I don't understand how the PLA can be 21 bits wide. The diagram seems to show 8 ... | Hacker News

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		gshubert17 on March 10, 2018 \| parent \| context \| favorite \| on: How MOS 6502 Illegal Opcodes Work (2008) I don't understand how the PLA can be 21 bits wide. The diagram seems to show 8 ON bits, 8 OFF bits, and 6 timing bits, which adds up to 22 bits. Any clarification?

monocasa on March 11, 2018 [–]

It's a simplified explanation.

http://visual6502.org/wiki/index.php?title=6507_Decode_ROM

> Note that the lower two bits are always XX - the decode ROM doesn't actually check these, but check a cooked version of these bits instead.

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