CDVD N Commands
Parameters are in units of bytes and are little-endian. All N commands raise IRQ2 (bit 1 of CDVD I_STAT).
00h NOP
01h NOPsync
Params: None.
These commands do nothing? They do raise an IRQ upon their "completion".
02h Standby
Params: None.
Returns the read position to sector 0 and sets the drive status to PAUSED. Possibly also spins the drive if it's not spinning already?
03h Stop
Params: None.
Returns the read position to sector 0 and stops the drive. Seems to have a 166 ms delay?
04h Pause
Params: None.
Unknown what effect this has, from the perspective of emulation.
05h Seek
Params:
- 0-3 Sector position
Moves the read position to the indicated parameter.
06h ReadCd
Params:
- 0-3 Sector position
- 4-7 Sectors to read
- 10 Block size (1=2328 bytes, 2=2340 bytes, all others=2048 bytes)
Performs a CD-style read. Seems to raise bit 0 of CDVD I_STAT upon completion?
08h ReadDvd
Params:
- 0-3 Sector position
- 4-7 Sectors to read Performs a DVD-style read, with a block size of 2064 bytes. The format of the data is as follows:
| offset | size | description |
|---|---|---|
| 0 | 1 | Volume number + 0x20 |
| 1 | 3 | Sector number - volume start + 0x30000, in big-endian. |
| 4 | 8 | ? (all zeroes) |
| 12 | 2048 | Raw sector data |
| 2060 | 4 | ? (all zeroes) |
09h GetToc
Params: None?
Fetches the ToC from the disk, with a block size of 2064 bytes.