Technical information

Aterm Serial Solutions
cmp bl,1
ja bxi01 ;Bad stop bits
mov ch,databits
cmp ch,3
ja bxi01 ;Bad data bits
mov cl,baud
cmp cl,0BH
ja bxi01 ;Bad baud rate
mov dx,comno
cmp dx,15
ja bxi01 ;Bad port
mov ah,04H ;BIOS extended initialise
int com ;BIOS asynchronous services
clc
jmp short bxi02 ;exit good
bxi01:
stc ;exit bad
bxi02:
ret
bios_x_init endp ;done
;
Bios_x_init uses the extended initialise service supplied as
part of NewBIOS to set up the port. It works its way though the
port parameters, checking that each has a valid value. The
chapter "NewBIOS Reference" describes the parameters that
service 4, the extended initialise, requires.
Bios_x_init returns a carry false to show that is has
checked its parameters, found them to be ok, and used them to
set the serial port. If the parameters are bad then carry is
returned set and the serial port is left alone.
Fitting The Parts Together.________________________
The main part of ATERM is shown in Figure 8-7.
Chapter 8 Page 137