'===========================================================================
' Subject: ACCESSING COM 3/4                  Date: 05/02/95 (00:00)       
'  Author: The ABC Programmer                 Code: QB, QBasic, PDS        
'  Origin: ACCESSING,COM3,COM4              Packet: MODEM.ABC
'===========================================================================
'Port Addresses: COM1  --  03F8h
'                COM2  --  02F8h
'                COM3  --  03E8h
'                COM4  --  02E8h

'EXAMPLE: Accessing COM3

   DEF SEG = 64       'move QuickBASIC segment pointer to BIOS data area
   POKE &H0, &HE8     'change com1: address in BIOS data area to com3:
   DEF SEG            'return to QB's DGROUP

   'open com3: by issuing open "com1:" command

   OPEN "COM1:9600,N,8,1" FOR OUTPUT AS #1


   PRINT #1, "ATDT555-5555"  'print to comm port
        
   CLOSE #1           'close comm port

   DEF SEG = 64       'point to BIOS data area
   POKE &H0, &HF8     'restore "com1:" address in BIOS data area to com1:
   DEF SEG            'return to DGROUP


'EXAMPLE: Accessing COM4

   DEF SEG = 64       'move QuickBASIC segment pointer to BIOS data area
   POKE &H2, &HE8     'change com2: address in BIOS data area to com4:
   DEF SEG            'return to DGROUP

'open com4: by issuing open com2: command

   OPEN "COM2:9600,N,8,1" FOR OUTPUT AS #1


   PRINT #1, "ATDT555-5555"  'print to comm port

   CLOSE #1           'close comm port

   DEF SEG = 64       'point to BIOS data area
   POKE &H2, &HF8     'restore com2: address in BIOS data area to com2:
   DEF SEG            'return to DGROUP