Chapter 8 - Using MS-DOS
8-40
PL-5910 Series User Manual
Operation
Input
Output
Setting RS-232C line
mode
AH =
AL =
DX =
00h
Line mode/Parameter
Bits 7, 6, 5: Baud rate
Bits
0, 0, 0: 110 Baud
Bits
0, 0, 1: 150 Baud
Bits
0, 1, 0: 300 Baud
Bits
0, 1, 1: 600 Baud
Bits
1, 0, 0: 1200 Baud
Bits
1, 0, 1: 2400 Baud
Bits
1, 1, 0: 4800 Baud
Bits
1, 1, 1: 9600 Baud
Bits 4 & 3: Parity
Bits
X, 0: No parity
Bits
0, 1: Odd parity
Bits
1, 2: Even parity
Bit 2: Stop bits
Bit
0: 1 bit length
Bit
1: 2 bit length
Bits 1 & 0: Word length
Bits
1, 0: 7 bits
Bits
1, 1: 8 bits
Port No.
Sending 1-byte data
AH =
AL =
DX =
01h
Data to send
Port No.
AH = Line control status
Bit 7: Time over error
Bit 6: Transmission shift register empty
Bit 5: Transmission hold register empty
Bit 4: Break detected
Bit 3: Framing error
Bit 2: Parity error
Bit 1: Overrun
Bit 0: Data ready
Receiving 1-byte data
AH =
DX =
02h
Port No.
AL =
AH =
Received data
Line control status
Reading
communication port
status
AH =
DX =
03h
Port No.
AL =
AL =
Line control status
Modem status
Bit 7: Carry detected
Bit 6: Call signal received
Bit 5: Data-set ready
Bit 4: Transmission enabled (CTS)
Bit 3 - 0: Not in use
Operation
Input
Output
Wait time check
AH =
AL =
ES:BX =
CX:DX =
83h
00h: Interval timer start
01h: Interval timer stop
End flag address
Wait time in 1 µ sec units
CY =
=
0: Successfully completed
1: Error
INT 15h Other System Services
INT 14h RS-232C
