INT 14 - SERIAL I/O - EXTENDED COMMUNICATION PORT CONTROL (CONVERTIBLE,PS)
AH = 05h
AL = 00h read modem control register
Return: BL = modem control register (see below)
AH = status
AL = 01h write modem control register
BL = modem control register
bit 0: data terminal ready
bit 1: request to send
bit 2: OUT1
bit 3: OUT2
bit 4: LOOP
bits 5-7 reserved
Return: AX = status
DX = port number
SeeAlso: AH=1Fh

See also: 1400

1405 - SERIAL I/O - EXTENDED COMMUNICATION PORT CONTROL (CONVERTIBLE,PS)