Technical information

Serial Solutions Pasterm

( Data > 3 )

THEN

Exit; { Bad Data number}

CH := Data;

{ Check Baud rate}

( Baud < 0 ) OR

( Baud > 11 )

THEN

Exit; { Bad Baud number}

CL := Baud;

AH := $4; { service 4, extended initialise}

{ Do initialisation}

Intr($14, ioregs); {Int 14H is BIOS Asynchronous services

interrupt}

BIOS_X_Init := true; {This service does not generate any error

codes}

END;

BIOX_X_Init uses the extended initialise service supplied

as part of NewBIOS to set up the port. It first checks that the

function parameters are valid. See chapter "NewBIOS

Reference", service 4. The parameters are stored in the Registers

variable ioregs, which is used to specify the parameters to Intr.

The chapter "Using NewBIOS" explains the use of Intr in Turbo

Pascal.

BIOS_X_Init returns a true flag 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 a false flag is

returned and the serial port is left alone.

Fitting The Parts Together.________________________

The main block of Pasterm is shown in Figure 9-6.

Page 148 Chapter 9