I/O Processor (IOP)

Figure 3.7. Block diagram of the Playstation 2 - I/O Processor

The I/O Processor on the Playstation 2 is actually the Playstation 1 main processor with several extensions to handle USB, Firewire, sound, and the other new peripherals introduced by the Playstation 2. It is a standard MIPS R3000R processor without a MMU and 2MB of local memory. All external I/O such as memory card access, USB control, Firewire devices and sound playback is handled via the IOP. Some of its features include:

Unfortunately, access to the entire IOP is not available to general users due to Sony's need to protect their Intellectual Property from pirates and other nefarious individuals.

USB 1.0 Controller

A relatively gutsy move for Sony at the time was integrating two standard USB ports into the Playstation 2. These are standard USB 1.0 compliant ports and will accept any USB 1.0 compliant device. This includes USB cameras, keyboards, mice, storage devices, speakers, etc.

The USB devices are available to the PS2 Linux kit via the standard Linux USB device filesystem.

Sony i.Link (Firewire) Controller

Another very gutsy move by SCE was to include a i.Link (Firewire) port with the Playstation 2. Sadly, this gamble seems to not have paid off as much as Sony would have liked it to. Only a select few games use the i.Link port. Gran Turismo 3 is probably the most successful PS2 title to use them for networked gameplay.

Unfortunately, the i.Link port is not accessible via the PS2 Linux kit. The IOP controls access via i.Link and the software calls in the closed source SBIOS do not exist for i.Link access.

Sound Processing Unit (SPU2)

The Sound Processing Unit (SPU2) handles all sound mixing and playback. It is a relatively advanced sound processor capable of a variety of sound effects, playback styles and output styles. SPU2 is actually composed of two sound processing cores (CORE0 and CORE1) each with 24-audio channels each. Both SPU cores are identical.

Some SPU2's features include:

  • 48-channels of audio in ADPCM format
  • Software-programmable voices w/ real-time digital effect processing including pitch transformation and modulation, envelope processing and mixing.
  • 2MB of dedicated RAM for sound data
  • 48Khz digital optical output as well as regular analog out