SECTION 6
Conversions and Interfaces
6-64 PEN*KEY
R
6200/6300 Hand-Held Computer Programmer’s Reference Guide
INT 14h, Function AX = 0500h: Read Modem Control Port
4000API
Reads information from the modem control register.
On Entry:
AH = 05h
AL = 00h = Read from modem control register
DX = Communications port number (0, 1, 2)
On Return:
BL = Modem Control register value:
Bit 7 = Ignore modem control signals, COM1 only
Bits 6ć2 = Reserved
Bit 1 = Request to send (RTS)
Bit 0 = Data terminal ready (DTR)
AH = Line Status register (see values on page 6Ć61)
AL = Modem Status register (see values on page 6Ć61)
"
NOTE:
This is a nonstandard PC function. It may not be available in every PC BIOS. Use caution
where portability is a concern.
INT 14h, Function AX = 0501h: Write Modem Control Port
4000API
Writes specified information to the modem control register.
On Entry:
AH = 05h
AL = 01h = Write to modem control register
DX = Communications port number
BL = Modem Control register value:
Bit 7 = Ignore modem control signals, COM1 only
Bits 6ć2 = Reserved
Bit 1 = Request to send (RTS)
Bit 0 = Data terminal ready (DTR)
On Return:
AH = Line Status register (see values on page 6Ć61)
AL = Modem Status register (see values on page 6Ć61)
"
NOTE:
This is a nonstandard PC function. It may not be available in every PC BIOS. Use caution
where portability is a concern.
6. Conversions and
Interfaces
