A logic option that allows the Compiler to create carry chains automatically by inserting CARRY_SUM buffers into the design. This option is also required to recognize carry chains in any design containing MAX+PLUS^® II-style CARRY buffers. The length of the chains is controlled with the Carry Chain Length option. If this option is turned off, CARRY buffers are ignored, but CARRY_SUM buffers are unaffected.

This option is ignored if it is assigned to anything other than a design entity. The Auto Carry Chains option is also ignored if you select Product Term or ROM as the setting for the Technology Mapper option. This option is available for All Altera^® devices supported by the Quartus^® II software except MAX^® 3000, MAX 7000AE, and MAX 7000B devices.

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