Atari 8-bit Family - Design

Design

The Atari machines consist of a 6502 as the main processor, a combination of ANTIC and GTIA chips to provide graphics, and the POKEY chip to handle sound and serial input/output. These "support" chips are controlled via a series of registers that can be user-controlled via memory set/get instructions running on the 6502. For example, the GTIA uses a series of registers to select colors for the screen; these colors can be changed by inserting the correct values into its registers, which are mapped into "memory" that is visible to the 6502. Some parts of the system also use some of the machine's RAM as a buffer, notably the ANTIC's display buffer and its Display List (essentially a small program written in the chip's simple machine language that tells ANTIChow to interpret that data and turn it into a display), as well as GTIA's Player/Missile (sprite) information. These features enable the computer to perform many functions directly in hardware, such as smooth background scrolling, that would need to be done in software in most other computers of the time.