Hardware Reference
In-Depth Information
3 Using the command line
interface
This chapter outlines the facilities provided by the DOS operating system and
the command line interpreter (CLI) in particular. Emphasis has been placed on
those features which are of particular relevance to the engineer and software
developer as well as those who may be unfamiliar with what lies below the
Windows interface. If you are planning to develop applications that will run
on minimal systems (without the overhead imposed and restriction imposed
by Windows) or if you are developing
console applications
to run inside
the Windows environment time spent in getting to know the CLI (includ-
ing its peculiarities and foibles) can be instrumental in avoiding a variety of
pitfalls.
The need for an
operating system
Anyone who has made passing use of a microcomputer system will be aware of at
least some of the facilities offered by its operating system. Such an awareness is
developed by means of the interface between the operating system and the user;
the system generates prompts and messages, and the user makes an appropriate
response.
Within the familiar 'drag and drop' and 'point and click' interface provided
by Windows where there is no need to use a command language. This, of
course, is as it should be. As far as most end-users of computer systems are
concerned, the operating system provides an environment from which it is pos-
sible to launch and run applications, and to carry out elementary maintenance
of disk files. In such cases, the operating system is perhaps better described
as a
microcomputer resource manager
. As such, the operating system provides
an essential bridge between the user's application programs and the system
hardware.
In order to provide a standardized environment (which will cater for a vari-
ety of different hardware configurations) and ensure a high degree of software
portability, part of the operating system is hardware independent (DOS) whilst
the hardware dependent (BIOS) provides the individual low-level routines
required by the machine in question. Figure 3.1 illustrates this important point.
In the context of developing software for control and instrumentation appli-
cations, the software engineer needs to have a much deeper understanding of
the role of the operating system as a means of accessing, configuring, and
optimizing system resources. In addition, the software developer will need a
variety of tools and utility programs (including items such as editors, assem-
blers, linkers, and debuggers). These
development tools
work together with the
operating system to provide an environment which facilitates effective software
development.
