Editing Atari 600XL (section)

== Architecture and Processor ==
The 600XL is powered by the '''MOS Technology 6502C''' microprocessor (designated "SALLY" by Atari, part number C014806), running at:
* '''1.79 MHz''' (NTSC systems)
* '''1.77 MHz''' (PAL systems)

The SALLY variant of the 6502 includes a HALT line that allows the ANTIC chip to pause the CPU during screen rendering for direct memory access (DMA), a feature unique to Atari's implementation.

The CPU is supported by Atari's custom chipset:
* '''ANTIC''' (C012296) – Alphanumeric Television Interface Controller. A programmable co-processor that generates display lists and handles graphics modes independently of the CPU.
* '''GTIA''' (C014805) – Graphics Television Interface Adapter. Manages colour output, player/missile graphics (sprites), and collision detection. An evolution of the earlier CTIA chip.
* '''POKEY''' (C012294) – Pot Keyboard Integrated Circuit. Provides four-channel audio, keyboard scanning, serial I/O (SIO) control, paddle input, and random number generation.
* '''PIA''' (6520) – Peripheral Interface Adapter. Handles parallel I/O for joystick ports and peripheral control lines.

This architecture is identical to the 800XL, giving the 600XL the same graphics, sound, and I/O capabilities despite its lower price point.