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On this page you can find a description of some of the registers available in the "Broadway" CPU. The "Broadway" CPU is an enhanced version of the "Gekko" CPU developed for the Nintendo GameCube videoconsole, which is based on the PowerPC 750CXe CPU design.

Special Purpose Registers (SPRs)

Most of these registers are already present on 750CX or Gekko. Others seem to be new (like HID4).

Name Number Description
GQR0 912 (0x390) Graphics Quantization Register 0
GQR1 913 (0x391) Graphics Quantization Register 1
GQR2 914 (0x392) Graphics Quantization Register 2
GQR3 915 (0x393) Graphics Quantization Register 3
GQR4 916 (0x394) Graphics Quantization Register 4
GQR5 917 (0x395) Graphics Quantization Register 5
GQR6 918 (0x396) Graphics Quantization Register 6
GQR7 919 (0x397) Graphics Quantization Register 7
HID0 1008 (0x3F0) Hardware Implementation-Dependent register 0
HID1 1009 (0x3F1) Hardware Implementation-Dependent register 1
HID2 920 (0x398) Hardware Implementation-Dependent register 2
HID4 1011 (0x3F3) Hardware Implementation-Dependent register 4
L2CR 1017 (0x3F9) Layer 2 cache Control Register
MMCR0 952 (0x3B8) Monitor Mode Control Register 0
MMCR1 956 (0x3BC) Monitor Mode Control Register 1
PMC1 953 (0x3B9) Performance Monitor Counter register 1
PMC2 954 (0x3BA) Performance Monitor Counter register 2
PMC3 957 (0x3BD) Performance Monitor Counter register 3
PMC4 958 (0x3BE) Performance Monitor Counter register 4
WPAR 921 (0x399) Write-gather Pipe Address Register
... ... ...


Bit 28 (0x8) seems to be related to instruction syncs; PPCSync enables this, runs sync, and restores the old value.


Bit 30 (second most significant) determines whether paired singles should be stored by Revolution OS on context switch.


Bit 31 (most significant bit) is H4A (unknown purpose). The "Broadway" CPU seems to have a bug which makes unreliable to clear this bit, as noted in some strings in the SDK.