6502 is the heart of the computer. It's based on MOS Technologies 6502. While the 400/800 models contain a generic 6502 CPU, all of the XL/XE models contain Atari's customized 6502C chip. 6502c has an extra line called HALT. It is controlled by ANTIC which it uses whenever it needs the / bus. The HALT line must be pulled high for the chip to work. Early 400/800 NTSC computers used a standard 6502 and 4 additional chips to stop the processor when ANTIC needed the busses.

Catalogue numbers

CO14377 (6502B - used in 400/800 models - standard 6502)
CO14806 (6502C - used in XL/XE models - customized)


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