The Broadway is the Wii's main CPU. It is a 32-bit PowerPC CPU based on the PowerPC 750CL. It is based on the GameCube Gekko CPU design, being almost identical other than an overclock and the addition of a few new features.
New features from Gekko
(following text copied from official document "Summary of changes to Gekko User's Manual to turn it into a Broadway User's Manual")
The major changes from Gekko to Broadway, covered in the UM are:
- 1) L2 cache configurable for 32-B fetch mode, 64B-fetch mode or 128B-fetch mode
- 2) Deeper pipelining on the 60x bus, programmable to max depth of 2, 3 or 4
- 3) Number of BATs is increased from 4 to 8 each for I and D
- 4) Addition of the HID4 register (SPRN = 1011) to control the new features.
- 5) TAU functionality is eliminated (but the THRM1-3 regs remain)
- 6) PLL configuration (processor-to-bus frequency ratio) expanded
- 7) Several changes to the signal pins - DRTRY, TLBISYNC, PLL_CFG
- 8) Several Gekko errata are fixed on Broadway.
- 9) The PVR is initially 0x00087100 on Broadway.
- DD2.0 (final)
Source: clkspeed.dol in RVL_UJI_DIAG