The A9X chip with 64-bit architecture used in the iPad Pro 12.9-inch 1st generation is a powerful processor designed by Apple. It features a dual-core CPU and a 12-core GPU, making it capable of handling demanding tasks such as video editing, graphic design, and gaming. The A9X chip also includes an M9 motion coprocessor, which allows the device to track motion and activity data with high accuracy. This chip is optimized for iOS and iPadOS, providing smooth and responsive performance that enables users to run multiple apps simultaneously and switch between them with ease. Additionally, the A9X chip provides up to 10 hours of battery life, ensuring that users can use the device for extended periods without needing to recharge. Overall, the A9X chip with 64-bit architecture is a key feature that contributes to the high-performance capabilities of the iPad Pro 12.9-inch 1st generation.