Comment by brucehoult

Also a user-programmable 300 MHz 8051 (8 bit) primarily there to manage timers and interrupts and wake up the big 64 bit cores.

Note that the application-processor 1 GHz C906 and Arm A53 are either/or, you can't run both at the same time — similar to the Arm M33 and RISC-V Hazard3 core pairs on the Raspberry Pi RP2350.