The Turbo-Freezer, made by the German Bernhard Engl, is a small circuit board that plugs into the PBI slot of your Atari XL (There was also a XE version of the freezer). It allows you to stop every program by pressing the red button on the Freezer. You could then save the current execution state to (ram)disk and reload it at a later time to continue playing. It has also has a monitor/disassembler which allowed you to change the current memory contents and then continue the program's execution. By changing the right memory locations, you could alter games so that you have for example unlimited lives.

Turbo-Freezer XL made by Bernhard Engl
One this page you will find many Freezer codes I've discovered. Also in the list are cheat codes already hidden in the game.
How it works
The Freezer codes must be entered in the debugger of the Turbo-Freezer. The
game must be stopped, the codes be entered and then the game can be resumed.
Some code must be entered before you play while others must be entered while you
are playing.
The codes published here are in the Turbo-Freezer format. For example:
CC234<FF,EA,03
C25<34
Means: Change the contents of address $C234 to $FF, address $C235 to $EA,
address $C236 to $03 and address $25 to $34.
With this information you can use these codes also if you have another kind
of freezer or emulator with debugger capabilities. For example, the same in the
monitor window of the Atari800Win PLus 3.1 emulator is:
C C234 FF EA 03
C C25 34
The code to disable collision detection ($D01D) won't work in Atari800Win. Use the disable collision detection of the emulator instead.
If you have other cheats or Freezer code, please e-mail them to me and I will
add them to the list.
Action Biker
| C8AD7<30 | 255 lives | Before playing |
Airstrike II
| CD01D<00 | Invisible | While playing |
| C664<FF,FF | 255 lives both players | While playing |
Airwolf
| CD01D<00 | Invisible | While playing |
Amaurote
| C6275<EA,EA | No damage | |
| C61E7<EA,EA,EA CC206<EA,EA,EA | Don't die if the city is destroyed | |
| C60F8<EA,EA,EA | Don't die if no money |
Arena
| C7B<FF | 255 lives | While playing |
Bounty Bob Strikes Back!
To die while playing type: 8187826861
Set the code in the option menu on 61,800. Then press 'F' plus <OPTION>
Now you can press the following keys while playing:
Bruce Lee
| C26<80 | 128 lives | While playing |
Bubble Trouble
| C2DDF<FF | 255 lives | Before playing |
| C68F<FF | 255 lives | While playing |
Caverns of Khafka
| C2567<09 | 255 lives | While playing |
Caverns of Eriban
| CD01D<00 | Invisible | While playing |
Cross
| CD01D<00 | Invisible | While playing |
Desmond's Dungeon
| C1042<FF | 255 lives | While playing |
| C1040<FF | 255 power | Whil playing |
Domain of the Undead
| CD01D<00 | Invisible | While playing |
Druid
To destroy skull, stand against it and fire CHAOS.
| C577A<FF,FF,FF,FF,FF,FF,FF | 255 of everything | While playing |
Elektraglide
| C2EF0<EA,EA,EA | No slow down if you hit the sides | |
| C2EB1<EA,EA,EA | No slow down if you hit the tunnel sides |
Flak
| CD01D<00 | Invisible | While playing |
| CD01D<EE | Enemy doesn't fire | While playing |
Flip & Flop
| C87<FF | 255 lives | While playing |
| C8E<FF,FF | A lot of time | While playing |
Ford Apocalypse
| CD01D<00 | Invisible | While playing |
| CFC<99 | 99 lives | While playing |
Green Beret
| C5096<EA,EA C509B<EA,EA C516A<EA,EA,EA |
Do not die anymore |
Henry's House
Type in title screen "CPM" for unlimited lives.
H.E.R.O.
| C9C01<60 | No enemies |
International Karate
Type 'X' and then 1-4 to select speed.
Jet Boot Jack
| C5D3B<A4 | 255 lives | Before playing |
| C2464<A4 | 255 lives | While playing |
Jet Set Willy
| C38DF<80 | 255 lives | Before playing |
| C46F3<80 | 255 lives | While playing |
Joust
| CA8<80,80 | 128 lives |
Laser Hawk
Type 'B' in title screen then you can't die anymore.
| C672<F0 | 255 lives player 1 | While playing |
| C677<10 | 255 lives player 2 | While playing |
| CD01D<00 | Invisible | While playing |
Last V8
| C134F<EA,EA,EA | Can ride through all obstacles |
L.A. Swat
| C66A<3 | Set number of lives back to 3 | While playing |
Loco
| C5AFF<FF | 255 lives | Before playing |
Mario Bros.
| C29<FF | 255 lives | While playing |
MegaBlast I
Type in title screen "HAVE FUN" for options menu.
Mega Mania
| CDC<7F,7F | 128 lives for both players | While playing |
Miner 2049er
Type while playing "213782686" and then <SHIFT> + level number to warp to chosen level.
| CB9<A | 10 lives | While playing |
Molecule Man
| C605<FF,FF,FF | 255 pills, bombs and money | While playing |
Montezuma's Revenge
| C88<FF | 255 lives | While playing |
Mouse Trap
| C50<FF | 255 lives | While playing |
Mr. Robot
| CC4<FF | 255 lives | While playing |
Mrs. Pacman
| C93<80,80 | 128 lives | While playing |
Nibbler
| CDE<FF | 255 lives | While playing |
| CDF<FF,FF | A lot of time | While playing |
Oil's Well
| CD01D<00 | Invisible | While playing |
Ollies Follies
Level codes. Type them while playing.
| C2E04<FF | 255 lives player 1 | Before playing |
| C2E09<FF | 255 lives player 1 | Before playing |
| C3680<FF,FF | 255 lives both players | While playing |
Pacman
| CD01D<1 | No ghosts | While playing |
Panic Express
Freezer codes: C9FA4<FF,FF,FF While playing. A lot of time.
C628<FF While playing. 255 lives.
| C9FA4<FF,FF,FF | A lot of time | While playing |
| C628<FF | 255 lives | While playing |
Pitfall
| CCE<FF | 255 lives | While playing |
Pogo Man
| CD01D<00 | Invisible | While playing |
Preppie II
| CD01D<00 | Invisible | While playing |
River Raid
| C6A<CF | 207 lives | While playing |
Sea Dragon
| CD01D<00 | Invisible | While playing |
Snokie
| C87<FF | 255 lives | Before playing |
| C9F<FF | 255 lives | While playing |
Space Hawk
| C67B7<99 | 99 shields | Before playing |
| C678D<level no. | Start with level no. 1-6 | Before playing |
| C6727<99 | 99 shields | While playing |
| C6728<level no. | 99 shields | While playing |
| CD01D<00 | Go to level no. 1-6 after finishing current | While playing |
Spindizzy
| CBD<03 | While playing. A lot of time | While playing |
| C742E<D0 | Unlimited time |
Starquake
Teleporter codes:
Bring objects to WHOLE and then go up, right, right.
| C1DC3<FF | Start with 100 lives | Before playing |
| CD2<FF | Maximum number of lives | While playing |
| CD3<74 | Maximum number of power | While playing |
| CD4<74 | Maximum number of steps | While playing |
| CD5<FF | Maximum number of shots | Whil playing |
Stealth
| CABCC<FF | 255 lives | While playing |
Steeple Jack
| CD01D<00 | Invisible | While playing |
Sticky Bear Basket Bounce
| CC84<EA,EA,EA | Unlimited lives |
Super Zaxxon
| C5AFD<FF | 255 lives | Before playing |
Tank Commander
| CC7<FF | 255 lives | While playing |
The Extirpator
| C50BD<EA,EA,EA | Unlimited lives |
The Goonies
| C112C<80 | 128 lives | While playing |
The Living Daylights
Pick the objects in the following order:
| C80AF<99 | More power | While playing at the start of each level |
The Tail of Beta Lyrae
| C4A<FF | 255 lives | While playing |
| CD01D<00 or DD | Invisible | While playing |
Trailblazer
| C2721<11 C2723<16 |
Set time to x1:6x:xx | While playing |
Whirlinurd!
Code word is: "IAMTHEHUNGRYDUDE"
Who Dares Wins II
| CE366<39,39 | 99 lives | While playing |
Zaxxon
| C8C<FF | 255 lives | While playing |
ZYBEX
| C2844<EA,EA,EA | Unlimited lives player 1 | |
| C2864<EA,EA,EA | Unlimited lives player 2 | |
| C285B<EA,EA,EA | No weapon power decrease player 1 | |
| C287B<EA,EA,EA | No weapon power decrease player 2 | |
| C188C<04 C18BD<04 |
Start with full armory | |
| C280D<EA,4C,84,28 | Invulnerable both players | |
| C2367<EA,EA,EA | Turn off enemy shooting | |
| C3A30<EA,EA,EA,EA C39E5<EA,EA,EA,EA |
Turn off background |