Finding official firmware is the hardest part. Allwinner does not distribute to end-users directly. Try these sources:
Firmware is the software that controls the hardware components of a device, acting as a bridge between the operating system and the hardware. It manages the device's functionality, configures the hardware, and provides a platform for running applications. Firmware can be thought of as the device's personality, influencing its behavior, and performance. Allwinner A133 Firmware