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The Xbox gpu and apu are 'off-the-shelf' in the sense that they were re-used in nvidia retail chips. But you're right, that doesn't mean much in terms of public

by espes 11y ago

The Xbox gpu and apu are 'off-the-shelf' in the sense that they were re-used in nvidia retail chips. But you're right, that doesn't mean much in terms of public documentation. So you do some reverse-engineering. On the whole it isn't much work than other consoles of that generation. The only reason there hasn't been any activity is because nobody (outside of the Xbox backwards compatibility team) sat down and did the work (because there's no incentive to)

pandaman 11y ago
>The Xbox gpu and apu are 'off-the-shelf' in the sense that they were re-used in nvidia retail chips. Not really[1]. It was based on the GeFroce 3 architecture (NV20) but the actual chip had been quite different from the ones you could get on a retail card (NV2A). Even if it had been a straight off-the-shelf device it does not mean you know how it works. Look at the open-source drivers for the off-the-shelf video cards to see what is possible through reverse-engineering and what is not. I cannot speak for other consoles of that generation, as I have not touched the GC but PS2 devkits came with nice printed manuals, describing every register and every command for almost every device (if memory serves there was not printed IOP manual but it was pretty much the PS1 chipset so its documentation had been obtainable too). 1. https://en.wikipedia.org/wiki/GeForce_3_series https://en.wikipedia.org/wiki/GeForce_3_series
- espes 11y ago
  The actual graphics core has only elementary differences from the retail chips [1]. The differences were mainly in integration (merging in a northbridge, tweaks for UMA, ...) 1. https://github.com/espes/xqemu/blob/xbox/hw/xbox/nv2a.c#L708 https://github.com/espes/xqemu/blob/xbox/hw/xbox/nv2a.c#L708
- dogma1138 11y ago
  You can get very detailed ISA's for GPU's NVIDIA ones require an NDA (rubber stamped to some degree). There have been quite a few Xbox 360 and Xbox SDK's appearing on Ebay, even some of the early PowerPC based Mac Soft SDK's for the Xbox 360 have appeared online so some one has them, too bad that people who buy them either collect them or in the case of the 360 dev box to create free XBLA gold accounts :P

by espes 11y ago

pandaman 11y ago

>The Xbox gpu and apu are 'off-the-shelf' in the sense that they were re-used in nvidia retail chips. Not really[1]. It was based on the GeFroce 3 architecture (NV20) but the actual chip had been quite different from the ones you could get on a retail card (NV2A). Even if it had been a straight off-the-shelf device it does not mean you know how it works. Look at the open-source drivers for the off-the-shelf video cards to see what is possible through reverse-engineering and what is not. I cannot speak for other consoles of that generation, as I have not touched the GC but PS2 devkits came with nice printed manuals, describing every register and every command for almost every device (if memory serves there was not printed IOP manual but it was pretty much the PS1 chipset so its documentation had been obtainable too). 1. https://en.wikipedia.org/wiki/GeForce_3_series https://en.wikipedia.org/wiki/GeForce_3_series

espes 11y ago
The actual graphics core has only elementary differences from the retail chips [1]. The differences were mainly in integration (merging in a northbridge, tweaks for UMA, ...) 1. https://github.com/espes/xqemu/blob/xbox/hw/xbox/nv2a.c#L708 https://github.com/espes/xqemu/blob/xbox/hw/xbox/nv2a.c#L708
dogma1138 11y ago
You can get very detailed ISA's for GPU's NVIDIA ones require an NDA (rubber stamped to some degree). There have been quite a few Xbox 360 and Xbox SDK's appearing on Ebay, even some of the early PowerPC based Mac Soft SDK's for the Xbox 360 have appeared online so some one has them, too bad that people who buy them either collect them or in the case of the 360 dev box to create free XBLA gold accounts :P