenophobe
7832    0   no    NTSC   Xevious

missing:
GATO prototype
Plutos prototype
Sirius prototype
Chuck Norris: Missing in Action prototype


78SG    0   no    PAL    Ace of Aces
78S9    0   no    PAL    Alien Brigade
7816*   0   no  PAL/NTSC Asteroids (BIOS)
7832    0   yes   PAL    Ballblazer
78SG    0   no    PAL    Barnyard Blaster
78SG    0   no    PAL    Basketbrawl
7816    0   no    PAL    Centipede
7848    0   no    PAL    Choplifter!
78SG    0   yes   PAL    Commando
78SG    0   no    PAL    Crack'ed
78S9    0   no    PAL    Crossbow
78SG    0   no    PAL    Dark Chambers
7848    0   no    PAL    Desert Falcon
7832    0   no    PAL    Dig Dug
7848    0   no    PAL    Donkey Kong
7848    0   no    PAL    Donkey Kong Junior
78AC    0   no    PAL    Double Dragon
78AB    0   no    PAL    F18 Hornet
78SG    0   no    PAL    Fatal Run
78SG    0   no    PAL    Fight Night
7848    0   no    PAL    Food Fight
7848    0   no    PAL    Galaga
7848    0   no    PAL    Hat Trick
78SG    0   no    PAL    Ikari Warriors
78SG    8   no    PAL    Impossible Mission
78SG    8   no    PAL    Jinks
7848    0   no    PAL    Joust
78S4    0   no    PAL    Karateka (uses banks 4-7 instead of 0-3)
7832    0   no    PAL    Kung-Fu Master
7848    0   no    PAL    Mario Bros.
78SG    0   no    PAL    Mat Mania Challenge
78SG    0   no    PAL    Mean 18 Ultimate Golf
78SG    0   no    PAL    Meltdown
78SG    0   no    PAL    Midnight Mutants
78SG    0   no    PAL    Motor Psycho
7832    0   no    PAL    Ms. Pac-Man
78SG    0   no    PAL    Ninja Golf
7848    0   no    PAL    One on One Basketball
7832    0   no    PAL    (Pete Rose) Baseball
78SG    0   no    PAL    Planet Smashers
7832    0   no    PAL    Pole Position II
78SG    0   no    PAL    Scrapyard Dog
78SG    0   no    PAL    Sentinel
7848    0   no    PAL    Super Huey UH-IX
7832    0   no    PAL    Super Skateboardin'
7832    0   no    PAL    Titlematch Pro Wrestling
7832    0   no    PAL    Tomcat F14
78S4    8   no    PAL    Tower Toppler
78SG    0   no    PAL    Xenophobe
7848    0   no    PAL    Xevious

no PAL version released (?):
Rampage
Realsports Baseball
Robotron
Summer Games
Tank Command
Touchdown Football
Water Ski
Winter Games