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PC Workstations
Basic Evaluation Criteria

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Modern high-end computer drafting packages and 3-dimensional drawing, animation and rendering programs place significant demands on the personal computers typically used by the engineering profession. Due to the rapid pace of change in the computer industry, it is very difficult to recommend the "best" computer configuration. Intel's fastest workstation capable CPU can become an "entry level" model within the span of a few months. It is possible, however, to establish some basic criteria which will aid in choosing equipment which will be useful for a few flavor of the month cycles.

[ Processor | System Memory | Graphics Card | Hard Disk ]


Introduction

 The basic system configuration should be assembled for the purpose of providing a fast and efficient platform that iis capable of supporting the demands of advanced CAD and 3D Graphics packages. Since these applications must process very large amounts of data, it is imperative that each computer component is capable of helping to increase overall system speed and performance.

Central Processing Unit (CPU)

The corner stone of a quality system is the CPU. When this article was orginally written, the fastest x86 based CPU was Intel's 90-Mhz Pentium or P5 chip. Since that time, Intel has released 100-Mhz, 120-Mhz, and 133-Mhz versions of the chip. In addition to the ever increasing clock speeds, Intel is already introducing its next generation P6 or "Pentium Pro."

[NOTE: Although the following statistics refer to nearly "ancient" computer components, the point about increased CPU speed is still relevant.]

The 90-Mhz Pentium chip from Intel was one of the fastest processors available in late 1994. According to Intel's literature, the Pentium or "P5" chip is capable of executing floating-point instructions approximately 5 to 10 times faster than a 33-MHz 486DX. This statistic is important because the majority of calculations which are performed by CAD and 3D Graphics packages are floating point calculations. Thus, a complex AutoCAD drawing regeneration which takes 50 minutes on a 486 can be completed in 10 minutes or less on a Pentium machine. This amounts to a time savings of nearly three quarters of an hour. Intel also describes the performance of a 90-MHz Pentium by providing "iCOMP" values. These values represent a simplified measure of relative Intel microprocessor performance. A 66-MHz 486DX2 has an iCOMP value of 297 and a 90-MHz Pentium has a value of 735. In general, a fast CPU provides the opportunity to replace non-productive, costly "down time" with profit producing work.

Graphics Card

The graphics card is another important component because it is the link which transforms the numerical data into a comprehensible image. Since a graphics card is optimized to deal with "graphics instructions," it is capable of handling tasks such as drawing polygons and executing "raster" operations faster than the CPU. Furthermore, the card serves to reduce the "load" on the CPU by moving a block of calculations to a separate processor. When choosing a graphics card two important area must be considered. First, the amount and type of memory (ie. DRAM, VRAM, WRAM) the card contains will affect the number of supported video modes and the speed of the display. DRAM memory is typically the slowest of the three type since it can only read or write data in one operation. VRAM and WRAM are capable of reading and writing data simultaneously. WRAM is supposed to be cheaper to manufacture than VRAM. VRAM is a solid performer which is used on a number of top of the line cards. The second consideration is the bandwidth of the card. A 64-bit card is capable of transfering more data than a 32-bit card.

System Memory

The system's RAM and hard disk capacity form the final building block. These pieces of hardware basically store the data which is processed by the CPU. If a program cannot temporarily store the needed set of data in RAM, then it will store it on a hard disk. Since accessing data from RAM is faster than accessing it from the hard disk, it is advantageous to have as much RAM as possible. The savings in data access times will lead to a dramatic improvement in overall system performance.

Hard Disk

Finally, the system requires sufficient hard disk capacity to permanently store the operating system, programs, data files, and various temporary files which are created by executing programs. This free space becomes critical for when dealing with graphics packages. For example, an AutoCAD rule of thumb suggests that a hard disk should have an amount of free space which is equal to 4 times the size of the original drawing file. Thus, a 25 Mb drawing would require 100 Mb of free disk space. Another rule of thumb states that you'll never have enough hard disk space. A 1 Gb hard can become filled in a very short period of time. This is usually due to a combination of factors such bloated application programs, poor file management, and file systems such as FAT which waste disk space.

The type of hard disk which should be installed in a system is determined by examining two basic issues. First, the appropriate drive interface, IDE or SCSI, must be chosen, and second, the required capacity must be calculated.

The Integrated Drive Electronics (IDE) interface is characterized by the fact that the drive electronics are built directly into the hard disk. The controller card for the IDE drive simply serves to provide a link between the hard disk and the motherboard. IDE drives are popular because they are fairly fast, reliable, easy to install, and relatively inexpensive. IDE drives have two major drawbacks. First, they can not address a single disk or partition greater that 528-Mb, and second, no more than two IDE drives can be installed in a system. Finally, most large capacity drives are "modified" IDE drives. These drives are known as Enhanced IDE drives (EIDE) and are capable of exceeding the limits created by the IDE standard.

The second type of popular drive interface is the Small Computer System Interface (SCSI). This drive interface is designed to support capacities of up to three gigabytes or more, and it has the capability of supporting multiple devices such as additional hard disks or CD-ROM drives. Typical multiple device support allows a user to daisy-chain or link up to seven devices. Finally, standard SCSI is much faster than standard IDE drives. The main problem with SCSI devices is that they are more expensive than comparable IDE drives and the installation process is more complicated. In general, SCSI interfaces are best suited for computers, such as file servers, which require massive amounts of hard disk space.

The issue of required drive capacity can be resolved rather simply. A user should purchase that largest capacity drive which is economically feasible. Modern programs have a tendency to require larger amounts of disk space with each revision. The current version of WordPerfect for Windows, for example, requires nearly 33 megabytes of disk space. This is a large amount of disk space for a program which used to be a simple word processor! Additional programs and data files can eat up file space quickly. The best solution to this never ending "real estate" problem consists of a large capacity hard drive and good file management. As a last resort, a user can use disk compression software to squeeze added space from a filled drive.

Conclusion

This basic criteria leads to the following system configuration:
  1. A Pentium or Pentium Pro processor running at the highest available clock speed. It is also a good idea to look for a system which is designed to allow for easy replacement of the CPU. A future CPU upgrade may extended the life of the machine.
  2. A minimum of 32 megabytes of system RAM. (EDO memory is preferable since it is supposed to give better peformance) Furthermore, the system should be capable of providing sufficient room for future expansion. A large amount of memory will help impove the performance of modern multi-tasking operating systems such as OS/2
  3. A 4 Mb graphics card which is capable of running efficiently at high resolutions (1024x768 or greater) and high color depths (ie. 65,000 or 16 million colors).
  4. A hard disk with a capacity of at least 1 gigabyte and a CD-ROM drive.


This concludes the basic coverage. Once you merge this basic criteria with your specific requirements, you should be able to create your master specification list. Research the market and find the best equipment which meets your needs. (The Computer Hardware section of the Useful Links area should help you get started). Finally, DON'T go out and buy equipment based SOLELY on price. You'll regret it in the long run.

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Please send comments, suggestions, and problem notices regarding this page to:
Marco J. Shmerykowsky.
Last updated on: 15 February 1997