Int 21H Function 44H Subfunction 03H
◄Summary► ◄Notes► ◄Back►
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▀ If supported by the driver, this subfunction can be used to request
hardware-dependent operations (such as setting baud rate for a serial
port) that are not supported by other MS-DOS function calls.
▀ Character device drivers are not required to support IOCTL Subfunction
03H. A program can test bit 14 of the device information word returned
by IOCTL Subfunction 00H to determine whether the driver supports this
subfunction. If Subfunction 03H is requested and the driver does not
have the ability to process control data, control returns to the program
with the carry flag set and error code 0001H (invalid function) in
register AX.
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