catalogues and in the less affluent areas". Technical specifications CPU: Atari SALLY (custom variant of the 6502) 1.79 MHz, which drops to 1.19 MHz when the TIA Television Interface Adaptor or RIOT (6532 RAM-I/O-Timer) chips are accessed Unlike a standard 6502, SALLY can be halted in a known state with a single pin to let other devices control the bus. Sometimes referred to by Atari as "6502C", but not the same as the official MOS Technology 6502C. RAM: 4 KB (2 6116 2Kx8 RAM ICs) ROM: built in 4 KB BIOS ROM, 48 KB Cartridge ROM space without bank switching Graphics: MARIA custom chip Resolution: 160×240 (160×288 PAL) or 320×240 (320×288 PAL) Color palette: 256 (16 hues * 16 luma), different graphics modes restricted the number of usable colors and the number of colors per sprite Direct Memory Access (DMA) Graphics clock: 7.15 MHz Line buffer: 200 bytes (double buffering), 160 sprite pixels per scanline, up to 30 sprites per scanline (without background), up to 100 sprites on screen Sprite/zone sizes: 4 to 160 width, height of 4, 8 or 16 pixels Colors per sprite: 1 to 12 (1 to 8 visible colors, 1 to 4 transparency bits) I/O: Joystick and console switch IO handled by 6532 RIOT and TIA Ports 2 joystick ports cartridge port expansion connector power in RF output Sound: TIA as used in the 2600 for video and sound. In 7800 mode it is only used for sound. At least two games include a POKEY sound chip for improved audio. Graphics Graphics are generated by the custom MARIA chip, which uses an approach common in contemporary arcade system boards and is different from other second and third generation consoles. Instead of a limited number of hardware sprites, MARIA treats everything as a sprite described in a series of display lists. Each display list contains pointers to graphics data and color and positioning information. MARIA supports a palette of 256 colors and graphics modes which are either 160 pixels wide or 320 pixels wide. While the 320 pixel modes theoretically enable the 7800 to create games at higher resolution than the 256 pixel wide graphics found in the Nintendo Entertainment System and Master System, the processing demands of MARIA result in most games using the 160 pixel mode. Each sprite can have from 1 to 12 colors, with 3 colors plus transparency being the most common. In