The BCM7358 is based on a MIPS32 architecture. It is an entry-level high-definition (HD) satellite System-on-a-Chip (SoC) designed specifically for single-tuner set-top boxes.
Core Architectural Features:

    CPU: It features a high-performance MIPS32 24K-class processor core. This core typically operates at speeds around 500 MHz (though specific clock speeds may vary depending on the implementation).
    Integration: As a single-chip solution, it integrates the following:
        Full HD (1080p) video decoding support.
        Advanced security engine for digital rights management (DRM) and conditional access (CA).
        Integrated LNA (Low Noise Amplifier), tuners, and demodulators.
        Support for multiple memory interfaces, typically including DDR3 to minimize system cost.
    Efficiency: The architecture is optimized for low power consumption, allowing for small-form-factor set-top box designs that do not require active cooling (fans).

Detailed architectural diagrams, pinouts, and register-level documentation are proprietary and are only available to authorized Broadcom customers through the Broadcom docSAFE portal. Access requires a Broadcom support account and an active maintenance contract or NDA.


Source: Broadcom chat bot