The Nintendo Game Boy Advance is powered by two AA batteries and accepts rechargeable batteries, rechargeable battery packs, and AC power through an adapter. The system operates for up to eight hours of continuous usage on a single charge. It has a 16.78 MHz ARM7TDMI CPU for its central processor and an 8 or 4 MHz Z80 coprocessor for backward compatibility. The Z80 processor automatically activates and switches to the correct MHz rating when it detects the presence of Game Boy Color or original Game Boy games upon booting of the machine. The ARM7TDMI CPU is optimized for sprites and displays up to 50 of them on the screen at a time. It has a 240x160 (HQVGA) pixel resolution with Custom 2D core 32-bit graphics, although it is also capable of displaying basic "Mode 7" style 3D in some games. Pixels are sharp and crisp and represent a full RGB color palette. The LCD screen is lit by ambient light, increasing the longevity of the batteries. The "landscape" form factor is designed for long-term comfort, with the D-pad, buttons, and shoulder buttons located for optimal ergonomics. The Advance is capable of playing thousands of games on cartridge. Due to its popularity and longevity, a large number of accessories and add-ons were introduced. The e-reader attachment enables play of classic Nintendo software on the system via data cards, and some cartoons are available via special video cartridges. Third party support is also strong, with front lighting kits and external lights being widely available. Due to the system's power, a large number of games from the NES and SNES library were also ported to the system. The graphical power of the system is equivalent to the SNES, although its 32-bit nature allows the display of more and more vibrant colors, as demonstrated on many original pieces of software developed for the system. Due to the powerful processor, it is capable of displaying full motion video at 30 frames per second, and most software runs at the same rate.