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Recursive Acronym
Joined: 01 Jan 2008
Posts: 5
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 Posted: Wed Jan 09, 2008 2:03 am Post subject: Is the CPU 32 bit or 64 bit? |
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| Wikipedia says that the PSP has a "32-bit MIPS32 R4k-based CPU", although it is elsewhere documented that the R4k (R4000) is a 64-bit CPU. Which is it? |
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crazyc
Joined: 17 Jun 2005
Posts: 410
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| Posted: Wed Jan 09, 2008 2:19 am Post subject: Re: Is the CPU 32 bit or 64 bit? |
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| Recursive Acronym wrote: | | Wikipedia says that the PSP has a "32-bit MIPS32 R4k-based CPU", although it is elsewhere documented that the R4k (R4000) is a 64-bit CPU. Which is it? |
It's not a R4000 (they probably meant MIPS32-4k and everyone misunderstood). It implements a slightly modified MIPS32R2 ISA. |
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hlide
Joined: 10 Sep 2006
Posts: 750
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| Posted: Wed Jan 09, 2008 6:08 am Post subject: |
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| it is mostly a modified version named Allegrex based on R4100 with no 64-bit support at all. if i'm not wrong, all MIPS32R2 SPECIAL2 instructions are mapped to the SPECIAL instructions space instead of the usual SPECIAL2 instructions space for instance, which is why using a vanilla MIPS gcc generating those SPECIAL2 instructions might be incompatible with Allegrex (not something i checked). |
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