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From: logajan@ns.network.com (John Logajan)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: How do I detect the presence of a carrier?
Message-ID: <1990Oct20.042911.7249@ns.network.com>
Date: 20 Oct 90 04:29:11 GMT
References: <65827@iuvax.cs.indiana.edu>
Organization: Network Systems Corporation
Lines: 81

kclenden@silver.ucs.indiana.edu (Kevin Clendenien) writes:
>I actually want to know if
>I've lost the carrier during a modem connection.  Also, what do
>the parameters UCR, RSR, TSR, and SCR represent in the call to 
>the XBIOS when configuring the RS232 port?

Controlling the RS232 port from GFA Basic.  An actual example.

Void Xbios(15,7,0,&H88,1,1,-1) ! RS232 configuration/baud rate. (See below.)
Rem
Rem Configure RS232 - Xbios(15,baud,ctrl,ucr,rsr,tsr,scr).
Rem baud = 0/19200, 1/9600, 4/2400, 7/1200, 9/300, 13/110.
Rem ctrl = 0/None, 1/XOFF-XON, 2/RTS-CTS(doesn't work), 3/both.
Rem ucr = 8bits, 1stop, noparity.
Rem rsr = recv enabled.
Rem tsr = xmit enabled.
Rem scr = not used.
Rem

Note the use of -1, above, to RETAIN current variable settings.

0 19200
1 9600
2 4800
3 3600
4 2400
5 2000
6 1800
7 1200
8 600
9 300
10 200
11 150
12 134
13 110
14 75
15 50

ucr bits:
0 not used
1 0=odd 1=even parity
2 0=no parity 1=parity
3,4 (in 4,3 order -->) 00-sync,01-async/1stopbit,10-async/1.5,11-2stopbits
5,6 (6,5 order) 00-8bits,01-7bits,10-6bits,11-5bits.
7 0=direct clock, 1=divide by 16 (use div/16 to get correct baud rates!)

rsr bits:
0 1=receiver enable
1 1=syncronous strip?
2 1=start bit detected
3 1=break detected
4 1=frame error
5 1=parity error
6 1=overrun error
7 1=buffer full

tsr bits:
0 1=transmitter enable (else see state below!)
1,2 (2,1 order) 00=output high,01=high,10=low,11=loop back.
3 1=force break
4 end of transmission ?
5 auto turnaround ?
6 1=underrun error
7 1=buffer empty

scr:  Some sort of syncronous data i/o port.

Peek(&HFFFA01)

Bit 0: Centronics busy
Bit 1: RS232 data carrier detect - input   <<<<<----- *this is it* * * *
Bit 2: RS232 clear to send (CTS) - input
Bit 3: reserved
Bit 4: keyboard and MIDI interrupt
Bit 5: FDC and HDC interrupt
Bit 6: RS232 ring indicator
Bit 7: Monochrome monitor detect (1=color)

-- 
- John Logajan @ Network Systems; 7600 Boone Ave; Brooklyn Park, MN 55428
- logajan@ns.network.com, 612-424-4888, Fax 612-424-2853