Windows NT vs Windows 95 For Inspection Systems

Comparison of Execution Speeds for Windows 3.1, Windows 95 and Windows NT

The recent introduction of Windows 95^TM, the long-awaited PC-based 32-bit operating system, has prompted developers to reconsider their inspection system platforms. When properly configured, today’s PCs can be used for inspection tasks ranging from noncontact measurement of electronic components to PCB assemblies. Developers are realizing that today’s PCs, coupled with 32-bit operating systems, can offer similar or better performance than dedicated hardware or VME-based solutions, and at a substantially lower cost. Since Microsoft is the popular choice for developing on PC platforms, most developers are choosing between Windows NT^TM and Windows 95.

Maximizing Speed

The 32-bit operating systems are not new, but the performance and cost savings realized from these systems are. Today’s PC hardware can drive 32-bit operating systems at maximum speeds more cheaply and efficiently than ever before. Pentium-based machines with PCI buses and Intel Triton core logic chipsets give the performance and bandwidth needed for an ever-increasing number of imaging applications. The necessary PCI peripherals, such as frame grabbers, are plentiful, inexpensive and offer real-time transfer capabilities. And for applications where the processing power of the CPU is still not fast enough, dedicated image processing boards can be added to create systems to handle almost any inspection task.

The PCI bus provides fast transfers for the large amounts of data associated with imaging. But to keep the data moving, optimized chipsets such as the Intel Triton core are needed to tie the CPU and memory to the PCI bus. Faster RAM and better cache designs also assure that a system is running at optimum speeds.

For the compute-intensive demands of an inspection system, a 32-bit application provides a substantial performance gain over a 16-bit application. Both Windows 95 and Windows NT operating systems provide a good environment for realizing the 32-bit performance gains.

Why Microsoft?

Many developers of imaging systems are choosing Microsoft’s 32-bit operating system. Other 32-bit operating systems are available, but none offers the mass appeal of Windows NT or Windows 95. IBM OS/2 has received relatively little third-party support when compared to Windows. The UNIX platform has so many flavors that no clear standard has emerged.

The widespread acceptance of 16-bit Windows has established Microsoft as the mainstream operating system provider of choice. Microsoft also offers Visual C/C++, the most popular software development environment for Windows. Imaging libraries are also available to help speed up development of 32-bit applications for 32-bit Windows environments.

All of these reasons, combined with the features that 32-bit Windows operating systems have to offer, are leading developers to focus their choice on either Windows NT or Windows 95. The decision will be based on cost, architecture, performance and stability, as well as issues such as symmetrical multiprocessing and platform independence.

A computer to be used for an imaging application under Windows NT should have a fast Pentium processor, at least 24 MB of RAM and roughly 100 MB of hard disk space. In comparison, a Windows 95 system should have a fast Pentium processor, at least 16 MB of RAM and about 50 MB of hard disk space. Since Windows 95 requires less RAM and hard disk space, and sells for less, it costs less to configure a PC under Windows 95 than Windows NT.

Besides cost considerations, a developer must look at operating-system architecture. Windows NT was designed from the ground up as a true pre-emptive multitasking/multithreading 32-bit operating system. It offers a fully re-entrant design which guarantees that multiple tasks or threads have access to the operating-system resources during their time-share of the CPU.

Windows 95 can be described as a hybrid 32/16-bit operating system. To retain backward compatibility with 16-bit applications, some components of Windows 95 are still 16 bit. Consequently, some of its components are nonre-entrant.

Some tasks or threads may be denied access to the operating-system resources during their time-share of the CPU. The potential for this undeterministic behavior may jeopardize the efficiency of applications running under Windows 95.

Since Windows 95 has some 16-bit components, you would expect Windows NT to have better performance. Actually, both operating systems exhibit similar overall execution speeds depending on the application.

Under Windows 95, some 32-bit calls must be translated to 16-bit calls to interact with the 16-bit modules, which affects performance. Windows NT has more layers of software in its architecture, and this affects the performance of 32-bit applications running under Windows NT. The execution speed of the imaging operations using the 32-bit Matrox imaging library is roughly the same under Windows NT and Windows 95 (Figure 2).

Windows NT has been around for some time now and offers a more stable and secure operating environment with superior crash protection. Windows 95 is less robust and relatively new, and, as with any new software, bugs may be waiting to surface.

The stability and robustness of Windows NT is desirable for a development platform as well as for a reliable run-time system. Since Windows NT is a more robust environment to work in, it may save money in the long run because development stations and completed inspection stations running Windows NT may not crash as often as systems running Windows 95.

Multiprocessor support and platform independence are two more differences between these operating systems. Both features are provided with Windows NT, but not Windows 95. Multiprocessor support provides the opportunity for increased performance, and platform independence does not lock a developer to an Intel-based solution. Windows NT supports Intel x86, MIPS, Alpha and PowerPC-based computers.

The Final Word

Since Windows NT and Windows 95 can run imaging applications at basically the same speed, the decision to choose one over the other comes down to one of cost vs stability. For developers with a tight budget, Windows 95 is the less expensive solution. For developers of mission-critical systems, Windows NT is the right solution because of its robustness.

About the Author

Pierantonio Boriero is Technical Products Manager for the Imaging Products Group at Matrox Electronic Systems. He received a bachelor of electrical engineering degree from McGill University, and has previous experience as an Applications Engineer and Integration Specialist. Matrox Electronic Systems, Ltd., Imaging Products Group, 1025 St. Regis Blvd., Dorval, QC, H9P 2T4 Canada, (800) 804-6243.

Figure 2

Copyright 1995 Nelson Publishing Inc.

November 1995