Reset IOP

[cyx]

anyone care to explain what is "reset IOP" for ? and case where it should on/off.

[dlanor]

anyone care to explain what is "reset IOP" for ? and case where it should on/off.

OK, here're the basics about it.

The PS2 has two main processors that work in parallel. The 'chief' is known as the EE (idiotic Sony abbreviation for "Emotion Engine", believe it or not... ), which runs the main code of most programs, be they games or LaunchELF etc.

The secondary processor is known as IOP, a somewhat better abbreviation of "Input Output Processor". Each of these processors has separate RAM, or as we often say, they live in separate spaces, EE space and IOP space. They can 'peek' into the other space, and even 'poke' a little, but the main communication between them is through an RPC protocol (Remote Procedure Call), and a series of Sifxxx functions. (System InterFace)

When a program in EE space needs to access hardware of various kinds, it needs device drivers for that, So it uses some of the function calls mentioned above to load IRX drivers into IOP space, and then the RPC functions can be used to access functions of those drivers, almost as if they were running on the same processor as the calling program.

However, when one EE program is launched by another such program, it is possible that the needs of the new program conflicts with those of the old one, so that it becomes necessary to throw out the IRXs already loaded, and make a fresh start. That is the purpose of IOP reset.

For most cases where you use LaunchELF, you should have IOP reset active, as it eliminates the risk of using incompatible drivers, possibly left in IOP RAM by whatever program launched LaunchELF. But in some cases you need to disable IOP reset, precisely because you want to keep old IRXs active. One typical example of that would be when you use PS2Link to run LaunchELF, and want to retain the ability to reset PS2Link by network commands sent from the PC.

Best regards: dlanor