- [Supported config options](#supported-config-options)
  - [`0`: **BOOTLOADER\_SWITCH**](#0-bootloader_switch)
  - [`1`: **ROM\_WRITE\_ENABLE**](#1-rom_write_enable)
  - [`2`: **ROM\_SHADOW\_ENABLE**](#2-rom_shadow_enable)
  - [`3`: **DD\_MODE**](#3-dd_mode)
  - [`4`: **ISV\_ADDRESS**](#4-isv_address)
  - [`5`: **BOOT\_MODE**](#5-boot_mode)
  - [`6`: **SAVE\_TYPE**](#6-save_type)
  - [`7`: **CIC\_SEED**](#7-cic_seed)
  - [`8`: **TV\_TYPE**](#8-tv_type)
  - [`9`: **DD\_SD\_ENABLE**](#9-dd_sd_enable)
  - [`10`: **DD\_DRIVE\_TYPE**](#10-dd_drive_type)
  - [`11`: **DD\_DISK\_STATE**](#11-dd_disk_state)
  - [`12`: **BUTTON\_STATE**](#12-button_state)
  - [`13`: **BUTTON\_MODE**](#13-button_mode)
  - [`14`: **ROM\_EXTENDED\_ENABLE**](#14-rom_extended_enable)

---

## Supported config options

SC64 provides simple flashcart configuration by exposing various options settable by both USB and N64 side.
All options other than **BOOTLOADER_SWITCH** are preserved on console reset or power cycle (only when powered from USB).

| id   | name                    | type    | description                                                             |
| ---- | ----------------------- | ------- | ----------------------------------------------------------------------- |
| `0`  | **BOOTLOADER_SWITCH**   | *bool*  | Switches between bootloader and ROM mapping on PI address `0x1000_0000` |
| `1`  | **ROM_WRITE_ENABLE**    | *bool*  | Enables write access to ROM section                                     |
| `2`  | **ROM_SHADOW_ENABLE**   | *bool*  | Enables overlapping last 128 kiB of ROM section by flash memory         |
| `3`  | **DD_MODE**             | *enum*  | Enables 64DD register/IPL access                                        |
| `4`  | **ISV_ADDRESS**         | *dword* | Sets IS-Viewer 64 watch address                                         |
| `5`  | **BOOT_MODE**           | *enum*  | Controls bootloader behavior                                            |
| `6`  | **SAVE_TYPE**           | *enum*  | Sets supported save type                                                |
| `7`  | **CIC_SEED**            | *word*  | Sets CIC seed value passed by bootloader to IPL3                        |
| `8`  | **TV_TYPE**             | *enum*  | Sets TV type value passed by bootloader to IPL3                         |
| `9`  | **DD_SD_ENABLE**        | *bool*  | Controls 64DD block request passing to USB or SD card                   |
| `10` | **DD_DRIVE_TYPE**       | *enum*  | Sets 64DD drive type                                                    |
| `11` | **DD_DISK_STATE**       | *enum*  | Sets current 64DD disk state                                            |
| `12` | **BUTTON_STATE**        | *bool*  | Gets button press value                                                 |
| `13` | **BUTTON_MODE**         | *enum*  | Sets button press behavior                                              |
| `14` | **ROM_EXTENDED_ENABLE** | *bool*  | Enables access to extended ROM memory located in flash                  |

---

### `0`: **BOOTLOADER_SWITCH**

type: *bool* | default: `1`

- `0` - ROM data is mapped on PI address `0x1000_0000`
- `1` - Bootloader data is mapped on PI address `0x1000_0000`

Used internally to remap ROM data after bootloader is loaded.

---

### `1`: **ROM_WRITE_ENABLE**

type: *bool* | default: `0`

- `0` - ROM write access is disabled
- `1` - ROM write access is enabled

Used by homebrew applications to freely replace data in SDRAM from N64 side.

---

### `2`: **ROM_SHADOW_ENABLE**

type: *bool* | default: `0`

- `0` - Last 128 kiB of ROM section is mapped to SDRAM
- `1` - Last 128 kiB of ROM section is mapped to flash

Last 128 kiB of SDRAM is shared between ROM data and SRAM/FlashRAM save data.
Use this setting for applications requiring all of ROM section space including last 128 kiB.
Check [PI memory map](./01_memory_map.md#pi-memory-map) for more information.

---

### `3`: **DD_MODE**

type: *enum* | default: `0`

- `0` - 64DD support is disabled
- `1` - 64DD registers are mapped on PI address space
- `2` - 64DD IPL is mapped on PI address space
- `3` - Both 64DD registers and IPL are mapped on PI address space

Use this config for setting level of 64DD emulation.

---

### `4`: **ISV_ADDRESS**

type: *dword* | default: `0x0000_0000`

- `0x0000_0000` - IS-Viewer 64 is disabled
- `0x0000_0004` to `0x03FF_FFFC` - IS-Viewer 64 is enabled

Sets IS-Viewer 64 listening address starting from ROM base.
For most applications this offset is fixed at `0x03FF_0000`.
Address must be 4-byte aligned. Command will return error when setting incorrect value.
Small number of games have support for changing this address (for example debug builds of TLoZ: MM).

---

### `5`: **BOOT_MODE**

type: *enum* | default: `0`

- `0` - Load menu from SD card
- `1` - Attempt to boot application loaded in ROM section
- `2` - Attempt to boot 64DD IPL
- `3` - Direct mode, skips bootloader entirely

Use this setting to change boot behavior.
Value `3` (direct boot) will always keep **BOOTLOADER_SWITCH** option disabled.

---

### `6`: **SAVE_TYPE**

type: *enum* | default: `0`

- `0` - All saves are disabled
- `1` - EEPROM 4 kib save is enabled
- `2` - EEPROM 16 kib save is enabled
- `3` - SRAM 256 kib save is enabled
- `4` - FlashRAM 1 Mib save is enabled
- `5` - SRAM 768 kib save is enabled

Use this setting for selecting save type that will be emulated. Only one save type can be enabled.

---

### `7`: **CIC_SEED**

type: *word* | default: `0xFFFF`

- `0x0000` to `0x01FF` - Specified CIC seed/version value will be used
- `0xFFFF` - CIC seed/version value will be autodetected

Use this setting to force specific CIC seed/version.
Lower 8 bits represents CIC seed and 9th bit represents CIC version.
By setting value `0xFFFF` bootloader will try to guess needed values from loaded ROM IPL3.
This setting is not used when **BOOT_MODE** is set to `3` (direct boot).

---

### `8`: **TV_TYPE**

type: *enum* | default: `3`

- `0` - PAL TV type will be used
- `1` - NTSC TV type will be used
- `2` - MPAL TV type will be used
- `3` - TV type will be autodetected

Use this setting to force specific TV type.
By setting value `3` bootloader will try to guess TV type from loaded ROM header.
This setting is not used when **BOOT_MODE** is set to `3` (direct boot).

---

### `9`: **DD_SD_ENABLE**

type: *bool* | default: `0`

- `0` - 64DD block requests are passed to USB interface
- `1` - 64DD block requests are passed to SD card

Use this setting to change where 64DD emulation will be passing incoming block R/W requests.
For more information about 64DD and USB request passing check [sc64.py](../sw/pc/sc64.py#L636) implementation.

---

### `10`: **DD_DRIVE_TYPE**

type: *enum* | default: `0`

- `0` - Retail 64DD drive type ID is selected
- `1` - Development 64DD drive type ID is selected

Use this setting to change 64DD drive type emulation.

---

### `11`: **DD_DISK_STATE**

type: *enum* | default: `0`

- `0` - 64DD disk state is set to ejected
- `1` - 64DD disk state is set to inserted
- `2` - 64DD disk state is set to changed

Use this setting to change 64DD current disk state.

---

### `12`: **BUTTON_STATE**

type: *bool* | default: `x` | **read-only**

- `0` - Button is not pressed
- `1` - Button is pressed

This is special read-only option for getting button press state.
Setting this option will return error.

---

### `13`: **BUTTON_MODE**

type: *enum* | default: `0`

- `0` - Button press does nothing
- `1` - Button press raises N64 interrupt
- `2` - Button press sends USB packet
- `3` - Button press changes 64DD disk

Use this setting to change button behavior.
Regardless of this setting button state can always be checked by reading **BUTTON_STATE** config.

---

### `14`: **ROM_EXTENDED_ENABLE**

type: *bool* | default: `0`

- `0` - ROM extended PI access is disabled
- `1` - ROM extended PI access is enabled

Use this setting to enable PI access for extended ROM data located inside flash memory.