CDVD I/O Ports

1F402004h Current N command (R/W)

Write to this register to send an N command. For a list of N commands, see CDVD N Commands

1F402005h N command status (R)

  • 0 Error (1=error occurred)
  • 1 Unknown/unused
  • 2 DEV9 device connected (1=HDD/network adapter connected)
  • 3 Unknown/unused
  • 4 Test mode
  • 5 Power off ready
  • 6 Drive status (1=ready)
  • 7 Busy executing NCMD CDVDMAN reads bits 6 and 7 to know when the device is ready to receive a command - bit 6 must be on and bit 7 must be off.

1F402005h N command param (W)

Send parameters for an N command here. This must be done BEFORE the N command has been sent via 1F402004h.

1F402006h CDVD error (R)

Any non-zero value indicates an error? Unknown what kind of errors are possible and what their values are.

1F402007h BREAK

Writing any value to this register sends a BREAK command to the CDVD drive, stopping execution of the current N command.

1F402008h CDVD I_STAT (R=Status, W=Acknowledge)

Status = Read I_STAT (1=Reason for IRQ) Acknowledge = Write I_STAT (1=Clear bit)

  • 0 Data ready?
  • 1 (N?) Command complete
  • 2 Power off pressed
  • 3 Disk ejected
  • 4 BS_Power DET?
  • 5-7 Unused

When a CDVD IRQ is raised on I_STAT, this register shows the reason for the interrupt. Bit 0 seems to be raised when a read command completes, but I'm not certain about this...

Unknown if bit 1 only applies to N commands, although this appears to be the case.

1F40200Ah CDVD drive status (R)

  • 0 Tray status (1=open)
  • 1 Spindle spinning (1=spinning)
  • 2 Read status (1=reading data sectors)
  • 3 Paused
  • 4 Seek status (1=seeking)
  • 5 Error (1=error occurred)
  • 6-7 Unknown

1F40200Bh Sticky drive status (R)

Exact same as 0xA, except the bits are "sticky" - the bits here are ORed with all previous drive states.

CDVDMAN compares 0xA and 0xB to know if the tray status has changed. SCMD 0x5 sets this register to reg 0xA's value.

1F40200Fh CDVD disk type (R)

  • 00h No disc
  • 01h Detecting
  • 02h Detecting CD
  • 03h Detecting DVD
  • 04h Detecting dual-layer DVD
  • 05h Unknown
  • 10h PS1 CD
  • 11h PS1 CDDA
  • 12h PS2 CD
  • 13h PS2 CDDA
  • 14h PS2 DVD
  • FDh CDDA (Music)
  • FEh DVDV (Movie disc)
  • FFh Illegal

1F402016h Current S command (R/W)

Write to this register to send an S command. For a list of S commands, see CDVD S Commands

1F402017h S command status (R)

  • 0-5 Unknown
  • 6 Result data available (0=available, 1=no data)
  • 7 Busy

1F402017h S command params (W)

Parameters must be sent BEFORE the S command is sent.

1F402018h S command result (R)

When an S command has finished executing, read the result here. Some S commands may require multiple reads.