1. GameBoy: General Description 2. GameBoy-related resources on the Net 3. Cheats, Passwords, Strategies, etc. 4. List of the best games 5. GameGenie Questions 6. Various questions 7. Programming, Hardware, etc. *** Unanswered Questions
People, could somebody subscribing for "Electronic Gaming World" and other similar magazines go through the "S.W.A.T." sections in them and write down all GameBoy cheats/passwords/etc. not included into this file? I would appreciate your help.
Also, there is a lot of GameGenie codes posted recently in r.g.v.nintendo and GB mailing list which are not listed in the official Galoob updates. Could somebody compile these codes into a separate list?
Another thing needed by me and many other people on the Net who requested it is map for GB Metroid. If you have this map in some magazine or a strategy guide, *PLEASE* scan it and send the .GIF [or whatever file you get] to me. If you don't have a scanner, xerox it and send copy to me by snail-mail. My address is
Marat Fayzullin 6304 Hampton Place Elkridge, MD 21227 USA
********************* I. GameBoy: General Description ************************
CPU: 8-bit Z80 work-alike at 4.194304MHz RAM: 8kB internal ROM: 256kBit, 512kBit, 1MBit, 2MBit and 4MBit cartridges are known (32kB, 64kB, 128kB, 256kB and 512kB). Probably, there are 16kB cartridges as well. VRAM: 8kB internal
Sound: 4 channels each of which can be mapped either to the left or to the right or to both speakers
Video: Display: Reflective LCD 160x144 dots Colors: 4 shades of gray Sprites: 40 sprites of either 8x8 or 8x16 [switchable]
Communications: Serial port Up to 4 Gameboys can be connected together using these ports
Power: 6 Volts, 0.7 Watts 4 AA Batteries - 35 hours OR Rechargable battery (NAKI) - 12 hours
* What are the advantages of GB in comparison with other portable videogames?
The same reflective LCD screen which is considered to be the weak point of GameBoy, is its advantage. Other systems, such as Atari Lynx or SEGA GameGear, use backlighted color screens which consume several times more power than reflective LCD of GB. Thus, these systems need 6 AA batteries instead of 4 AAs needed by GB and drain these batteries in about 6 hours. Also, dots on GB's LCD are much smaller than dots on the color screens of other portables which [given that you have a good light source nearby] means that GB's LCD looks crisper. The other advantage of GameBoy is that it is the only portable videogame you can actually PUT INTO YOUR POCKET. Both Lynx and GameGear are too big for it. Speaking about variety of games available for GB, I would *NOT* consider it an advantage of GB if we are talking solely about its technical characteristics. Amount of software written for the system has nothing to do with the system's hardware architecture. It is rather determined by commercial success of the system and, in fact, by how it is marketed. There are many technologically superior systems which just didn't make it because of the poor marketing [TurboGrafx is an example].
************** II. GameBoy-related Resources on the Net *************
7. GameBoy Mail-Server -- M. S. Manley [manley@iies.ecn.purdue.edu] * gameboy@expert.cc.purdue.edu Send mail with word archive in the subject and a list of commands in the body. First, send a single command "help" to get a list of other commands.
8. GameBoy Mailing List -- Andy Norman [ange@hplb.hpl.hp.com] * gameboy@cuckoo.hpl.hp.com To subscribe, unsubscribe or get information send mail to gameboy-request@cuckoo.hpl.hp.com.
****************** III. Cheats, Passwords, Strategies, etc. ******************
[?] - this cheat didn't work for me ------------------------------------------------------------------------------ 1. Castlevania II: Belmont's Revenge passwords
H - Heart C - Candle B - Ball . - Space
Central Castle: HBC. Hard Mode (like Castlevania I): .B.B Belmont's son's realm: HCBB Music Test: HHHH Count Dracula: BHCH Easy Mode (9 lives): CCHH ------------------------------------------------------------------------------ 2. Nemesis cheats
Pause the game and press these buttons:
To get SPEED and SHIELD: BBBBBAAAAA To get SHADOWFIGHTERS,SHIELD,LASER,MISSILES: UUDDLRLRBA
5:HAHA 9:GRIN 13:REAP 17:SEED 21:GROW 25:TALL 29:YALI ------------------------------------------------------------------------------ 5. Last password in Dr.Franken: JHT87 [HEART]V7VN VG20Z ------------------------------------------------------------------------------ 6. How to get to Medusa Cave in Final Fantasy Adventure?
Find an oasis with two palm trees and walk in 8-like manner around them:
Start on level one. Find an exit. Shoot it five times, then explore the level some more. You will find extra lives and speed-up power-ups. You will also have five exits to choose from, each of which takes you to a different level (level select).
Contributed by Mark Kaufman. ------------------------------------------------------------------------------ 8. Zen the Intergalactic Ninja passwords:
C - Can B - Bottle T - Tire A - cArdboard box . - Space
Passwords: [.CBB] [T.AT] [CBAB] ...and the final one: [BTCC] ------------------------------------------------------------------------------ 9. Cheats in Final Fantasy Legend II:
On some stage of the game double-clicking on the Trashcan [or, maybe, trying to "move" Trashcan to the different position in the list] will allow to increase Agility or Strength of the party members. This trick appeared only once and I couldn't repeat it. I also got responses from two people who encountered similar effect. Everybody who has more info on this trick, send email to me.
Here is some mail I got: "I clicked twice on the trashcan, then the list showing my 4 players was shown. I clicked on one of them and his strength and agility was increased. After increasing my other players strength many times with this method, an error, or glith occured, for my pieces of mana went haywire. When I would use the trashcan method, the number of mana pieces would go down. And when I used the compass to locate the pieces, it would give me some bizarre number. If I can remember, I had about 53-57 pieces collected before I began increasing my player's status. Also, I had to start a new game after that because the game wouldn't register that I had any mana, and I couldn't go anywhere in the pillar of sky." -- JSem33@aol.com
Another interesting cheat known as "Dragon Ride": In the race world, with mutants in your party, your can ride the dragon off the track and around the world. Simply fight the boss ones with screen icons on the track (the ones with the magi) until a mutant gets teleport. Save before you fight the monsters; that way, if you don't get teleport, you can just press all four buttons to reset the game and try again. Use this skill while on the dragon. You can then ride around the world quickly, and move through walls. You can go all the way to the end of the game and get cool weapons by going through celestial doors backwards, and then zooming around to a higher level exit. The dragon will occasionally be lost during story sections of the game, but can always be retreived by starting a race again. NEVER CROSS THE FINISH LINE!!!
Contributed by Javan Gargus ------------------------------------------------------------------------------ 10. Tecmo Bowl codes [contributed by Kelly Gillilan]:
Invisible Team: 397BFFA5
Mirror Matches:
Washington 5B7FBFA3 Denver CFBFF7A0 Indianapolis 43AFFEAC Miami 46AFFDAB Cleveland 49AFFBA9 L.A. 969FDFA5 San Francisco 9C3F7FA5 Dallas 63AEFFA5 New York 269DFFA1 Chicago 697BFFA5 Minnesota AC37FFA9 ------------------------------------------------------------------------------ 11. Stage select in Penguin Wars:
At the character select screen, pick the character, then press L+B, then press A and [START]. ------------------------------------------------------------------------------ 12. Some interesting passwords for QBillion: WALL,IDEA,NOON ------------------------------------------------------------------------------ 13. Some interesting codes in Shanghai:
MAN - tough level REV - reversed tiles STF - credits ------------------------------------------------------------------------------ 14. Invisible opponents in SoccerMania:
At the title screen, press UUDDLRLRBA, then press [START] ------------------------------------------------------------------------------ 15. Passwords for Korodice:
1234 1234 1234 1234 A ** A *** A * * A * B * B * B ** B * * C ** C *** C ** C ** D D * D ** D ------------------------------------------------------------------------------ 26. Rolan's Curse:
QKMTTQHP (fire wand/magic axe) FRTTTGTP (sword/power crystal) at maximum power, only 25 sword hits to kill Barius. [Check these passwords again - I have information that they don't work] ------------------------------------------------------------------------------ 27. Selected paswords for Navy Blue:
65:MVCROEOX (CRUISER) 89:YLNFEMHQ (TARTAN) ??:KAFSKYLG (TOMCAT) 73:MBZRLYOC (SEA SPARROW) ??:YLNYDMIS (CARRIER) ??:FLTHVMXP (TRIDENT) 81:MUDLTEOH (TOMAHAWK) ??:FKMWCMHK (FANTOM) ??:FLTCWMHN (FINALE) ------------------------------------------------------------------------------ 28. Final boss in Bionic Commando:
1. Beat the game normally. 2. Wait for credits to scroll by. 3. When "The End" appears, hold UP+LEFT+SELECT+A 4. Enter initials and press A 5. Play as Goro!
Playing as Goro, hold A+B and then press DOWN. Goro [you] will disappear and the time will go much faster. Your opponent will be constantly repeating same move and won't be able to hit you.
These cheats were contributed by Jim Hsu and Timothy A. Meushaw ------------------------------------------------------------------------------ 30. Bill and Ted's level passwords:
2: MC BAIN 3: MILHOUSE 4: CMBURNS 5: PRINCESS ------------------------------------------------------------------------------ 32. Passwords for Prince of Persia:
A password is an 8-digit number abcdefgh. The first 3 digits (abc) are check-digits, the next one (d) codes the number of lives, the next two (ef) code the minutes left and the last two (gh) designate the level. How to construct your own password:
1. Choose your level and jot it down as two digits and reverse. Example: choose level 8 and write down 80. 2. Choose the number of minutes left and write it down in two digits, reverse, and append it to the left of the level. Example: choose 59 minutes, which gives 9580. 3. Choose the number of lifes (1 digit) and append it to the left. Example: choose 7 lifes to obtain 79580. 4. Call the result DEFGH and construct ABC as follows: C = G + H (subtract 10 if necessary) B = E + F (subtract 10 if necessary) A = C + D (subtract 10 if necessary) This way the 8-digit number ABCDEFGH is obtained. Example: C = 8 + 0 = 8 B = 9 + 5 = 4 A = 8 + 7 = 5 The result is 54879580. 5. Generate abcdefgh from ABCDEFGH by substituting each digit according to the table at the bottom. In our example 54879580 becomes the password 01928095 which is good for 7 lifes and 59 minutes on level 8. Table: FROM 0 1 2 3 4 5 6 7 8 9 INTO 5 4 7 6 1 0 3 2 9 8 ------------------------------------------------------------------------------ 33. Speedy Gonzales passwords:
Pause the game, then hit select 16 times. A box should appear over lives, time, or coins. Using A and B buttons you can increase all three to their maximum. This is available on each level. ------------------------------------------------------------------------------ 36. Monster Max passwords: 4.0 -8?-35R- 5.0 273?35RZ 6.0 JZVHMV3D 7.0 L5VP79N7 (This is actually 6.3, just use the lift to get to 7.0) 8.0 PL1H17P- (The 1s may be Is, I'm not sure) 9.0 MQLYTY2D 0.0 -J#X5DKP (Probably last level. Only one stage. Haven't finished.) ------------------------------------------------------------------------------
************************* Other cheats, passwords, etc. **********************
Adventure Island : Stage Select : RLRLABAB at the title screen Adventure Island 2 : Power Up : 0894 Amazing Penguin : Level 37 : 916328 Amazing Tater : Floor 3 : YBTF5ZZFT2 Amida : Passwords : TLKSS, LEIQX, VOTAJ Atomic Punk : Level 50 : B0MNDPBL3NCB3L2H2DJJ Avenging Spirit : Expert mode : U+A+B at the title screen Batman : Sound Test : U+R+START at the title screen Battle Bull : Level 48 : $F** BattleToads 2 : 5 toads : Holding D+A+B press [START] Boomer's Adventure : Level 55 : ANCIENT Boxxle : Lvl 11, Rm 8 : Q*HT * = Spade Boxxle 2 : Level 5 : 0K84 Brainbender : Level 5 : 3081 Bubble Bobble : Level 100 : KZ5J : Stage Select : KGBJ, then use L to select level Bugs Bunny : Level 79 : XHO2 Bugs Bunny 2 : Level 27 : KING Burai Fighter Deuxe : Level 5 : DKLF Catrap : Level 100 : R61H Chase HQ : Stage Select : Holding D+A+B press [START] Contra : Extra Lives : UUDDLRLRABAB[SELECT][START] Cyraid : Last Level : RUGGER Dead Heat Scramble : Stage Select : BBBBBBBBAAAAAAAA then B one less time : : than the number of wanted level Deadalian Opus : Stage Select : ZEAL Dick Tracy : Level 5 : 56115 Extra Bases : 7W 0L : 2CCZ Final Fantasy Leg. I : Sound Test : D+[START]+B at the title screen [?] Final Fantasy Leg. II : Sound Test : [SELECT]+B+[START] at title screen Fish Dude : Stage C-3 : SE Fist Of The North Star: Last Level : XKP72QNVHRJGU5 Flappy Special : ? : AK00 Flash : Level 13 : FUNHOUS Fortified Zone : Level 4 : 1122 Gargoyle's Quest : Last Level : SWXE-CBFJ Godzilla : Last Level : JXRB7K&948HPD32#JN GO! GO! Tank : Cheat Mode : LURULLURULUL[START] at title screen Hong Kong : Test Mode : A+B+[START] at the second screen : Sound Test : B+[START] at the second screen : End Screen : A+[START] at the second screen Hunt for Red October : Stage Select : B[SELECT]LR[START] at title screen Hyper Loderunner : Level Select : Enter QM-0388 as passcode Kirby's Dream Land : Cheat Mode : D+[SELECT]+B Lock & Chase : ? : Press AABBABB at the title screen Mercenary Force : Stage Select : Holding U+[SELECT]+A+B press [START] Navy Blue : End : FLTCWMHN Ninja Boy : Stage Select : UUDDABAB, holding A press [START] : Continue : Holding A press [START] Operation C : Stage Select : UUDDLRLRBABA[START] at full title screen Pitman : Stage Select : Q16KXW [Stage 95] Power Mission : Level 11 : LRDMR1 Prince of Persia : Final Battle : 71196464 Q Billion : Stage Select : TOIL Raging Fighter : Plr vs. Plr : UUDDLRLRB, then A for dk., B for normal Roger Rabbit : Level 6 : RTJBWW43 Rolan's Curse : End : PQRJLNPC Snoopy's Magic Show : Level 58 : V5YO Snow Bros. Jr. : Stage Select : Holding U+[SELECT]+B press start at : : the title screen Solomon's Club : Level 4-10 : QDDHSY8 Spanky's Quest : Stage Select : 0119 Spud's Adventure : Stage Select : BANCHOU Star Trek : Planet Killer: 3516.7 Super Mario Land 2 : Easy Mode : [SELECT] at the pipe screen Tail Gator : Last Area : 8093 TMNT : Extra Life : Pause game, then UUDDLRLRBA[START] : Bonus Games : Holding A+B+[SELECT] press [START] at : : the config screen [?] Tetris : Expert Mode : D+[START] at the title screen Turrican : Stage Select : Holding [SELECT] press [START] at the : : title screen
************************* IV. List of the best games *************************
This list is compiled based on the ratings and reviews I got from various sources. The fact that some game is in the list doesn't necessarily mean that it is the best game for you; it just means that this game is worth checking out. I put asterisk (*) next to my personal favorites. For the current information about the best games, you can refer to the "Nick's GameBoy Game Ratings List". It also seems to be biased, but let's hope that it will look better when more people contribute to it. Information about obtaining this list is in the "GB Resources on the Net" part of this FAQ list.
1. RPGs:
*Final Fantasy Legend | *Final Fantasy Adventure (2MBit) +-----> These seem to be everybody's *Final Fantasy Legend 2 (2MBit) | favorites. Final Fantasy Legend 3 (4MBit?)| Zelda: Link's Awakening (4MBit)
*Metroid II SuperMarioLand II (4MBit) *Castlevania II: Belmont's Revenge *Batman *TMNT: Fall of the foot Clan *Operation C Mega Man 1,2,3 BattleToads Gargoyle's Quest
4. 3D Games:
*Altered Space (platform game) Faceball 2000 (shoot-em-up)
5. Sport Games:
Jack Nicklaus Golf F-1 Race
6. Logic/Strategy Games:
*Shanghai *Tetris Chessmaster [watch for revision, there are two of them] *Spot 4-in-1 packs 1 and 2 Dr. Mario Ishido
7. StreetFighter clones:
Mortal Kombat Raging Fighter
8. Classical Arcade games:
Asteroids Missile Command Centipede Pacman
9. Flight Simulators:
Turn and Burn Top Gun
******************************* V. Game Genie ********************************
1. How it works?
GameGenie allows you to substitute some of the codes in the cartridge ROM with your own codes. For example, you can substitute the default number of lives with your own number. GameBoy GameGenie allows to substitute up to three codes.
2. Where to get the codes?
GameBoy GameGenie codes are available through anonymous FTP at
ftp.netcom.com directory /pub/vidgames/gamegenie
3. What is the meaning of the digits in GameGenie code for GameBoy?
* All digits are in hexadecimal system
GameBoy GameGenie Code: DD2-103-???
DD - Data Byte 0,1,2,3 - Address, reads as 3210 ??? - Meaning of these digits is unknown. It is suspected that they represent the ROM paging register, but no information is available.
Example: 3D2-ABF-3BE - Set 3Dh (DEC A command) at address F2ABh
4. Some commonly used Z80 instructions with their codes:
Code(s): Instruction: Common Usage: 3Eh xxh - LD A,xxh Load default number of lives (energy,ammo,etc.) 3Dh - DEC A Decrease number of lives (energy,ammo,etc.) 3Ch - INC A Increase number of lives (energy,ammo,etc.) 00h - NOP DO NOTHING (set this instead of 3Dh)
Some games exist in several different versions. Although these versions look exactly the same, the actual program codes differ. Therefore, while some GameGenie codes work with one version of the cartridge, they aren't guaranteed to work with other versions.
**************************** VI. Various Questions ***************************
1. Are there any GameBoy emulators for the personal computers?
YES, there is a GameBoy emulator written by me, Marat Fayzullin. It is called Virtual GameBoy and can be obtained from
The Virtual GameBoy is portable. Its distribution includes C source code which can be compiled on any computer [given that there are system-dependent drivers for this computer] and a set of sample drivers for Unix/XWindows. For more information, refer to documentation at above-mentioned WWW. There is also a GameBoy-look-alike emulator for the Commodore Amiga called ToyBoy. This emulator can be obtained via FTP from AmiNet sites:
Unfortunately, this package is incomplete amd HAS NOTHING TO DO with the real GameBoy. It was stolen from a UK-based company called Argonaut which does hardware and software development for Nintendo. According to Argonaut's managing director Jez San, ToyBoy was an in-house emulator written to see how difficult it would be to program GameBoy games. Since its authors knew nothing about internals of the real GameBoy when they were writing the emulator, ToyBoy is completely incompatible with GameBoy.
2. Is it possible to build a backlight into GameBoy?
A Japanese company sells a kit to add the EL-backlight to GameBoy. The kit costs 5000yen. (Information provided by Cinnichiro Ichise [ichise@mica.semicon.sony.co.jp])
3. Are there any game copiers for GameBoy?
There is a SmartCard copier allowing to download data from GameBoy cards to PC via parallel port and store up to 4 games in a 4MBit flash-RAM cartridge. There are said to be GameBoy adaptors for MultiGameDoctorII, MultiGameHunter, SuperWildCard, and SuperComPro. Also, there is a device allowing to play games stored on credit card-like magnetic cards which is produced in Japan and isn't sold in U.S.
4. MultiGame cartridges for GameBoy:
Yes, these cartridges are at least half-illegal because their producers violate copyright law. Yes, these things exist for GameBoy. At present time, there are four kinds of them: 48in1, 64in1, 86in1 and 105in1 (although there were rumors about 200in1 and even 1500in1 cartridges. The latter is said to be 15-20 cm long). They all seem to contain the same basic set of games most of which are either old Nintendo products (like Alleyway or Tennis) or low-quality games from other companies with a couple of good games added. Number of games in such a cartridge is actually SMALLER than the number written on the box because some games are present in two or three copies (with a number of lives and other things changed). For example, 64in1 cartridge contains only about 48 DISTINCT games. At least 27 of them can be classified as "logic" or "strategy" games. There were many requests to list games multigame cartridges contain. So, here is a list of games how it appears in a menu of a 105in1 cartridge. Other multigame cartridges contain subset of games listed below. Notice the large number of japanese titles and repetitions. There are also some titles which actually correspond to the same game.
turtle ninja bouken jima super mario land motocross penguin land kid kiki mickey mouse crocodile dr. mario solomons club head on dr mario ishido battle city bouken tennis volley fire boxing trump boy klax bubble ghost master karateka othello puzzle boy hong kong tetris minisweeper heiankyo alien bouken 3 flipull hyper loderunner amida yakuman match mania pala medes world bowling loopz bouken 4 alleyway koro dice puzzle road spot castelian dragon slayer 1 space invader snake war bouken 5 flappy special pipe dream koi wa kakehiki bouken 6 pitman tasmania story soukoban 2 shanghai kinkong escape arkanoil ls caste star gate bouken 7 super kid super turtle super mario go tank bouken 8 spec mouse big ghost excite bike penguin egg spec turtle adventure 2 tank kiki mouse small ghost motor bike adventure big penguin speed runner bom bom alley 1992 castelian thunder force luck boy adventure 4 sp turtle mario boy adventure 5 loder runner sp alley sp motocross adventure 6 sp invader sp kid kiki easy tasmania adventure 7 turtle ii sp mario gogo tank adventure 8 sp mouse adventure island sp penguin happy boy happy ghost bouken boy sp tasmania
5. Using GameGenie with multigame cartridges:
No, GameGenie DOES NOT WORK with multigame cartridges.
6. GameBoy clones:
There seem to be several GameBoy clones produced in Asia. Two of them are called Sunny and WonderBoy. The only difference is the name printed on the case. This information was supplied by Simon Lai. The Russian GameBoy clone is called Bitman2000, if it is a clone and not a real GameBoy distributed in Russia under that name.
7. Japanese cartridges:
These are cartridges which are not available in U.S., although you can find them if you are lucky. Following descriptions of japanese cartridges were prepared by Mark Kaufman.
Another Japanese cart that should be sold over here. It's better than 90% of all GB games.
8. Where to get parts to repair GameBoy?
Mark Kaufman found address of the company selling replacement parts for GameBoy [as well as Sega AC adapters and Atari parts]. Here is their phone number and a list of GameBoy parts they carry:
MCM Electronics TOLL-FREE: 1-800-543-4330 FAX: 1-513-434-6959 VOICE: 1-513-434-0031 M-F: 7AM-8PM EST Sat: 9AM-6PM EST
#83-2285 $3.50 Gameboy Type 32 Pin Connector (replace worn or corroded cartridge jack inside GB) #83-1570 $1.49 Controller Replacement Pads (set of three) #81-1605 $7.95 Schematic Diagrams (THIS should be interesting! =))
Game Bit Drivers (fit tamper resistant star screws): #22-1145 $9.95 Small bit for GB cartridge #22-1150 $9.95 Large bit for GB battery packs
9. Some time ago, there was a preview of a 3D vectored game for GB called "Lunar Chase" in Nintendo Power magazine. What happened with this game?
According to Nintendo, the game was cancelled :(. This information was obtained from Nintendo hotline [1-800-255-3700 in USA].
********************** VII. Programming, Hardware, etc. *********************
Information about GameBoy hardware is extremely hard to find. Most of it is incomplete, uncertain and vague. If you have any information [especially about things listed in "Unanswered Questions" section], PLEASE, email it to fms@wam.umd.edu. The following information is mostly based on a document by Dr.Pan of Anthrox, but also includes some results of research done by Peter Knight and myself.
1. Development tools for GameBoy:
There are very few publically accessible development tools available for GB. Some of them are:
* SmartCard copier allows to download the code from GB cartridges into PC and store up to 4 cartridges in a special 512kB flash-ROM card. * Logical analyzers allowing to trace various signals in GB circuitry are also very useful for hacking. * SNES Magic Disassembler by Dr.Pan is written primarily for SNES, but it also allows to disassemble, explore, and change GB code. SMD is a shareware and it runs on Amiga. * Another GB disassembler for PC is written by HeroZero. * Virtual GameBoy emulator by me is a portable emulator written in C. The distribution version runs on Unix/X systems, but with proper drivers VGB can run on just about anything, given that your machine is fast enough. VGB also includes a small disassembler for GB code.
2. GameBoy cartridge pinouts [not complete]: ------------------------------------------------------------------------------ Pin Function ------------------------------------------------------------------------------ 1 Vcc [+5V] 2 ? Connected on Gameboy, but not used on GamePaks. 3 /RESET 4 /WR 5 ? Used by paging PAL on high capacity GamePaks. 6-20 A0-A14 21 /CS 22-29 D0-D7 30 /RD 31 ? Connected on Gameboy, but not used on Game-Paks. 32 GND ------------------------------------------------------------------------------
3. GameBoy CPU:
As it appears, the CPU used in GameBoy is not exactly Z80. Some of Z80 instructions and registers are missing while others are added:
* The "shadow" set of registers [BC',DE',HL',AF'] and the index registers [IX,IY] are missing and, consequently, there are no DD and FD opcode tables.
* I/O ports are gone and so are all IN/OUT opcodes.
* HALT is interrupted even when interrupts are disabled.
* Following Z80 opcodes are changed: ------------------------------------------------------------------------------ Code Z80 operation GameBoy operation ------------------------------------------------------------------------------ 08 xx xx EX AF,AF' LD (word),SP Save SP at given address 10 xx DJNZ offset STOP Meaning unknown 22 LD (word),HL LD (HLI),A Save A at (HL) and increment HL 2A LD HL,(word) LD A,(HLI) Load A from (HL) and increment HL 32 LD (word),A LD (HLD),A Save A at (HL) and decrement HL 3A LD A,(word) LD A,(HLD) Load A from (HL) and decrement HL D3 OUTA (byte) No operation D9 EXX RETI Enable interrupts and return DB INA (byte) No operation DD Prefix DD No operation E0 xx RET PO LD (byte),A Save A at (FF00+byte) E2 JP PO,word LD (C),A Save A at (FF00+C) E3 EX HL,(SP) No operation E4 CALL PO,word No operation E8 xx RET PE ADD SP,offset Add signed offset to SP EA xx xx JP PE,word LD (word),A Save A at given address EB EX DE,HL No operation EC CALL PE,word No operation F0 xx RET P LD A,(byte) Load A from (FF00+byte) F2 JP P,word No operation F4 CALL P,word No operation F8 xx RET M LDHL SP,offset Load HL with SP + signed offset FA xx xx JP M,word LD A,(word) Load A from given address FC CALL M,word No operation FD Prefix FD No operation ------------------------------------------------------------------------------
4. GameBoy memory map: --------------------------- FFFF | 32kB ROMs are non-switchable and occupy I/O ports + internal RAM | 0000-7FFF are. Bigger ROMs use one of two --------------------------- FF00 | different bank switches. The type of a Internal RAM | bank switch can be determined from the --------------------------- C000 | internal info area located at 0100-014F 8kB switchable RAM bank | in each cartridge. --------------------------- A000 | 16kB VRAM | MBC1 (Memory Bank Controller 1): --------------------------- 8000 | Writing a value into 2000-3FFF area will 16kB switchable ROM bank | select an appropriate ROM bank at --------------------------- 4000 | 4000-7FFF. Writing a value into 4000-5FFF 16kB ROM bank #0 | area will select an appropriate RAM bank --------------------------- 0000 | at A000-C000. | | MBC2 (Memory Bank Controller 2): | Writing a value into 2100-21FF area will | select an appropriate ROM bank at | 4000-7FFF. RAM switching is not provided.
5. Internal information area:
The internal information area is located at 0100-014F in each cartridge. It contains following values:
0100-0103 A sequence of bytes 00 C3 xx xx where last two bytes contain the starting address of a cartridge [lower byte first]. The first two bytes of this sequence can be used as a "magic number" to recognize GameBoy cartridges. When GameBoy starts, the control is passed to address 0100 and then the sequence is interpreted as NOP; JP . 0105-0133 Nintendo character area: CE ED 66 66 CC 0D 00 0B 03 73 00 83 00 0C 00 0D 00 08 11 1F 88 89 00 0E DC CC 6E E6 DD DD D9 99 BB BB 67 63 6E 0E EC CC DD DC 99 9F BB B9 33 3E 0134-0143 Title of the game in ASCII terminated by zeroes 0144-0146 Not used 0147 Cartridge type: 0 - ROM ONLY 3 - ROM+MBC1+RAM+BATTERY 1 - ROM+MBC1 5 - ROM+MBC2 2 - ROM+MBC1+RAM 6 - ROM+MBC2+BATTERY 0148 ROM size: 0 - 256kBit = 32kB = 2 banks 1 - 512kBit = 64kB = 4 banks 2 - 1MBit = 128kB = 8 banks 3 - 2MBit = 256kB = 16 banks 4 - 4MBit = 512kB = 32 banks 0149 RAM size: 0 - None 1 - 16kBit = 2kB = 1 bank 2 - 64kBit = 8kB = 1 bank 3 - 256kBit = 32kB = 4 banks 0150-0151 Manufacturer code: 3301 - Nintendo 7901 - Accolade A400 - Konami 014C Version number 014D Complement check 014E-014F Checksum [higher byte first] produced by adding all bytes of a cartridge except for two checksum bytes together and taking two lower bytes of the result.
6. Video controller:
Main GameBoy screen buffer [aka background] consists of 256x256 pixels or 32x32 tiles [8x8 pixels each]. Only 160x144 pixels can be displayed on the screen. Registers SCROLLX and SCROLLY hold the coordinates of background to be displayed in the left upper corner of the screen. Background wraps around the screen i.e. when part of it goes off the screen, it appears on the opposite side. An area of VRAM known as Background Tile Table contains the numbers of tiles to be displayed. It is organized as 32 rows of 32 bytes each. Each byte contains a number of a tile to be displayed. Tile patterns are taken from the Tile Pattern Table located either at 8000-8FFF or 8800-97FF. In the first case, patterns are numbered with unsigned numbers from 0 to 255 [i.e. pattern #0 lies at address 8000]. In the second case, patterns have signed numbers from -128 to 127 [i.e. pattern #0 lies at address 9000]. The Tile Pattern Table address for the background can be selected via LCDCONT register. Besides background, there is also a "window" overlaying the background. The window is not scrollable i.e. it is always displayed starting from its left upper corner. The location of a window on the screen can be adjusted via WNDPOSX and WNDPOSY registers. Screen coordinates of the top left corner of a window are WNDPOSX-7,WNDPOSY. The tile numbers for the window are stored in the Window Tile Table in the same way as background tiles are stored in the Background Tile Table. The tile patterns are taken from the table at 8800-97FF and therefore have unsigned numbers. Both background and window can be disabled or enabled separately via bits in the LCDCONT register. There is also a special bit allowing to make window "transparent". When window is transparent, pixels of color #0 are not being displayed.
As it was said before, there are two Tile Pattern Tables at 8000-8FFF and at 8800-97FF. The first one can be used for sprites and the background. Its tiles are numbered from 0 to 255. The second table can be used for the background and the window display and its tiles are numbered from -128 to 127. GameBoy video controller can also display up to 40 sprites either in 8x8 or in 8x16 mode. Sprite patterns have the same format as tiles, but they are taken from the Sprite Pattern Table located at 8000-8FFF and therefore have unsigned numbers. Sprite attributes reside in the Sprite Attribute Table [aka OAM] at FE00-FE9F. OAM is divided into 40 4-byte blocks each of which corresponds to a sprite. Blocks have the following format:
Byte0 Y position on the screen Byte1 X position on the screen Byte2 Pattern number 0-255 [notice that unlike tile numbers, sprite pattern numbers are unsigned] Byte3 Flags: Bit7 Priority Sprite is displayed in front of the window if this bit is set to 1. Otherwise, sprite is shown behind the window but in front of the background. Bit6 Y flip Sprite pattern is flipped vertically if this bit is set to 1. Bit5 X flip Sprite pattern is flipped horizontally if this bit is set to 1. Bit4 Palette number Sprite colors are taken from OBJ1PAL if this bit is set to 1 and from OBJ0PAL otherwise.
7. GameBoy Sound:
There are two sound channels connected to the output terminals SO1 and SO2. There is also a input terminal Vin connected to the cartridge. It can be routed to either of both output terminals. GameBoy circuitry allows produces sound in four different ways:
1. Quadrangular wave patterns with sweep and envelope functions 2. Quadrangular wave patterns with envelope functions 3. Voluntary wave pattern 4. White noise
These four sounds can be controlled independantly and then mixed separately for each of the output terminals.
8. GameBoy I/O ports:
I/O ports are mapped to memory locations in FF00-FFFF area: ------------------------------------------------------------------------------ FF00 -- JOYPAD [RW] Joypad port Bit5 Bit4 | In order to scan the keys, output 0 into either Bit4 Bit3 DOWN START | or Bit5 of JOYPAD, wait for some time and read JOYPAD. Bit2 UP SELECT | Bits 0-3 will be set to zeroes if corresponding Bit1 LEFT B | buttons are pressed. Bits 6 and 7 are not used. Bits Bit0 RIGHT A | 0-3 are connected to input lines P10-P13. Bits 4 and 5 | are connected to ouput lines P14 and P15.
Example: ; Routine finding which buttons were pressed since the last check LD A,20h ; Set 0 at the output line P14 LD (FF00h),A ; LD A,(FF00h) ; Read JOYPAD several times to accomodate the noise LD A,(FF00h) ; CPL ; Bits 0-3 are now 1s if corresponding buttons pressed AND 0Fh ; Extract lower 4 bits carrying button status... SWAP A ; ...and move them into upper for bits LD B,A ; At this point: B = START.SELECT.B.A.x.x.x.x LD A,10h ; Set 0 at the output line P15 LD (FF00h),A ; LD A,(FF00h) ; Read JOYPAD several times to accomodate the noise LD A,(FF00h) ; LD A,(FF00h) ; LD A,(FF00h) ; LD A,(FF00h) ; LD A,(FF00h) ; CPL ; Bits 0-3 are now 1s if corresponding buttons pressed AND 0Fh ; Extract lower 4 bits carrying buttons' status... OR B ; ...and combine them with 4 other button status bits LD D,A ; At this point: D = START.SELECT.B.A.DOWN.UP.LEFT.RIGHT LD A,(FF8Bh) ; Read old button status from RAM XOR D ; Set 1s for buttons whose status has changed AND D ; Extract buttons which were *pressed* since last check LD (FF8Ch),A ; Save information of those buttons LD A,D ; Update button status in RAM LD (FF8Bh),A ; LD A,30h ; Set 1s at both P14 and P15 lines LD (FF00h),A ; [probably to reset the circuitry]
------------------------------------------------------------------------------ FF01 -- SIODATA [RW] Serial I/O Data ----------------------------------------------+---------------+--------------- FF02 -- SIOCONT [RW] Serial I/O Control | when set to 1 | when set to 0 Bit7 Transfer start flag | START | NO TRANSFER Bit0 Serial I/O clock select | INTERNAL | EXTERNAL ----------------------------------------------+---------------+--------------- FF04 -- DIVIDER [RW] Divider [meaning unknown] ------------------------------------------------------------------------------ FF05 -- TIMECNT [RW] Timer Counter This register contains constantly increasing number. The timer interrupt occurs when this register overflows. ------------------------------------------------------------------------------ FF06 -- TIMEMOD [RW] Timer Modulo The contents of TIMEMOD are loaded into TIMECNT every time TIMECNT overflows. ----------------------------------------------+---------------+--------------- FF07 -- TIMCONT [RW] Timer Control | when set to 1 | when set to 0 Bit2 Start/Stop timer | COUNTING | STOPPED Bit1-0 Timer clock select: 00 - 4096Hz 01 - 262144Hz 10 - 65536Hz 11 - 16384Hz ----------------------------------------------+---------------+--------------- FF0F -- IFLAGS [RW] Interrupt Flags | when set to 1 | when set to 0 Bit4 Transition High->Low on pins P10-P13 | OCCURED | NO Bit3 End of serial I/O transfer | OCCURED | NO Bit2 Timer overflow | OCCURED | NO Bit1 LCD controller interrupt [see LCDSTAT] | OCCURED | NO Bit0 LCD vertical blanking impulse | OCCURED | NO ----------------------------------------------+---------------+--------------- FF10 -- SNDREG10 [RW] Sweep [Sound Mode #1] Bit6-4 Sweep time: 000: SWEEP OFF 010: 15.6ms 100: 31.3ms 110: 46.9ms 001: 7.8ms 011: 23.4ms 101: 39.1ms 111: 54.7ms Bit3 Frequency increase[0]/decrease[1] Bit2-0 Number of shifts ------------------------------------------------------------------------------ FF11 -- SNDREG11 [RW] Sound Length/Pattern Duty [Sound Mode #1] Bit7-6 Wave Pattern Duty [only these bits can be read]: 00: 12.5% 01: 25% 10: 50% 11: 75% Bit5-0 Length of sound data ------------------------------------------------------------------------------ FF12 -- SNDREG12 [RW] Control [Sound Mode #1] Bit7-4 Initial value of envelope Bit3 Envelope up[1]/down[0] Bit2-0 Number of envelope sweep ------------------------------------------------------------------------------ FF13 -- SNDREG13 [W] Frequency Low [Sound Mode #1] Lower 8 bits of the 11bit frequency. Higher 3 bits are in SNDREG14. ------------------------------------------------------------------------------ FF14 -- SNDREG14 [RW] Frequency High [Sound Mode #1] Bit7 When 1 is written into this bit, sound restarts Bit6 Counter/Consecutive selection [only this bit can be read] Bit2-0 Higher 3 bits of the 11bit frequency ------------------------------------------------------------------------------ FF16 -- SNDREG21 [RW] Sound Length/Pattern Duty [Sound Mode #2] Bit7-6 Wave Pattern Duty [only these bits can be read]: 00: 12.5% 01: 25% 10: 50% 11: 75% Bit5-0 Length of sound data ------------------------------------------------------------------------------ FF17 -- SNDREG22 [RW] Control [Sound Mode #2] Bit7-4 Initial value of envelope Bit3 Envelope up[1]/down[0] Bit2-0 Number of envelope step ------------------------------------------------------------------------------ FF18 -- SNDREG23 [W] Frequency Low [Sound Mode #2] Lower 8 bits of the 11bit frequency. Higher 3 bits are in SNDREG24. ------------------------------------------------------------------------------ FF19 -- SNDREG24 [RW] Frequency High [Sound Mode #2] Bit7 When 1 is written into this bit, sound restarts Bit6 Counter/Consecutive selection [only this bit can be read] Bit2-0 Higher 3 bits of the 11bit frequency ------------------------------------------------------------------------------ FF1A -- SNDREG30 [RW] Control [Sound Mode #3] Bit7 Sound on[1]/off[0] ------------------------------------------------------------------------------ FF1B -- SNDREG31 [RW] Sound Length [Sound Mode #3] ------------------------------------------------------------------------------ FF1C -- SNDREG32 [RW] Output Level [Sound Mode #3] Bit6-5 Output Level: 00: MUTE 01: 100% 10: 50% 11: 25% ------------------------------------------------------------------------------ FF1D -- SNDREG33 [W] Frequency Low [Sound Mode #3] Lower 8 bits of the 11bit frequency. Higher 3 bits are in SNDREG34. ------------------------------------------------------------------------------ FF1E -- SNDREG34 [RW] Frequency High [Sound Mode #3] Bit7 When 1 is written into this bit, sound restarts Bit6 Counter/Consecutive selection [only this bit can be read] Bit2-0 Higher 3 bits of the 11bit frequency ------------------------------------------------------------------------------ FF20 -- SNDREG41 [RW] Sound Length/Pattern Duty [Sound Mode #4] Bit5-0 Length of sound data ------------------------------------------------------------------------------ FF21 -- SNDREG42 [RW] Control [Sound Mode #4] Bit7-4 Initial value of envelope Bit3 Envelope up[1]/down[0] Bit2-0 Number of envelope step ------------------------------------------------------------------------------ FF22 -- SNDREG43 [RW] Polynomial Counter [Sound Mode #4] Bit7-4 Shift clock frequency for the counter 0000: Dividing ratio of frequencies / 2 0001: Dividing ratio of frequencies / 2^2 0010: Dividing ratio of frequencies / 2^3 .... .... 1101: Dividing ratio of frequencies / 2^14 1100: Prohibited 1111: Prohibited Bit3 Number of steps: 7 [1]/15 [0] Bit2-0 Dividing ratio of frequences 000: f*2 010: f/2 100: f/4 110: f/6 where f = 4.194304Mhz/8 001: f*1 011: f/3 101: f/5 111: f/7 ------------------------------------------------------------------------------ FF23 -- SNDREG44 [RW] Frequency High [Sound Mode #4] Bit7 When 1 is written into this bit, sound restarts Bit6 Counter/Consecutive selection [only this bit can be read] ------------------------------------------------------------------------------ FF24 -- SNDREG50 [RW] Channel and Volume Control Bit7 Vin -> SO2 on[1]/off[0] Bit6-4 Volume on SO2 Bit3 Vin -> SO1 on[1]/off[0] Bit2-0 Volume on SO1 ------------------------------------------------------------------------------ FF25 -- SNDREG51 [RW] Sound Output Terminal Selector Bit7 Sound 4 -> SO2 | Bit6 Sound 3 -> SO2 | Bit5 Sound 2 -> SO2 | SO1 and SO2 are two sound outputs connected to the Bit4 Sound 1 -> SO2 | headphones. Vin is an input terminal in the cartridge Bit3 Sound 4 -> SO1 | slot. Bit2 Sound 3 -> SO1 | Bit1 Sound 2 -> SO1 | Bit0 Sound 1 -> SO1 | ----------------------+------------------------------------------------------- FF26 -- SNDREG52 [RW] Sound ON/OFF Bit7 All sound on[1]/off[0] Bit3 Sound 4 on[1]/off[0] Bit2 Sound 3 on[1]/off[0] Bit1 Sound 2 on[1]/off[0] Bit0 Sound 1 on[1]/off[0] ----------------------------------------------+---------------+--------------- FF40 -- LCDCONT [RW] LCD Control | when set to 1 | when set to 0 Bit7 LCD operation | ON | OFF Bit6 Window Tile Table address | 9C00-9FFF | 9800-9BFF Bit5 Window display | ON | OFF Bit4 Tile Pattern Table address | 8000-8FFF | 8800-97FF Bit3 Background Tile Table address | 9C00-9FFF | 9800-9BFF Bit2 Sprite size | 8x16 | 8x8 Bit1 Color #0 transparency in the window | SOLID | TRANSPARENT Bit0 Background display | ON | OFF ----------------------------------------------+---------------+--------------- FF41 -- LCDSTAT [RW] LCD Status | when set to 1 | when set to 0 Bit6 Interrupt on scanline coincidence | ON | OFF Bit5 Interrupt on controller mode 10 | ON | OFF Bit4 Interrupt on controller mode 01 | ON | OFF Bit3 Interrupt on controller mode 00 | ON | OFF Bit2 Scanline coincidence flag | COINCIDENCE | NO COINCIDENCE Bit1-0 LCD Controller mode: 00 - Horizontal blanking impulse [VRAM 8000-9FFF can be accessed by CPU] 01 - Vertical blanking impulse [VRAM 8000-9FFF can be accessed by CPU] 10 - OAM FE00-FE90 is accessed by LCD controller 11 - Both OAM FE00-FE90 and VRAM 8000-9FFF are accessed by LCD controller ------------------------------------------------------------------------------ FF42 -- SCROLLY [RW] Background Vertical Scrolling ------------------------------------------------------------------------------ FF43 -- SCROLLX [RW] Background Horizontal Scrolling ------------------------------------------------------------------------------ FF44 -- CURLINE [RW] Current Scanline This register contains the number of a screen line currently being scanned. It can take values 0-153 where 144-153 indicate the vertical blanking period. Writing into this register resets it. ------------------------------------------------------------------------------ FF45 -- CMPLINE [RW] Scanline Comparison When contents of CURLINE are equal to contents of CMPLINE, scanline coincidence flag is set in the LCD status register and an interrupt may occur. ------------------------------------------------------------------------------ FF47 -- BGRDPAL [W] Background Palette Bit7-6 Palette for color #3 | Bit5-4 Palette for color #2 | 00 ------- 01 ------- 10 -------> 11 Bit3-2 Palette for color #1 | lightest darkest Bit1-0 Palette for color #0 | ------------------------------+----------------------------------------------- FF48 -- OBJ0PAL [W] Sprite Palette #0 Bit7-6 Palette for color #3 | Bit5-4 Palette for color #2 | 00 ------- 01 ------- 10 -------> 11 Bit3-2 Palette for color #1 | lightest darkest Bit1-0 Palette for color #0 | ------------------------------+----------------------------------------------- FF49 -- OBJ1PAL [W] Sprite Palette #1 Bit7-6 Palette for color #3 | Bit5-4 Palette for color #2 | 00 ------- 01 ------- 10 -------> 11 Bit3-2 Palette for color #1 | lightest darkest Bit1-0 Palette for color #0 | ------------------------------+----------------------------------------------- FF4A -- WNDPOSY [RW] Window Y Position WNDPOSY may assume values 0-143. It determines the vertical position of the left upper corner of a window on the screen. ------------------------------------------------------------------------------ FF4B -- WNDPOSX [RW] Window X Position WNDPOSX may assume values 7-166. It determines the horizontal position of the left upper corner of a window on the screen. The real position is WNDPOSX-7. ------------------------------------------------------------------------------ FF46 -- DMACONT [W] DMA Transfer Control Writing to this register will cause a DMA transfer into OAM located at FE00-FE9F. The written value determines the source address in a following way: 00 -> 0000, 01 -> 0100, ... , 9A -> 9A00, ... The DMA transfer takes about 160 nanoseconds.
Example: ; Routine transferring 0400-049F into OAM DI ; Disable interrupts LD A,04h ; Transferring data from 0400h LD (FF46h),A ; Start DMA transfer LOOP: LD A,#40 ; Wait DEC A ; JR NZ,LOOP ; EI ; Enable interrupts
----------------------------------------------+---------------+--------------- FFFF -- ISWITCH [RW] Interrupt Enable/Disable | when set to 1 | when set to 0 Bit4 Transition High->Low on pins P10-P13 | ENABLED | DISABLED Bit3 End of serial I/O transfer | ENABLED | DISABLED Bit2 Timer overflow | ENABLED | DISABLED Bit1 LCD controller interrupt [see LCDSTAT] | ENABLED | DISABLED Bit0 LCD vertical blanking impulse | ENABLED | DISABLED ----------------------------------------------+---------------+---------------
Thanks to all people who sent their comments and contributed to this document! (list follows)
Dr.Pan of Anthrox - Excellent GameBoy hardware description Mark Kaufman - Cheats for Faceball 2000 and passwords Pipe Dream. Descriptions and ratings of some games. MCM Electrionics' phone numbers. Yi-Min Wei - Comments about software sections of the FAQ. Kelly Gillilan - Excellent list of cheats and passwords. Tecmo Bowl codes. CodeMasters' phone number. Peter Knight - Cartridge pinouts and a memory map. Codemasters' address. Jim Hsu - List of passwords and codes and MK cheat. Jez San [Argonaut] - Information about Argonaut's ToyBoy emulator. Timothy A. Meushaw - Mortal Kombat cheat. Robert Newman - Various cheats and codes. M. S. Manley - Maintaining GB mailing list and mail-server. G. L. Sicherman - Krusty's Fun House passwords. Jack Skipper - Sound test cheats for FFLI and FFLII. Andy Eddy - Maintaining FAQ archive at ftp.netcom.com. Simon Lai - Info on Thailand GB clones and 1500in1 cart. Josef Mollers - Info on GB cartridge pinouts. Herl Lindgreen - Prince of Persia password construction. G. L. Sicherman - Speedy Gonzales passwords. Jim Banks - Warioland cheat. Nick Paiement - Game ratings Leo Davidson - Monster Max passwords
If you have any information about GameBoy, feel free to send email to
Marat Fayzullin (FMS) fms@wam.umd.edu
1. Meaning of the last three digits of GameGenie code? 2. Pinouts of the GameBoy cartridges? 3. Connecting GameBoy to TV? 4. GameGenie codes not listed in the official updates? 5. Game cheats and passwords? 6. GameBoy emulators? 7. Classified listings of the games with ratings from 0 to 9? 8. Game Copiers for GameBoy? 9. "Generic" cartridges allowing to use reprogrammable ROM plugged into a socket or even a static RAM? 10. Pinouts of GameBoy's serial port? 11. etc. etc. etc.
* Reviews: Please, send your reviews of GB games. Rate four categories:
Graphics Sound Playability Overall
Give ratings from 0 to 9 for each of these categories. Also, classify the game [RPG, shoot-em-up, classic, etc.] and give information about the cartridge size and manufacturer. Games which get more than 2 ratings from different people, will be mentioned in the FAQ. I still couldn't collect enough of these raitings to come to any conclusions.
