Nintendo Game boy gameconsole

Nintendo Game boy I've owned almost every version of the Nintendo Game Boy and my kids have played on it. The Game Boy is a small portable game console developed by the Japanese company Nintendo. The first design was quite simple and over the years there have been again improved versions developed by Nintendo. The original Nintendo Game Boy was released in 1990 in the Benelux. The first version was based on a variant of the Z80 microprocessor with a small black and white LCD display without backlight. The spiritual father of the Game boy was Gunpei Yokoi who initially conceived the game console Game & Watch which was a great success. An important drawback was that there only one game was on. The solution to this was the Game Boy with its interchangeable cartridges. Despite a fairly low resolution black and white screen and a one channel beeping sound, the games were fantastic for the time and the Game boy was a commercial success.

Nintendo Game boy pocket The first successor was the Game Boy Pocket which came out in 1996, the big difference with the first Game Boy is that the Game Boy Pocket is smaller and lighter and that it only needed two batteries instead of four with the original Game Boy. For the rest it was still complete compatible with the first Gameboy.

Nintendo Game boy color Then the Game boy color came out in 1998, even with this new version all old game cartridges could still be played on the Game Boy Color. In addition to the color screen, there were a few other nice expansions, it became possible to compete against each other with Game Boy play via a cable or wirelessly via infrared, in the later Game Boys the option to play via infrared has been deleted again. Also there was a headphone jack, as with the Game Boy Advance. The CPU was still the 8 bit-Sharp LR35902 (Z80-compatible processor) with a clock speed of 4 MHz or 8 MHz, the ram memory was 32 kB but memory could banking also have 128 kB on the game cartridge. The maximum rom size was still 8 MB, but there were now two sound channels (stereo) and the display was a 160×144 pixel TFT LCD made by Sharp with 32,768 colors of which 56 colors were displayed simultaneously on the screen. As with the Game boy pocket, this Game boy color ran on 2 AA batteries that lasted for about 13 hours of playtime. An AC adapter (DC 3 V) was also available.

Nintendo Game boy advance After this, the Game Boy Advance (abbreviated as GBA) came out in 2001. The Game Boy Advance was therefore the successor of the Game Boy Color and it was the first Game boy with a 32-bit processor (16 Mhz ARM7TDMI-RISC-CPU). It also had an 8 bit Z80 coprocessor at 4 or 8 MHz to still be able to run the old games. The memory was a respectable 32 kilobytes + 96 kilobytes of VRAM (internal to the processor) and the capability for 256 kilobytes of DRAM externally. The display was a 74mm LCD screen with 32,768 colors and a resolution of 240 x 160 pixels. The device also ran on 2 AA batteries for about 15 hours of playing time, and here too an AC adapter was available. You can also play without batteries using an adapter.

Nintendo Game boy advance SP After this, the Game Boy Advance SP came on the market in 2003, SP stood for Special Project. The Game Boy Advance SP was an improved version of the original Game Boy Advance from 2001. Notable improvements included the built-in backlight, a rechargeable lithium-ion battery, and a new folding design. The Game Boy Advance SP was much smaller when folded and the screen was well protected when folded. The charging time was 3 hours and on the special adapter only original AC adapters could be used. This Game boy also had a 32-bit processor (16 Mhz ARM7TDMI-RISC-CPU) and a 8 bit Z80 coprocessor at 4 or 8 MHz to still be able to play the old games. Various colors were available.

Nintendo Game boy micro The only version I haven't owned myself is the Game Boy Micro that first released in late 2005. Unlike the Game Boy Advance and SP, the Game Boy Micro could only play Game Boy Advance games, the Game Boy color and the original Game Boy games could no longer be played, which was the breaking of an old Nintendo tradition. This was also the last Game Boy console that Nintendo released. The Game Boy Advance was already succeeded in 2004 by a new type of portable console, the Nintendo DS.

Defferent cartidges

Games were released on game cartridges officially called "Game Pak" by Nintendo. The first cartridges had a size measuring 5.8 by 6.5 cm, later smaller cartridges appeared that were half as high. A cartridge contains a ROM memory where the code of game, there are also cartridges that also contain a small battery with SRAM, flash memory chip or EEPROM with which game data could be saved. When the battery was exhausted, the stored data was also lost, but it is possible to to replace the battery. To do this, you have to open the cartridge and solder it. Listed below are the first cartridges that are gray, the second generation that was black and after that the cartridges became half as high on some Game boy advance games. There is also a cut-away cartridge where the battery is clearly visible.

Grey Gameboy cartridge
Black Gameboy cartridge
Gameboy cartridge advance
Gameboy cartridge inside

In terms of hardware, there are also several types of Game boy cartridges, two of them are the MBC1 and MBC2 types, of which here you can find the electronics schematics with the most important differences.

Gameboy cartridge type 1
Gameboy cartridge type 2

The Memory bank controllers (MBCs) ensured that the memory banks were shifted in the right place (the 8 bit CPU could only see 8 KB of ROM at a time) and also controlled the RAM in the cartridge. The MBCs had a register for this (5 bits on the MBC1, 4 bits on the MBC2) where the memory bank could be selected. MBC1 is controlled by A15..A13 and MBC2 by A15,A14,A8. The bank is in D0..D4 (D0..D3 for MBC2). When both RAM and ROM was present, A15 (low is ROM) controlled the selection.

Specifications original Game boy

  • CPU: 8 bit-Sharp LR35902 (Z80-compatible processor) 4.194304MHz
  • RAM: 8kB internal
  • VRAM: 8kB internal
  • ROM: 256 kBit, 512 kBit, 1 MBit, 2 MBit and 4 MBit cartridges by mens of memory banking
  • Display: LCD 160 x 144 dots, 4 shades of gray.
  • Power: 6 Volts, 0.7 Watts - 4 AA Batteries

In my archive I found another PDF with the complete technical description of the Nintendo Game boy, everything about the special processor with missing and additional instruction set, the memory map, the sound and the video hardware, everything you ever wanted to know about the technique of the Nintendo Game Boy is in this deocument.

Download the PDF file!


The security protections of the Nintendo Gameboy

Eerste Gameboy One of the most iconic handheld game consoles is the Nintendo Gameboy. When Nintendo released the Gameboy, they also thought carefully about copying protections of both the cartridges and the Gameboy hardware. For this they used some tricks that made it almost impossible for a long time to clone the Gameboy. Today there are a large number of emulators that mimic the behavior of the entire Gamboy in software. Most Gameboy clones (especially the Chinese clones) all contain a 16 or 32 bit processor that can run the complete Gameboy (and often other game consoles) perfectly. But when the Gameboy came on the market, this was not an option at all, so they chose to make it very difficult to "reverse engineer" the Gameboy. Nowadays the “reverse engineering” tools and methods have become so advanced that the Gameboy has also had to give up its secrets.

Nintendo was the first to make its own SOC (System On Chip) for the Nintendo Gameboy. This chip was made by the firm Sharp and was referred to by the name DMG CPU or Sharp LR35902. The processor part on this chip is a mix between the Z80 and the Intel 8080. It didn't have the IY and IY (index) registers of the Z80, the register set is the same as the 8080. Also there are no IN and OUT instructions so there is no I/O space, all controls were memory mapped. In addition, have they added a few extra instructions that weren't in the 8080 and Z80. There was also 8 KB of Ram on the chip. In addition, there was also a PPU for control of the on-chip LCD display and a simple four-channel Audio Processing Unit. Since this was all baked in one chip, without any kind of documentation (except probably for developers who signed a Non disclosure agreement), it was virtually impossible for a third party to Game Boy imitation. But that wasn't all.

The CPU (or SOC) chip also contained 256 bytes of ROM code containing the bootstrap code. This code first performs a number of checks on the cartridge to see whether it is there correctly, but also meets a number of characteristics and a special checksum (control number) before the game will be started. One of the things to be checked was the Nintendo logo. This was also copied to the LCD and this was the familiar scrolling up logo on the screen at the Startup. When there was no cartridge in it, the code only read 0xFF (all bits on) which showed a black block on the LCD screen.

Then a checksum was made of the cartridge ROM and when it was not correct the Nintendo Gameboy froze and nothing was executed. Since this code was baked into the silicon, it could not be read in any way and was therefore a Nintendo secret. A few years ago fanatics have looked at silicon with a heavy microscope and discovered the code location and decoded the zeros and ones.

The 256 bytes ROM was able to disable itself, this was done by the last instruction in this ROM called "lock out". This was also a security so that a cartridge could not read the internal ROM. Very cleverly done by Nintendo. A less smart move was that they only tested the first bytes of the Nintendo logo so there were jokers who changed the logo in a funny way.

Although there are currently many (Chinese) Gameboy / NES clones and a large number of emulators in software and even in FPGA chips, Nintendo certainly has successfully prevented copying/cloning of their products for the first few decades. They also have some of these protections in later products that are still applied. Various listings of the code of the Gameboy bootrom can be found on the Internet.


Last update: 11-05-2022


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