6.6 Input / Output

The Nintendo 64 system spends a good deal of its time performing I/O operations. The operating system provides an optimized I/O interface layer that directly communicates with the hardware. Some of these interfaces include:

VI (the video interface)

The interface routines communicate with a video manager system thread, called the VI/Timer manager. This thread receives all vertical retrace interrupts and programs the video hardware. In addition, it also receives all counter interrupt messages and executes timer functions.

PI (the peripheral interface)

The PI also has an associated I/O manager thread, the PI manager. It controls access to the ROM cartridge so that two threads do not attempt to DMA from ROM to RAM at the same time.

AI (the audio interface)

This interface programs the audio hardware to output the desired sample rate and manages access to the audio data buffer.

DP (the RDP interface)

The interface is of importance mostly because it has an associated system event when a DP operation is complete.

Cont (the controller interface)

This interface resets, detects, obtains status, queries and reads data from the game controllers.