ps1: cache isolate bit should isolate i-cache, not d-cache (scratchpad)

[LukeUsher]

One obvious improvement is that this solves the 'black road' issue in Ridge Racer (note that the broken polygons are part of an unrelated problem)

As this is such a fundamental flaw, chances are there are significant improvements to other games too.

before:

after:

[PatrickvL]

...and how does this title look in PolyBlast? ;)

[ghost]

This is a definite improvement, but my understanding is cache isolate can isolate both caches (or both tag line caches with the caveat that there are no data cache tags) based on the settings of $fffe:0130. I don't know the exact combinations that enable what, but there's bits for tag testing and code/data/stratchpad enable, among many other settings.

[LukeUsher]

This is a definite improvement, but my understanding is cache isolate can isolate both caches (or both tag line caches with the caveat that there are no data cache tags) based on the settings of $fffe:0130. I don't know the exact combinations that enable what, but there's bits for tag testing and code/data/stratchpad enable, among many other settings.

Has this behaviour been hardware tested at all? We know the data cache and other cache-related portions are different on the ps1 cpu than other chips of the same family.

[Screwtapello]

Thanks for figuring this out!