Technical information

Serial Solutions Using NewBIOS
stop
end if
C Go again for COM4
registers.ah = 16#AD
registers.bx = com4addr
registers.dx = 3
call intrpt (16#14, registers )
NewBIOS Default Settings.________________________
When NewBIOS is installed the addresses and IRQ lines
associated with each port are as shown in below.
Figure 4-1 NewBIOS Defaults.__________________________
Port I/O Address IRQ Line
COM1 As ROM BIOS (see note 1) 4 (see note 3)
COM2 As ROM BIOS 3
COM3 As ROM BIOS 3
COM4 As ROM BIOS 3
COM5 0 (see note 2) 3
COM6 0 3
COM7 0 3
COM8 0 3
COM9 0 -1 (see note 4)
COM10 0 -1
COM11 0 -1
COM12 0 -1
COM13 0 -1
COM14 0 -1
COM15 0 -1
COM16 0 -1
Notes:______
1) The ROM BIOS services maintain a list of addresses for
COM1 to COM4 (at address 0040:0000), which NewBIOS
copies into its own lists when it is installed. Changes to
COM1 to COM4 affected via NewBIOS are also written to
the ROM BIOS list of addresses.
Page 66 Chapter 4