Technical information

Using NewBIOS Serial Solutions
most users NewBIOS is loaded automatically when the
NewCOM.sys device driver is loaded in the CONFIG.SYS file.
This allows DOS, and hence applications, easy access to COM3
through to COM16. To do this the following line must be
included in the machine’s config.sys file:
device=newcom.sys
When the machine is powered on or reset DOS examines the file
called config.sys and installs the named file as a device driver.
An alternative method, for those very few users who do
not wish to use NewCOM is to run the program NewBIOS.com.
This checks for the presence of NewBIOS, and installs it if it is
not already present. The command is therefore:
c>newbios
The command ’newbios’ can be placed in the machine’s
autoexec.bat file so that every time the machine is rebooted
NewBIOS is installed.
Accessing Asynchronous Services.______________________________
Once installed the BIOS services can be accessed by user
programs written in many languages. This manual covers in
detail Assembly language, C, Turbo Pascal, GW-
BASIC/BASICA, QuickBASIC, Visual Basic for Dos and
Microsoft FORTRAN. We will first discuss the use of the
services from the viewpoint of assembly language programs and
then demonstrate how other languages do the same task. This
approach has been adopted because the nature of the BIOS
services means that a whatever language a programmer uses to
access them they must still appreciate how the services operate
at the machine level. Anyone already well acquainted with PC
assembly language will probably not need to be told how to use
the services, so this discussion will be aimed at the non-expert.
Anyone who is vaguely familiar with binary and hexadecimal
(written in the form ’XXH’) numbers should not find any
problems understanding it.
All BIOS services are interrupt routines. Interrupt routines
are run when a hardware interrupt occurs of when the 8086
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