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psx:gpu [2012/10/23 13:00]
amidog created
psx:gpu [2013/08/25 21:38] (current)
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 +====== GPU Version ======
 +There are atleast two different GPU versions, the old v0 one used in early SCPH-100x models, and the new v2 one used in later models. Here are the differences and/or issues I have observed.
 +^ ^Old ^New ^Note ^
 +|Status after reset|<​code>​0x14800000</​code>​|<​code>​0x14802000</​code>​|-|
 +|Modulate|<​code>​((color & 0xf8) * (texel << 3)) >> 7</​code>​|<​code>​(color * (texel << 3)) >> 7</​code>​|In old GPU, the least significant bits are ignored.|
 +|Drawing area|9-bit (max 511) vertically|10-bit (max 1023) vertically|The new GPU seems to support 2MB VRAM.|
 +|GPU info|8 possible results, version = 0|16 possible results, version = 2|-|
 +|Framebuffer rectangle (0x02)|There is an "​interesting"​ bug when <​code>​(x_pos & 15) == 15</​code>​|-|Bug has been fixed in new GPU.|
 +|VRAM move (0x80)|-|Large moves will make the GPU freeze|I haven'​t observed any VRAM move freezes on the old GPU while I can repeatedly freeze the new GPU by issuing one or two large VRAM moves.|
 +|Sprite X/Y-flip (mirror)|N/​A|Supported|-|
 ====== Resolution ====== ====== Resolution ======