SECTION 6
Conversions and Interfaces
PEN*KEY
R
6200/6300 Hand-Held Computer Programmer’s Reference Guide 6-61
INT 14h, Function AH = 00h: Initialize COM Port
BIOS, 4000API, NGENMOD, NGENWAN
Programs Baud Rate and Byte Format Registers for selected port and returns
Line and Modem Status Register values. Enables UART power on intercept,
then passes call on to BIOS INT 14h entry point for initialization.
On Entry:
AH = 00h
DX = Communications port number (for NGENMOD or NGENWAN, this
could be 2 or 3)
AL = Initialization parameters:
Bits 7, 6, 5 Baud Rate
000 = 110 bps
001 = 150 bps
010 = 300 bps
011 = 600 bps
100 = 1200 bps
101 = 2400 bps
110 = 4800 bps
111 = 9600 bps
Bits 4, 3: Parity
00 = NO parity
10 = ODD parity
11 = EVEN parity
Bit 2 Stop Bits
0 = 1 stop bit
1 = 2 stop bits
Bits 1, 0 Word Length
10 = 7Ćbit word length
11 = 8Ćbit word length
On Return:
AH =
Line Status register:
7 = Timeout (if set, other bits are meaningless)
6 = Transmit shift register empty
5 = Transmit holding register empty
4 = Unused (break detected)
3 = Framing error
2 = Parity error
1 = Overrun error
0 = Data ready
AL =
Modem Status register:
7 = Carrier detect (CD)
6 = Ring Indicator (RI)
5 = Data Set Ready (DSR)
4 = Clear To Send (CTS)
3 = Delta CD
2 = Delta trailing edge RI
1 = Delta DSR
0 = Delta CTS
6. Conversions and
Interfaces
