gameboy dmg 01 lcd screen free sample

We still have our original game boy and several games that have been stored nicely in tiny plastic cases. Since it’s in bad shape, I wanted to get another one. Fortunately for us, they refurbish them. When it first premiered in the nineties, we had a great time playing with it. Compared to today, the graphics are old school on a black and white screen, but despite that, it’s no different than playing on a cellphone screen today except today’s is more colorful and defined. But playing them on a black and white makes it extra challenging. The sound is very good, and the games are still fun today and even more challenging than I’ve played on my cellphone. This year I gave my new refurbished one as a “fun” gift to my son and we’ve been playing Home Alone, Escape to New York, a game I finished and beat years ago. But now It is so hard, but still just as fun to play with. This original gameboy is a little and fun game system to play, and the games are worth it. Plus, there are so many different ones. Fortunately I kept all of them and they are still very playable. For example, we have the Home Alone-New York one, wheel of fortune game, Simpson’s, Nigel Mansell which is a car racing one, and kirby’s Dreamland to mention a few. If you are a fan of different game systems, I suggest you try this original game boy and enjoy the challenge of playing very fun but challenging games on it. It’s well worth it.

Instead of placing many off-the-shelf chips on the motherboard, Nintendo opted for a single chip to house (and hide) most of the components, including the CPU. This type of chip is called ‘System On Chip’ (SoC) and the one found on the GameBoy is referred to as DMG-CPU or Sharp LR35902

All graphics calculations are done by the CPU, and then the Picture Processing Unit or ‘PPU’ renders them. This is another component found inside DMG-CPU and it’s actually based on the predecessor’s PPU.

The picture is displayed on an integrated LCD screen, it has a resolution of 160×144 pixels and shows 4 shades of grey (white, light grey, dark grey and black). But since the original Gameboy has a green LCD, graphics will look greenish.

If you’ve read the NES article before, you may remember that the PPU was designed to follow the CRT beam. However (and for obvious reasons), we got an LCD screen in the Gameboy. Well, the new PPU doesn’t alter that part, since LCDs require to be refreshed too. In fact, some special effects achieved thanks to this behaviour will also be supported on the Gameboy.

The Background layer is a 256x256 pixel (32x32 tiles) map containing static tiles. However, remember that only 160x144 is viewable on the screen, so the game decides which part is selected for display. Games can also move the viewable area during gameplay, that’s how the Scrolling Effect is accomplished.

At first, this may sound like a silly feature. After all, the window layer overlaps everything else so what’s it useful for? Well, both Background and Window can be used concurrently at different parts of the screen. This is accomplished by changing the LCDCONT register during specific scan lines.

Sprites are tiles that can move independently around the screen. They can also overlap each other and appear behind the background, the viewable graphic will be decided based on a priority attribute.

To be able to pass these checks, games had to include a copy of Nintendo’s logo (in the form of tiles) in its ROM header Copyright and Trademark laws to control the distribution, Clever huh?. The Gameboy ROM also embeds a copy of the logo to be able to compare it.

Nintendo logo is copied from the cartridge ROM to Display RAM, and then it’s drawn at the top edge of the screen. If there is no cartridge inserted, the logo will contain garbage tiles. The same may happen if it’s badly inserted.

Interestingly enough, the Nintendo logo displayed on the screen is not cleared from VRAM, so games can apply some animation and effects to introduce their own logo.No support for video.20y, a homebrew demo that fiddles with the logo.

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This list is focused on the original Game Boy (GB or DMG, 1989), the Game Boy Color (GBC or CGB) and the Super Game Boy (SGB) are very similar systems, with a few important distinctions, such as:

dmg-schematics - Schematics and annotated overlay for the DMG-CPU B chip, extracted from die photos, made with KiCad. Also contains Electric VLSI library with layouts for some of the cells and memories.

DMG-01 - An educational Gameboy Emulator in Rust and a companion book explaining its development. *Oh Boy! Creating a Game Boy Emulator in Rust- is a talk given at Rust Fest 18 about this.

Infinity - RPG developed by Affinix Software primarily between the years 1999 and 2001. The game never found a publisher and was eventually canceled. Got recently released with the full source, development tools and workflows.

GBVideoPlayer - A technical demo demonstrating how the Game Boy LCD controller can be hacked to make a Game Boy Color play a full motion video in color, together with music.

Thanks to every contributor of this project, Jeff Frohwein, Pascal Felber, KOOPa, Pan of Anthrox, GABY, Marat Fayzullin, Paul Robson, BOWSER, neviksti, Martin "nocash" Korth, Nitro2k01, Duo, Chris Antonellis, Michael Hope, Beware, Jonathan “Lord Nightmare” Gevaryahu, Carsten Sorense, Sindre Aamås, Otaku No Zoku, GeeBee.

The following was typed up for informational purposes regarding the inner workings on the hand-held game machine known as GameBoy, manufactured and designed by Nintendo Co., LTD.

The memory at 0100-014F contains the cartridge header. This area contains information about the program, its entry point, checksums, information about the used MBC chip, the ROM and RAM sizes, etc. Most of the bytes in this area are required to be specified correctly. For more information read the chapter about The Cartridge Header.

The areas from 0000-7FFF and A000-BFFF may be used to connect external hardware. The first area is typically used to address ROM (read only, of course), cartridges with Memory Bank Controllers (MBCs) are additionally using this area to output data (write only) to the MBC chip. The second area is often used to address external RAM, or to address other external hardware (Real Time Clock, etc). External memory is often battery buffered, and may hold saved game positions and high scrore tables (etc.) even when the gameboy is turned of, or when the cartridge is removed. For specific information read the chapter about Memory Bank Controllers.

CAUTION: Stopping LCD operation (Bit 7 from 1 to 0) may be performed during V-Blank ONLY, disabling the display outside of the V-Blank period may damage the hardware. This appears to be a serious issue, Nintendo is reported to reject any games that do not follow this rule.

V-blank can be confirmed when the value of LY is greater than or equal to 144. When the display is disabled the screen is blank (white), and VRAM and OAM can be accessed freely.

Mode 0 is present between 201-207 clks, 2 about 77-83 clks, and 3 about 169-175 clks. A complete cycle through these states takes 456 clks. VBlank lasts 4560 clks. A complete screen refresh occurs every 70224 clks.)

There are various reasons for this interrupt to occur as described by the STAT register ($FF40). One very popular reason is to indicate to the user when the video hardware is about to redraw a given LCD line. This can be useful for dynamically controlling the SCX/SCY registers ($FF43/$FF42) to perform special video effects.

The LY indicates the vertical line to which the present data is transferred to the LCD Driver. The LY can take on any value between 0 through 153. The values between 144 and 153 indicate the V-Blank period. Writing will reset the counter.

The gameboy permanently compares the value of the LYC and LY registers. When both values are identical, the coincident bit in the STAT register becomes set, and (if enabled) a STAT interrupt is requested.

Much like VRAM, Data in Palette Memory cannot be read/written during the time when the LCD Controller is reading from it. (That is when the STAT register indicates Mode 3).

Intensities in range 00h..0Fh are invisible/black (unless eventually under best sunlight circumstances, and when gazing at the screen under obscure viewing angles), unfortunately, these intensities are regulary used by most existing CGB games for medium and darker colors.

Most programs are executing this procedure from inside of their VBlank procedure, but it is possible to execute it during display redraw also, allowing to display more than 40 sprites on the screen (ie. for example 40 sprites in upper half, and other 40 sprites in lower half of the screen).

When using this transfer method, all data is transferred at once. The execution of the program is halted until the transfer has completed. Note that the General Purpose DMA blindly attempts to copy the data, even if the LCD controller is currently accessing VRAM. So General Purpose DMA should be used only if the Display is disabled, or during V-Blank, or (for rather short blocks) during H-Blank.

The gameboy contains two 32x32 tile background maps in VRAM at addresses 9800h-9BFFh and 9C00h-9FFFh. Each can be used either to display “normal” background, or “window” background.

An area of VRAM known as Background Tile Map 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 Data 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 Data Table address for the background can be selected via LCDC register.

When Bit 7 is set, the corresponding BG tile will have priority above all OBJs (regardless of the priority bits in OAM memory). There’s also an Master Priority flag in LCDC register Bit 0 which overrides all other priority bits when cleared.

As one background tile has a size of 8x8 pixels, the BG maps may hold a picture of 256x256 pixels, an area of 160x144 pixels of this picture can be displayed on the LCD screen.

The SCY and SCX registers can be used to scroll the background, allowing to select the origin of the visible 160x144 pixel area within the total 256x256 pixel background map. Background wraps around the screen (i.e. when part of it goes off the screen, it appears on the opposite side.)

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 WX and WY registers. Screen coordinates of the top left corner of a window are WX-7,WY. The tiles for the window are stored in the Tile Data Table. Both the Background and the window share the same Tile Data Table.

GameBoy video controller can display up to 40 sprites either in 8x8 or in 8x16 pixels. Because of a limitation of hardware, only ten sprites can be displayed per scan line. Sprite patterns have the same format as BG tiles, but they are taken from the Sprite Pattern Table located at $8000-8FFF and have unsigned numbering.

Only 10 sprites can be displayed on any one line. When this limit is exceeded, the lower priority sprites (priorities listed above) won’t be displayed. To keep unused sprites from affecting onscreen sprites set their Y coordinate to Y=0 or Y=>144+16. Just setting the X coordinate to X=0 or X=>160+8 on a sprite will hide it but it will still affect other sprites sharing the same lines.

Beside for that, it is also possible to write data directly to the OAM area by using normal LD commands, this works only during the H-Blank and V-Blank periods. The current state of the LCD controller can be read out from the STAT register (FF41).

When the LCD Controller is drawing the screen it is directly reading from Video Memory (VRAM) and from the Sprite Attribute Table (OAM). During these periods the Gameboy CPU may not access the VRAM and OAM. That means, any attempts to write to VRAM/OAM are ignored (the data remains unchanged). And any attempts to read from VRAM/OAM will return undefined data (typically a value of FFh).

When the display is disabled, both VRAM and OAM are accessable at any time. The downside is that the screen is blank (white) during this period, so that disabling the display would be recommended only during initialization.

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 producing sound in four different ways:

The Vin signal is received from the game cartridge bus, allowing external hardware in the cartridge to supply a fifth sound channel, additionally to the gameboys internal four channels. As far as I know this feature isn’t used by any existing games.

The eight gameboy buttons/direction keys are arranged in form of a 2x4 matrix. Select either button or direction keys by writing to this register, then read-out bit 0-3.

The clock signal specifies the rate at which the eight data bits in SB (FF01) are transferred. When the gameboy is communicating with another gameboy (or other computer) then either one must supply internal clock, and the other one must use external clock.

In Non-CGB Mode the gameboy supplies an internal clock of 8192Hz only (allowing to transfer about 1 KByte per second). In CGB Mode four internal clock rates are available, depending on Bit 1 of the SC register, and on whether the CGB Double Speed Mode is used:

The external clock is typically supplied by another gameboy, but might be supplied by another computer (for example if connected to a PCs parallel port), in that case the external clock may have any speed. Even the old/monochrome gameboy is reported to recognizes external clocks of up to 500KHz. And there is no limitiation into the other direction - even when suppling an external clock speed of “1 bit per month”, then the gameboy will still eagerly wait for the next bit(s) to be transferred. It isn’t required that the clock pulses are sent at an regular interval either.

When using external clock then the transfer will not complete until the last bit is received. In case that the second gameboy isn’t supplying a clock signal, if it gets turned off, or if there is no second gameboy connected at all) then transfer will never complete. For this reason the transfer procedure should use a timeout counter, and abort the communication if no response has been received during the timeout interval.

The gameboy that is using internal clock should always execute a small delay between each transfer, in order to ensure that the opponent gameboy has enough time to prepare itself for the next transfer, ie. the gameboy with external clock must have set its transfer start bit before the gameboy with internal clock starts the transfer. Alternately, the two gameboys could switch between internal and external clock for each transferred byte to ensure synchronization.

The serial I/O port on the Gameboy is a very simple setup and is crude compared to standard RS-232 (IBM-PC) or RS-485 (Macintosh) serial ports. There are no start or stop bits.

The above described Timer is the built-in timer in the gameboy. It has nothing to do with the MBC3s battery buffered Real Time Clock - that"s a completely different thing, described in the chapter about Memory Banking Controllers.

When an interrupt signal changes from low to high, then the corresponding bit in the IF register becomes set. For example, Bit 0 becomes set when the LCD controller enters into the V-Blank period.

This chapter describes only CGB (Color Gameboy) registers that didn’t fit into normal categories - most CGB registers are described in the chapter about Video Display (Color Palettes, VRAM Bank, VRAM DMA Transfers, and changed meaning of Bit 0 of LCDC Control register). Also, a changed bit is noted in the chapter about the Serial/Link port.

When using any CGB registers (including those in the Video/Link chapters), you must first unlock CGB features by changing byte 0143h in the cartridge header. Typically use a value of 80h for games which support both CGB and monochrome gameboys, and C0h for games which work on CGBs only. Otherwise, the CGB will operate in monochrome “Non CGB” compatibility mode.

This register is used to prepare the gameboy to switch between CGB Double Speed Mode and Normal Speed Mode. The actual speed switch is performed by executing a STOP command after Bit 0 has been set. After that Bit 0 will be cleared automatically, and the gameboy will operate at the ‘other’ speed. The recommended speed switching procedure in pseudo code would be:

This register allows to input and output data through the CGBs built-in Infrared Port. When reading data, bit 6 and 7 must be set (and obviously Bit 0 must be cleared - if you don’t want to receive your own gameboys IR signal). After sending or receiving data you should reset the register to 00h to reduce battery power consumption again.

Basically, the SGB (Super Gameboy) is an adapter cartridge that allows to play gameboy games on a SNES (Super Nintendo Entertainment System) gaming console. In detail, you plug the gameboy cartridge into the SGB cartridge, then plug the SGB cartridge into the SNES, and then connect the SNES to your TV Set. In result, games can be played and viewed on the TV Set, and are controlled by using the SNES joypad(s).

The SGB cartridge just contains a normal gameboy CPU and normal gameboy video controller. Normally the video signal from this controller would be sent to the LCD screen, however, in this special case the SNES read out the video signal and displays it on the TV set by using a special SNES BIOS ROM which is located in the SGB cartridge. Also, normal gameboy sound output is forwared to the SNES and output to the TV Set, vice versa, joypad input is forwared from the SNES controller(s) to the gameboy joypad inputs.

Any gameboy games which have been designed for normal monochrome handheld gameboys will work with the SGB hardware as well. The SGB will apply a four color palette to these games by replacing the normal four grayshades. The 160x144 pixel gamescreen is displayed in the middle of the 256x224 pixel SNES screen (the unused area is filled by a screen border bitmap). The user may access built-in menues, allowing to change color palette data, to select between several pre-defined borders, etc.

There’s limited ability to colorize the gamescreen by assigning custom color palettes to each 20x18 display characters, however, this works mainly for static display data such like title screens or status bars, the 20x18 color attribute map is non-scrollable, and it is not possible to assign separate colors to moveable foreground sprites (OBJs), so that animated screen regions will be typically restricted to using a single palette of four colors only.

Up to 24 foreground sprites (OBJs) of 8x8 or 16x16 pixels, 16 colors can be displayed. When replacing (or just overlaying) the normal gameboy OBJs by SNES OBJs it’d be thus possible to display OBJs with other colors than normal background area. This method doesn’t appear to be very popular, even though it appears to be quite easy to implement, however, the bottommost character line of the gamescreen will be masked out because this area is used to transfer OAM data to the SNES.

The possibly most popular and most impressive feature is to replace the default SGB screen border by a custom bitmap which is stored in the game cartridge.

Up to four joypads can be conected to the SNES, and SGB software may read-out each of these joypads separately, allowing up to four players to play the same game simultaneously. Unlike for multiplayer handheld games, this requires only one game cartridge and only one SGB/SNES, and no link cables are required, the downside is that all players must share the same display screen.

Beside for normal gameboy sound, a number of digital sound effects is pre-defined in the SNES BIOS, these effects may be accessed quite easily. Programmers whom are familiar with SNES sounds may also access the SNES sound chip, or use the SNES MIDI engine directly in order to produce other sound effects or music.

Because the SGB is synchronized to the SNES CPU, the gameboy system clock is directly chained to the SNES system clock. In result, the gameboy CPU, video controller, timers, and sound frequencies will be all operated approx 2.4% faster as by normal gameboys.

Basically, this should be no problem, and the game will just run a little bit faster. However sensitive musicians may notice that sound frequencies are a bit too high, programs that support SGB functions may avoid this effect by reducing frequencies of gameboy sounds when having detected SGB hardware.

Also, I think that I’ve heard that SNES models which use a 50Hz display refresh rate (rather than 60Hz) are resulting in respectively slower SGB/gameboy timings ???

SGB games are required to have a cartridge header with Nintendo and proper checksum just as normal gameboy games. Also, two special entries must be set in order to unlock SGB functions:

When these entries aren’t set, the game will still work just like all ‘monochrome’ gameboy games, but it cannot access any of the special SGB functions.

The recommended detection method is to send a MLT_REQ command which enables two (or four) joypads. A normal handheld gameboy will ignore this command, a SGB will now return incrementing joypad IDs each time when deselecting keyboard lines (see MLT_REQ description for details).

Now read-out joypad state/IDs several times, and if the ID-numbers are changing, then it is a SGB (a normal gameboy would typically always return 0Fh as ID). Finally, when not intending to use more than one joypad, send another MLT_REQ command in order to re-disable the multi-controller mode.

Because values 01h and FFh are shared for both handhelds and SGBs, it is still required to use the above MLT_REQ detection procedure. As far as I know the SGB2 doesn’t have any extra features which’d require separate SGB2 detection except for curiosity purposes, for example, the game “Tetris DX” chooses to display an alternate SGB border on SGB2s.

Reportedly, some SGB models include link ports (just like handheld gameboy) (my own SGB does not have such an port), possibly this feature is available in SGB2-type models only ???

Command packets (aka Register Files) are transferred from the gameboy to the SNES by using P14 and P15 output lines of the JOYPAD register (FF00h), these lines are normally used to select the two rows in the gameboy keyboard matrix (which still works).

Beside for the packet transfer method, larger data blocks of 4KBytes can be transferred by using the video signal. These transfers are invoked by first sending one of the commands with the ending _TRN (by using normal packet transfer), the 4K data block is then read-out by the SNES from gameboy display memory during the next frame.

even though the SNES receives the data in from display scanlines, it will automatically re-produce the same ordering of bits and bytes, as being originally stored at 8000h-8FFFh in gameboy memory.

The above method works only when recursing the following things: BG Map must display unsigned characters 00h-FFh on the screen; 00h..13h in first line, 14h..27h in next line, etc. The gameboy display must be enabled, the display may not be scrolled, OBJ sprites should not overlap the background tiles, the BGP palette register must be set to E4h.

The display will contain ‘garbage’ during the transfer, this dirt-effect can be avoided by freezing the screen (in the state which has been displayed before the transfer) by using the MASK_EN command.

Of course, this works only when actually executing the game on a SGB (and not on normal handheld gameboys), it’d be thus required to detect the presence of SGB hardware before blindly sending VRAM data.

The SGB/SNES provides 8 palettes of 16 colors each, each color may be defined out of a selection of 34768 colors (15 bit). Palettes 0-3 are used to colorize the gamescreen, only the first four colors of each of these palettes are used. Palettes 4-7 are used for the SGB Border, all 16 colors of each of these palettes may be used.

Effectively, gamescreen palettes can have only three custom colors each, and SGB border palettes only 15 colors each, additionally, color 0 can be used for for all palettes, which will then all share the same color though.

Because the SGB/SNES reads out the gameboy video controllers display signal, it translates the different grayshades from the signal into SNES colors as such:

Note that gameboy colors 0-3 are assigned to user-selectable grayshades by the gameboys BGP, OBP1, and OBP2 registers. There is thus no fixed relationship between gameboy colors 0-3 and SNES colors 0-3.

A direct translation of color 0-3 into color 0-3 may be produced by setting BGP/OBP registers to a value of 0E4h each. However, in case that your program uses black background for example, then you may internally assign background as “White” at the gameboy side by BGP/OBP registers (which is then interpreted as SNES color 0, which is shared for all SNES palettes). The advantage is that you may define Color 0 as Black at the SNES side, and may assign custom colors for Colors 1-3 of each SNES palette.

The length of each line reaches from one end of the screen to the other end. In case that some lines overlap each other, then lines from lastmost data sets will overwrite lines from previous data sets.

Depending on the writing style, data sets are written from left to right, or from top to bottom. In either case the function wraps to the next row/column when reaching the end of the screen.

Used to initialize Attribute Files (ATFs) in SNES RAM. Each ATF consists of 20x18 color attributes for the gameboy screen. This function does not directly affect display attributes. Instead, one of the defined ATFs may be copied to actual display memory at a later time by using ATTR_SET or PAL_SET functions.

Each ATF consists of 90 bytes, that are 5 bytes (20x2bits) for each of the 18 character lines of the gameboy window. The two most significant bits of the first byte define the color attribute (0-3) for the first character of the first line, the next two bits the next character, and so on.

Used to mask the gameboy window, among others this can be used to freeze the gameboy screen before transferring data through VRAM (the SNES then keeps displaying the gameboy screen, even though VRAM doesn’t contain meaningful display information during the transfer).

Used to enable/disable ICON function. Possibly meant to enable/disable SGB/SNES popup menues which might otherwise activated during gameboy game play. By default all functions are enabled (0).

Even though 32x32 map entries are transferred, only upper 32x28 are actually used (256x224 pixels, SNES screen size). The 20x18 entries in the center of the 32x28 area should be set to 0000h as transparent space for the gameboy window to be displayed inside. Reportedly, non-transparent border data will cover the gameboy window.

Instead, when enabled (below execute bit set), data is permanently (each frame) read out from the lower character line of the gameboy screen. To suppress garbage on the display, the lower line is masked, and only the upper 20x17 characters of the gameboy window are used - the masking method is unknwon - frozen, black, or recommended to be covered by the SGB border, or else ??? Also, when the function is enabled, “system attract mode is not performed” - whatever that means ???

The recommended method is to “display” gameboy BG tiles F9h..FFh from left to right as first 7 characters of the bottom-most character line of the gameboy screen. As for normal 4KByte VRAM transfers, this area should not be scrolled, should not be overlapped by gameboy OBJs, and the gameboy BGP palette register should be set up properly. By following that method, SNES OAM data can be defined in the 70h bytes of the gameboy BG tile memory at following addresses:

Basically, the gameboy CPU works more like an older 8080 CPU rather than like a more powerful Z80 CPU. It is, however, supporting CB-prefixed instructions. Also, all known gameboy assemblers using the more obvious Z80-style syntax, rather than the chaotic 8080-style syntax.

The gameboy operates approximately as fast as a 4MHz Z80 (8MHz in CGB double speed mode), execution time of all instructions has been rounded up to a multiple of 4 cycles though.

After displaying the Nintendo Logo, the built-in boot procedure jumps to this address (100h), which should then jump to the actual main program in the cartridge. Usually this 4 byte area contains a NOP instruction, followed by a JP 0150h instruction. But not always.

The gameboys boot procedure verifies the content of this bitmap (after it has displayed it), and locks itself up if these bytes are incorrect. A CGB verifies only the first 18h bytes of the bitmap, but others (for example a pocket gameboy) verify all 30h bytes.

Values with Bit 7 set, and either Bit 2 or 3 set, will switch the gameboy into a special non-CGB-mode with uninitialized palettes. Purpose unknown, eventually this has been supposed to be used to colorize monochrome games that include fixed palette data at a special location in ROM.

Specifies a two character ASCII licensee code, indicating the company or publisher of the game. These two bytes are used in newer games only (games that have been released after the SGB has been invented). Older games are using the header entry at 014B instead.

Specifies the games company/publisher code in range 00-FFh. A value of 33h signalizes that the New License Code in header bytes 0144-0145 is used instead.

Contains a 16 bit checksum (upper byte first) across the whole cartridge ROM. Produced by adding all bytes of the cartridge (except for the two checksum bytes). The Gameboy doesn’t verify this checksum.

As the gameboys 16 bit address bus offers only limited space for ROM and RAM addressing, many games are using Memory Bank Controllers (MBCs) to expand the available address space by bank switching. These MBC chips are located in the game cartridge (ie. not in the gameboy itself), several different MBC types are available:

In each cartridge, the required (or preferred) MBC type should be specified in byte at 0147h of the ROM. (As described in the chapter about The Cartridge Header.)

This is the first MBC chip for the gameboy. Any newer MBC chips are working similiar, so that is relative easy to upgrade a program from one MBC chip to another - or even to make it compatible to several different types of MBCs.

This area is used to address external RAM in the cartridge (if any). External RAM is often battery buffered, allowing to store game positions or high score tables, even if the gameboy is turned off, or if the cartridge is removed from the gameboy. Available RAM sizes are: 2KByte (at A000-A7FF), 8KByte (at A000-BFFF), and 32KByte (in form of four 8K banks at A000-BFFF).

Before external RAM can be read or written, it must be enabled by writing to this address space. It is recommended to disable external RAM after accessing it, in order to protect its contents from damage during power down of the gameboy. Usually the following values are used:

Writing to this address space selects the lower 5 bits of the ROM Bank Number (in range 01-1Fh). When 00h is written, the MBC translates that to bank 01h also. That doesn’t harm so far, because ROM Bank 00h can be always directly accessed by reading from 0000-3FFF.

Beside for the ability to access up to 2MB ROM (128 banks), and 32KB RAM (4 banks), the MBC3 also includes a built-in Real Time Clock (RTC). The RTC requires an external 32.768 kHz Quartz Oscillator, and an external battery (if it should continue to tick when the gameboy is turned off).

Same as for MBC1, except that the whole 7 bits of the RAM Bank Number are written directly to this address. As for the MBC1, writing a value of 00h, will select Bank 01h instead. All other values 01-7Fh select the corresponding ROM Banks.

When writing 00h, and then 01h to this register, the current time becomes latched into the RTC registers. The latched data will not change until it becomes latched again, by repeating the write 00h->01h procedure.

Game Shark and Gamegenie are external cartridge adapters that can be plugged between the gameboy and the actual game cartridge. Hexadecimal codes can be then entered for specific games, typically providing things like Infinite Sex, 255 Cigarettes, or Starting directly in Wonderland Level PRO, etc.

When the GameBoy is powered up, a 256 byte program starting at memory location 0 is executed. This program is located in a ROM inside the GameBoy. The first thing the program does is read the cartridge locations from $104 to $133 and place this graphic of a Nintendo logo on the screen at the top. This image is then scrolled until it is in the middle of the screen.

Two musical notes are then played on the internal speaker. Again, the cartridge locations $104 to $133 are read but this time they are compared with a table in the internal rom. If any byte fails to compare, then the GameBoy stops comparing bytes and simply halts all operations. If all locations compare the same, then the GameBoy starts adding all of the bytes in the cartridge from $134 to $14d.

A value of 25 decimal is added to this total. If the least significant byte of the result is a not a zero, then the GameBoy will stop doing anything. If it is a zero, then the internal ROM is disabled and cartridge program execution begins at location $100 with the following register values:

It is not a good idea to assume the above values will always exist. A later version GameBoy could contain different values than these at reset. Always set these registers on reset rather than assume they are as above.

Cart RAM the first time it is accessed on a real GameBoy contains random data. It will only contain known data if the GameBoy code initializes it to some value.

The STOP instruction is intended to switch the gameboy into VERY low power standby mode. For example, a program may use this feature when it hasn’t sensed keyboard input for a longer period (assuming that somebody forgot to turn off the gameboy).

There’s limited ability to switch between both speeds, for example, a game might use normal speed in the title screen, and double speed in the game, or vice versa.

However, during speed switch the display collapses for a short moment, so that it’d be no good idea to alter speeds within active game or title screen periods.

There is a flaw in the GameBoy hardware that causes trash to be written to OAM RAM if the following commands are used while their 16-bit content is in the range of $FE00 to $FEFF:

NOTE: You should do a bench test before fitting this kit, testing the LCD screen with the protective film on, before installing it into the shell, any issues with the screen kit should be reported to support@zedlabz.com before install.You will need a modified glass screen lens with an enlarged viewing window for this kit (not included), the original size screen lens window is too small, and willobscuresome of the larger LCD panel this upgrade offers.Modified IPS ready or DIY manually cut shell is required to use this kit, centering brackets (not included) but recommended for easier screen alignment.

While most of the games that we cover in this piece are only playable on the more powerful Gameboy Color (The processor is twice as fast as a Game Boy’s, and has three times as much memory), there will be some mentions of some games that were primarily for the original Gameboy.   It was quite a chore going through the Gameboy’s large library (especially when you consider how long the handheld was on the retail market), so I’m sure I missed a few titles. I’m still digging around more, so I just may find some more titles to add to this list. Either way, I’m sure you will find some times below that are quite impressive for this little 8-device.

To the average player, the most apparent limitations are found in the system’s graphics and sound. For graphics, the Game Boy renders sprites and backgrounds in a way very similar to the NES — a grid divides the screen into 8×8-pixel ‘blocks’ forming a total resolution of 160×144 pixels. There are several memory restrictions which determine how graphics are displayed in relation to these blocks, such as the number of sprites that can be on a single line of pixels (10) and the maximum sprite size (8×16). Of course, the Game Boy’s most distinguishing graphical limitation is its green-tinted, 2-bit color palette, which provides a grand total of 4 monochrome shades. We’ll see how developers used this minimalist setup to great effect in just a bit.

The scrolling parallax layers in Chikyuu Kaihou Gun ZAS are a prime example of a Game Boy screen packed to the gills with graphics. Unlike with the Donkey Kong Land series, the limited color palette is implemented smartly, utilizing nearly every available pixel of the screen to build complex textures and sprites without confusing the player or overwhelming the system memory.

Those that have played X often describe it as “Star Fox for the Game Boy”.  Those comparisons are even more understandible once you realize that the chief programmer and designer was Dylan Cuthbert, who worked on Star Fox, the cancelled Star Fox 2, Star Fox Command and Star Fox 64 3D (along with the PixelJunk games).    However, it is worth noting that X ultized vector graphics (similar to Battlezone), while the Star Fox titles used polygon graphics.   Regardless, X was a technical marvel on the DMG-01

But as complex and well-animated as the sprites are, there is also the problem of the limited color palette and screen real estate. Since RARE was dead-set on putting equal detail into both sprites and background elements, the inability to distinguish the two on the Game Boy’s 4-tone LCD is easily the most glaring flaw common to all three DKL titles. HardcoreGaming101 criticizes this decision, calling the results “a blurry, unplayable mess.”

And yet, despite being down-rezzed and re-colored to fit on the Game Boy Color’s screen, Capcom’s remained the most faithful portable version of the original game all the way up until 2009 when it was re-released on iPhone. Considering memory limits, the mere fact that a good majority of this game runs so well off a cartridge is worthy of praise. Dragon’s Lair is indisputably iconic to the storybook adventure genre, and the Game Boy Color has the honor of being among the few portable platforms in history to do it justice.

The gameplay isn’t exactly cutting edge, but the experience is immensely pure and the onscreen result is immediately gratifying and you can’t ignore how good the game looks on the screen. The motions are smooth and the graphics are quite vibrant using the limitations of the GBC.  Dragon’s Lair purists will find faults throughout the game, but you have to give credit where credit is due — the Game Boy Color was never designed for this type of game.

What Makes The Game Special:Strategy games are great on the go, but it’s hard to believe that developers could fit a Warcraft-like RTS experience on the Gameboy Color.    The development team at Bits did an amazing job of having reasonably-sized sprites, have plenty of them on the map (sometimes more than ten on the screen at once), and have it scroll smoothly under most circumstances.   Understandably, the little 8hz processor gets a bit strained and shows some slowdown, but it’s amazing how efficiently Warlocked uses the Game Boy Color’s limited resources.

There were some wonderfully colorful GBC games released in 2000 and 2001, but Warlocked was one of the most skilled in using the limited color palette strategically to create different environments and adapt them to different factors.  For instance, in a snowy level, the entire color palette seems to change to become more winter-like.

Ottifanten: Kommando Störtebeker is another obscure ‘soundtrack’ pick that has a couple of other things going for it as well. The game is based on a popular German cartoon from 2001 and I can only assume that some combination of that and blind luck led them to recruit a composer that clearly knew what they were doing with Game Boy music.

It’s impressive seeing tons of complex sprite graphics and such, but Alone in the Dark totally goes off the deep end when it comes to the kinds of graphics we’re expecting to see on a Game Boy screen. Sure, they’re messy and kind of ugly in some cases. But the Game Boy Color port  of this survival horror classic is pulling some serious stunts to simulate the ambience of its PC and home console counterparts.

The use of color on Alone in the Dark is outstanding and the the backgrounds look like paintings specially colored for the Gameboy Color. The game actually does portray a creepy experience, but personally, I look at this title as more of a technical demo than a good form of entertainment.

All this technical wizardry takes its toll, however. Areas from the original are squashed and shrunk so they’ll fit onto the screen and the cartridge memory, and the entire game takes only around an hour to complete. Still, I have a feeling that if you were to approach most people about doing something like this on Game Boy circa 2001, you’d scare them off, so the effort is certainly commendable.

The Rayman series has always been known for its great character animations, and this version didn’t use the GBC’s 8-bit restrictions as an excuse to break that trend. There’s a lot of graphics packed in here in general, more than the average GBC game. There’s also a CGI animated Rayman that dances before the game’s start screen, just because they could. You might want to turn the sound off though — as nice as some of the graphics are, the soundtrack is painfully underdeveloped and really quite annoying.

A simple puzzle platformer that had the misfortune of releasing around the same time as the Game Boy Advance in 2001, you can tell Toki Tori got some special treatment as a late-to-the-party Game Boy Color release. The main character animations are obviously a cut above the rest, and look CGI quality. Many of the backgrounds also move on separate layers, creating an amazing sense of depth rarely seen on similar GBC platformers. The soundtrack, though repetitive and nauseatingly cheery, also fills out nicely compared to other titles.

While not quite as visual engaging as Shantae, Wendy: Every Witch Way is from the same era and it shows.  This late release is colorful and vibrant with a great cartooney look that makes good use of the Gameboy Color.  However, there is more than visuals that make Wendy worthy of this list.

Unlike most platformers on the Gameboy, Wendy is more than just your standard running and jumping.  Things get much more interesting when you have the ability to reverse gravity on the fly.   Physics aren’t discussed a lot in the Game Boy era, but the gravitational pull effects are actually impressive for the time.  Wendy also has a  There are also three levels that are only available if played on a Game Boy Advance.

Just as it was surprising to see Street Fighter Alpha 2 show up on the Super Nintendo, it was equally surprising to see a port of the original Alpha game on the Gameboy Color. Crawfish Interactive (the team behind the Alpha 3 port for the GBA) produced a surprisingly good port of this great fighter, complete with amazing graphics and excellent control.

The backgrounds of the arcade version are duplicated pretty well, and some even feature animation. This is a very pleasant surprise and adds depth to an otherwise limited Gameboy atmosphere. You’ll find lots of small yet very pleasing surprises all throughout the game. Street Fighter Alpha also featured vertical scrolling — something else that the Neo-Geo Pocket’s fighting games lacked.

Of course, Nintendo brought us Donkey Kong Land on the original Game Boy, but they decided to give the series one more try with a better color palette on the GBC.   Even though, we wouldn’t see a really good port until the Game Boy Advance, who would have thought that Rare and Nintendo would be able to so closely replicate the look and feel of that ground-breaking game on the aging Gameboy Color platform.

Because of memory constraints, the main difference you will notice about the Gameboy version of Donkey Kong Country is that they don’t have both Donkey Kong and Diddy on the screen at once. This will initially throw of many Donkey Kong Country veterans, but its an acceptable trade-off to keep a smooth and enjoyable gameplay experience.

Even though it look better than Donkey Kong Land for the original DMG-01, it didn’t push the GBC hardware quite as hard.  It still has some good animations and some really slimmed down 3D models.  It’s impressive, just not compared to some lesser-known titles.

A lot of effort was taken by Camelot to make Mario Tennis game look good on the Gameboy, and it paid off . The character sprites are very detailed for a Gameboy game and they even manage to squeeze some personality into those tiny pixels. You can easily see all of the features on people’s faces and you can even see the little white lines on the tennis ball move as the ball spins.

With Mario Tennis, you almost have to remind yourself that the Gameboy Color is an 8-bit system Because of the high amount of detail, it can easily be passed up as a 16-bit game at first glance. In fact, having both this game and the recent release of Mario Tennis: Power Tour for the Gameboy Advance (both developed by Camelot), I can tell you that the Gameboy Color version isn’t far behind its 32-bit sibling in terms of animation and how well the system handles the gameplay.

Rare did an excellent job on bringing their SNES powerhouse game, Donkey Kong Country down to the Gameboy. So why not try to bring their headlining N64 shooter to the Gameboy Color as well? Obviously, this time around there needed to be more drastic adjustments in the graphics.

Instead of being a first person shooter, the GBC version of Perfect Dark is built around Konami’s Metal Gear Solid engine for the Gameboy. The most noticeable similarity is the camera perspective, which is from a 45-degree view. (I wonder how it would turn out if they used the Faceball 2000 engine instead)

Even though its not in 3D, the graphics in Perfect Dark are still a highlight, with some of the smoothest animation seen on the Gameboy. Joanna is rendered fairly large walks very naturally. The game is viewed on an angle from above, and the game includes some basic “cut scenes” that add to the story. Perfect Dark probably has the best sound of any original Gameboy game. The digitized speech in the game is gonna blow you away. There must be like 5 minutes of it — pretty good for a Gameboy cart.  I didn’t enjoy the gameplay nearly as much as Metal Gear Solid, but the animation and large sprites definitely pushed the Gameboy Color’s extra power.

You would think that a Gameboy game that is both targeted toward younger girls and uses a licenced Disney theme would suck, but Alice in Wonderland is actually a game that is actually of high quality. Due in part to its Game Boy Color-only status, the screen is overflowing with vibrant colors. They are so good that it’s hard to believe that this game is being played on an 8-bit portable system.

With parallax scrolling and wonderful special effects the game almost reaches Super NES quality. The animation in the game is also very impressive. Alice probably has more frames of animation than some of the characters seen on more powerful home consoles. The locales are ripped right from the cartoon and the characters resemble their on-screen counterparts. The developers did their homework in the graphics department and Disney should be proud to have a game with such fantastic visuals associated with its license.

These three Gameboy Color games are third person adventure games that have a similar style to the LucasArts PC adventure games of old. They were both humorous and enjoyable, but they also utilized the color palette to effectively create enjoyable scenes.

Due to the comical nature of the game, the graphics are animated in a 2D cartoon style which is generally very clean, fresh, and pleasing to the eye. However, due to the limitations of such a small screen, some areas come across as too busy, with the developers obviously trying to cram in as much detail as possible.

The first Wario Land brought new life to the fairly plain Mario Land series on the Gameboy while not only bringing a new gameplay dynamic, but also upping the size of the sprites. Two more Wario Land installments followed, including Wario Land 3 which utilized the Gameboy Colors extra processing power to bring some amazing colors, scenes, and graphical effects.

Each level is very vivid in detail and each enemy is very unique. The trees sometimes have leaves falling from them and other elements such as fire are very well-done. This platformer, Wario Land 3, in addition to Shantae are excellent transition games between the Gameboy Color and Gameboy Advance.

As usual, Nintendo packaged a wonderful combination of graphics and music in this late entry of its landmark series for the Game Boy Color.  If this had been on the original DMG-01, this choice would have been a no-brainer to be a top selection.

Mr. Driller – While Mr. Driller for the Gameboy Color doesn’t use any highly technical graphical effects (what version of Mr. Driller did?), it definitely makes the best use of the Gameboy color’s limited color palette in addition to maxing out the handheld’s memory to keep the animation and gameplay smooth. (eBay)

Street Fighter 2 – While this port of the arcade classic is about as good as you can expect for the original Gameboy, its not nearly as enjoyable as Alpha for the color. Besides the undeniable fact that they’re in black and white, the graphics are really quite good and more arcade-accurate that Alpha’s. However, the game’s choppiness really degrades the game. (eBay)

I just noticed a old gameboy game from 1991 called Mysterium it may look primitive but i am absolutely sure there is not many games like that on gameboy the closest games i can think of like that are X and Faceball 2000 but they arent like Mysterium and generally more advanced !

A full 3D racer on the original Gameboy which actually played better than both the Snes and Megadrive ports. Not the smoothest racer you’ll play but it’s great to see the original GB hardware push some polygons around. Well, more like shuffle them around but still….

I agree, Race Driving should be on here. It’s made by the same people to did X, and it features filled polygons. It’s seriously the greatest achievement for 3D on the original gameboy.