Memory map: Difference between revisions
Jump to navigation
Jump to search
Content added Content deleted
No edit summary |
No edit summary |
||
| Line 99: | Line 99: | ||
* Writes: RCP will ignore the requested access size and just write the word that was put on the bus directly into the hardware register. For 8-bit and 16-bit accesses, this means that the shifted value prepared by the VR4300 is the one that will be written verbatim. Reprising the example above, if <code>S0=0x1234'5678</code>, <code>A0=0x0460'0011</code>, running <code>SB S0, 0(A0)</code> will write the value <code>0x5678'0000</code> to the RCP hardware register <code>0x0460'0010</code>. For 64-bit accesses, as they are written on the bus MSB-first, the RCP will write the MSB to the hardware register, ignoring the LSB. |
* Writes: RCP will ignore the requested access size and just write the word that was put on the bus directly into the hardware register. For 8-bit and 16-bit accesses, this means that the shifted value prepared by the VR4300 is the one that will be written verbatim. Reprising the example above, if <code>S0=0x1234'5678</code>, <code>A0=0x0460'0011</code>, running <code>SB S0, 0(A0)</code> will write the value <code>0x5678'0000</code> to the RCP hardware register <code>0x0460'0010</code>. For 64-bit accesses, as they are written on the bus MSB-first, the RCP will write the MSB to the hardware register, ignoring the LSB. |
||
=== |
=== Range 0x1FC0'0000 - 0x1FCF'FFFF (PIF access via SI) === |
||
TODO |
|||
=== All other ranges 0x0500'0000 - 0xFFFF'FFFF (External SysAD bus via PI) === |
|||
All accesses made by the VR4300 in these ranges are forward externally by RCP on the external bus via PI. This allows the CPU to access external devices like the cartridge ROM and SRAM. |
All accesses made by the VR4300 in these ranges are forward externally by RCP on the external bus via PI. This allows the CPU to access external devices like the cartridge ROM and SRAM. |
||