AH = 03h: Get Serial Port Status

This function reports the status of the serial port and the modem-control lines connected to the serial adapter.

• Input: AH = 03h
  DX = Port# (0 = Built-In Serial Port)

• Output: AH = LSR Register (See "AH = 00h: Initialize Serial Port" on page 3-92.)
  AL = MSR Register (See "AH = 00h: Initialize Serial Port" on page 3-92)

• Error conditions: None reported
• Registers modified: AX