Function 4407h Check Device Output Status

mov bx, Handle ;handle of file or device

mov ax, 4407h ;Check Device Output Status

int 21h

jc error_handler ;carry set means error

cmp al, 0FFh ;0FFh means file or device is ready

jne not_ready

Check Device Output Status (Function 4407h) determines whether a file or device is ready for output.

Parameter

Handle

Identifies the file or device to check.

Return Value

If the function is successful, the carry flag is clear and the AL register contains the output-status value. Otherwise, the carry flag is set and the AX register contains an error value, which may be one of the following:

Value

Name

0001h	ERROR_INVALID_FUNCTION
0005h	ERROR_ACCESS_DENIED
0006h	ERROR_INVALID_HANDLE

Comment

The meaning of the output-status value depends on whether the handle specifies a file or a device, as shown in the following table:

Status

Device

File

00h	Not ready	Ready
0FFh	Ready	Ready

For an output file, Check Device Output Status always returns Ready, even if the disk is full or there is no disk in the drive.