Interrupt 2Fh Function 1607h

mov     bx, [DeviceID]  ; device identifier

mov     ax, 1607h       ; Device Call Out
int     2fh             ; Multiplex Interrupt

Device Call Out (Interrupt 2Fh Function 1607h) directs an MS-DOS device driver or TSR to provide information to the calling virtual device. Although the BX register specifies a device identifier, other registers may be used to specify the action to take.

DeviceID

Specifies the device identifier for a virtual device.

• The return value depends on the specific action requested.

This function typically is used by a virtual device to communicate with the driver or TSR that explicitly loaded the virtual device. It is up to the virtual device to supply a correct device identifier and any other parameters that specify what action to take. It is up to the driver or TSR to monitor Interrupt 2Fh, and respond to the function appropriately.

A virtual device can call this function at any time, either in real mode or after Windows has started.

See also Interrupt 2Fh Function 1684h Get Device Entry Point Address