SEGA SATURN DEVELOPER'S MANUAL

■ Function

The SCU functions are shown below.

Data transfer between main CPU, internal DSP, A-bus, and B-bus: SCU is equipped with CPU I / F, A-bus I / F, and B-bus I / F, and interfaces with multiple processors connected to each I / F via the bus Run smoothly. In addition, programs can be transferred from the main CPU to the DSP inside the SCU. In addition, during data transfer between A-bus and B-bus, processing can be performed using independent buses in parallel, such as the work area can be accessed from the CPU using the CPU-bus. The
Interrupt control: Interrupts that span other processors are issued via the SCU. For example, when you want to display the volume level on the screen, the SCSP generates a screen display request interrupt to the SCU. In addition, the SCU recognizes the interrupt and issues the interrupt while synchronizing with the screen. At this time, an interrupt can be issued at any point (dot) on the screen.
Internal DSP: SCU has a built-in DSP. This is provided to achieve processing that is too difficult to achieve with the main CPU alone.
Operating frequency: The DSP operating frequency inside the SCU operates at half the frequency of the main CPU. For the operating frequency of the main CPU, refer to the main CPU manual.