Difference between revisions of "Hardware/Starlet"
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Hallowizer (talk | contribs) (→Exceptions: completed the table and described some IOS usage) |
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| 0 | | 0 | ||
| v_reset | | v_reset | ||
| − | | Hardware reset | + | | Hardware reset. Typically the entrypoint for official software. |
|- | |- | ||
| 1 | | 1 | ||
| v_undf | | v_undf | ||
| − | | Undefined instruction, used | + | | Undefined instruction, used as handler for [[IOS/Syscalls|IOS syscalls]] |
|- | |- | ||
| 2 | | 2 | ||
| v_swi | | v_swi | ||
| − | | | + | | SVC/SWI instruction, used for [[IOS/Syscalls#Syscalls_.28via_ARM_syscall_instruction.29|IOS SWI syscalls]] |
|- | |- | ||
| 3 | | 3 | ||
Revision as of 08:05, 27 September 2022
The Hollywood includes an ARM9 core to handle I/O and security, nicknamed the Starlet by fail0verflow, but internally known as the IOP, short for Input/Output Processor. This is a very interesting piece of hardware, as it basically does everything that makes a Wii different from a GameCube.
The Starlet contains an internal 96KB SRAM; if IOS needs more memory, it can lock part of MEM2 to prevent Broadway access.
Note: this page is incomplete. Please expand it as you see fit!
Specs
- NEC ARM926EJ-S SoC. See also ChipWorks.
- Big endian for compatibility with the Broadway
- ARM and thumb instruction set
- Clocked at 243MHz (Hollywood clock)
Exceptions
Exception vectors are located at ffff0000. Each exception is given 4 bytes, and usually branches elsewhere.
| Index | mini name | Description |
|---|---|---|
| 0 | v_reset | Hardware reset. Typically the entrypoint for official software. |
| 1 | v_undf | Undefined instruction, used as handler for IOS syscalls |
| 2 | v_swi | SVC/SWI instruction, used for IOS SWI syscalls |
| 3 | v_instr_abrt | Instruction abort |
| 4 | v_data_abrt | Data abort |
| 5 | v_reserved | Reserved |
| 6 | v_irq | IRQ |
| 7 | v_fiq | FIQ |
Boot
- See also: boot process
Starlet is the first processor to run code in the Wii.
- Starlet boots from an internal Mask ROM, BOOT0 (about 1300 bytes of code out of 4K possible)
- boot0 decrypts, verifies, and runs the first few blocks of NAND, BOOT1 (up to the first 48 pages of flash)
- boot1 locates, loads, decrypts, verifies, and runs BOOT2
- boot2 bootstrap then loads the embedded ELF file
- boot2 starts the IOS
- IOS loads code into the EXI buffer and bootstraps the Broadway
Links
More information about the Starlet:
- ARM926EJ-S Technical Reference Manual - CPU, MMU, Cache specs and programmer's interface
- ARM9EJ-S Technical Reference Manual - CPU specs and programmer's interface
- ARM Architecture Reference Manual - Documentation about the ARMv5 architecture.
- IOS - the OS that runs on the Starlet and handles calls from the Broadway during game execution and while in the system menu.
- ARM Binaries - the formats used for Starlet executable code
- WAD Files are used for BOOT2 and the IOS
- Patent for Starlet and IOS