OpenDevice

gain access to a device

This function opens the named device/unit and initializes the given I/O request block. Specific documentation on opening procedures may come with certain devices.

The device may exist in memory, or on disk; this is transparent to the OpenDevice() caller.

A full path name for the device name is legitimate. For example "test:devs/fred.device". This allows the use of custom devices without requiring the user to copy the device into the system's DEVS: directory.

All calls to OpenDevice() should have matching calls to CloseDevice()!

Devices on disk cannot be opened until after AmigaDOS has been started.

Starting with Kickstart 2.0 (V36) Tasks can safely call OpenDevice(), though AmigaDOS may open system requesters (e.g., asking the user to insert the Workbench disk if "DEVS:" is not online). You must call this function from an AmigaDOS Process if you want to turn off AmigaDOS requesters.

devName

requested device name

unitNumber

the unit number to open on that device. The format of the unit number is device specific. If the device does not have separate units, send a zero.

iORequest

the I/O request block to be returned with appropriate fields initialized.

flags

additional driver specific information. This is sometimes used to request opening a device with exclusive access.

error

Returns a sign-extended copy of the io_Error field of the IORequest. Zero if successful, else an error code is returned.

Prior to Kickstart 2.0 (V36), Tasks could not make OpenDevice() calls requiring disk access (since Tasks are generally not allowed to make dos.library calls). Now OpenDevice() is protected from Tasks.

AmigaDOS file names are not case sensitive, but Exec lists are. If the device name is specified in a different case than it exists on disk, unexpected results may occur. The same holds true if the device exists in memory and the device name is specified in a different case.

CloseDevice(), DoIO(), SendIO(), amiga.lib/BeginIO(), CheckIO(), AbortIO(), WaitIO()