(or 300 baud) using BASIC language instructions with the programs previously
shown. If it is not possible to dedicate the controller to inputting from the modem,
it is recommended that the service request (SRQ) function be implemented using an
assembly or machine language subroutine.
APPLICATIONS
For PET-to-PET telecommunications, the following
program may be used at each terminal:
5PRINT"THIS PROGRAM FOR PET-
COMMUNICATION" TO-PET
10 D=5:0PEN D.D
20 C$=CHR$(13)
30 GET#D.A$:IF ST<>0 THEN 100
40 A=ASC(A$) AND 127
50 IF A>96 THEN A=A AND 223
60 IF A=34 THEN A=39
70 PRINT"Cl"CHR$(A)"a";
80 IF A$=C$ THEN PRINT ">";
100 B=FRE(0)
110 GET A$:IF A$="" THEN 30
120 A=ASC(A$):IF A>127 THEN A= AAND 31
130 PRINT A$;
140 IF A$=C$ THEN PRINT "Q>
5
"
;
150 PRINT#D,CHR$(A);
160 GOTO 30
170 END
NOTE: Received messages are shown in reverse, i.e.,
dark letters on abright background.
The following procedure is recommended:
1
.
This transmission is quite susceptible to noise
or vibration at the acoustic coupler. Isolate the
modem from any such mechanical shock.
2. Start with both units in Full Duplex and with
modem power off.
3. Load PET-to-PET program.
4. Establish the telephone link. Agree on which
party shall be ORiginate. The other will be
ANswer.
5. Place telephone handset into modem receptacle.
Cord end is in modem away from controls and
indicators.
6. Switch modem power switch to ORiginate or
ANswer as agreed.
7. Type RUN and RETURN key. Check that CRX
indicator is on. The channel is now ready for
use.
The program shown operates as follows:
Line 10 opens afile for logical device number
5, which is^e modem, to set it up for com-
munication. Line 20 introduces the carriage
return character which is printed on the display
as a"prompt" character at the beginning of the
next line and serves as amessage saying "over."
Line 30 checks for input from the other party
and line 110 checks for akeyboard character
to be output to the other party. Lines 40, 50,
and 120 change shifted characters to control
characters. Line 60 reassigns quote character
{") to (').
For communication with ASCI Icompatible systems
such as the Source or Micronet, the following pro-
gram may be used:
5PRINT"THIS PROGRAM TO COMMUNICATE WITH NET"
10 D=5:0PEN D.D
20 GET#D,A$:IF ST<>0 THEN 100
30 A=ASC(A$) AND 127
40 IF A>96 THEN A=A AND 223
50 PRINT CHR$(A);
60 GOTO 20
100 GET A$:IF A$="" THEN 20
110 A=ASC(A$):IF A>127 THEN A=A AND 31
120 PRINTED, CHR$(A) ;:GOTO 20
130 END
The following procedure is recommended:
1. Start with the modem in the Full Duplex mode
and with modem power off.
2. Load network communications program.
3. Establish the telephone link. After acarrier
tone is received from the network, insert hand-
set into the modem receptacle. Cord end is in
modem away from controls and indicators.
Switch modem power switch to ORiginate. The
CRX indicator should go on.
Type RUN and press RETURN key several
times. The channel is now ready for use in
accordance with the network protocol.
6. If acontrol character is required, use ashift
character. If ESCAPE is required, use ashift I.
For program operation notes, see notes on
PET-to-PET program.
4.
5.
