![68B21 PIA / 6821 (MC68B21P) 68B21 PIA / 6821 (MC68B21P)](https://www.pinball.center/6787-large_default/68b21-pia--6821-mc68b21p.jpg)
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68B21 Peripheral Interface Adapter.
This is the faster B version that can be used as a 6821 or 68B21 and is a better chip overall. It was used on lots of 80's pinballs and video games.