SECTION 6
Conversions and Interfaces
6-62 PEN*KEY
R
6200/6300 Hand-Held Computer Programmer’s Reference Guide
INT 14h, Function AH = 01h: Transmit a Character
BIOS, 4000API
Transmits the AL character via the DXĆspecified communications port. DTR and
RTS are raised, and DSR and CTS are expected within a timeout period specified
by an array at 40:7C. Once DSR and CTS are received, the character to be sent
is placed in the transmit buffer register. The value of the Line Status Register is
returned in AH.
On Entry:
AH = 01h
DX = Communications port number
AL = Character to be sent
On Return:
AH = Line Status register (see values on page 6Ć61)
INT 14h, Function AH = 02h: Receive a Character
BIOS, 4000API
Receives a character in AL via the DX specified communications port. DTR is
raised, RTS is dropped and DSR is expected within a timeout period specified by
a 40:7C array. When DSR is received, a character is expected in the receive
buffer in the timeout period. If a timeout occurs, the timeout bit is set in AH. If
a character is received, it is returned in AL. The Line Status Register value is
returned in AH.
On Entry:
AH = 02h
DX = Communications port number
On Return:
AH = Line Status register (see values on page 6Ć61)
AL = Character received
"
NOTE:
For Transmit a Character and Receive a Character, DTR and RTS are raised and DSR
and CTS are expected within a timeout period specified by an array at 40:7C.
INT 14h, Function AH = 03h: Read Communications Port Status
BIOS, 4000API
Returns current Line and Modem status for DXĆspecified COM port. AH returns
Line Status Register value. AL returns Modem Status Register value.
On Entry:
AH = 03h
DX = Communications port number
On Return:
AH = Line Status register (see values on page 6Ć61)
AL = Modem Status register (see values on page 6Ć61)
6. Conversions and
Interfaces
