RDP The Graphics Processor

Command Interface

TODO: Complete documentation on the DPC registers

The RDP status register defines bits 9 and 10 as start valid and end value.

I believe 0 represents valid, and 1 represents invalid according the way the graphics ucode uses the start valid bit.

It seems that the RDP would turn on these bits when it starts reading a display list into the internal command buffer, when it finishes, they get cleared. The graphics ucode running on the RSP waits till the RDP is done reading a display list so it can start building the next display list for the RDP. No one seems to check the end valid bit maybe due to predictability.

There is a command busy flag, which is an indication flag that the RDP is currently executing a RDP command.