Choosing a Windows-capable system - Penn Printout, Apr 1992

The University of Pennsylvania's Online Computing Magazine

April 1992 - Volume 8:7

Buy long! Choosing a Windows-capable system

By Don Montabana

The June 1990 release of Windows 3.0 provided a much needed kick start to the evolution of DOS-based computing. While the Windows operating environment is by no means flawless, Windows 3.0 is a usable product that may, in fact, live up to Microsoft's assertion of increased user productivity. A much improved new release, version 3.1, will be available by the time this article appears.

Though Windows is not the only competitor in the struggle for operating system control-the other major player is IBM's OS/2 2.0 graphical operating system-it owns the lion's share of the market. Whether you choose Windows or OS/2, the net effect is the same: You need to move up to much more powerful computer hardware in order to effectively use either of these operating systems and their powerful new applications. And even if you are currently using a high-quality text- based word processor like WordPerfect, you would be selling yourself short if your next system were not capable of handling one of the windowed desktop environments.

Some assembly required

Let's assemble on paper a Windows-capable system-one that will provide acceptable performance and can at the same time exploit the functionality and power of these graphical user interfaces (GUIs). Note that the developers of Windows have published technical minimums for processor, memory, and hard disk requirements. Be aware, however, that they are just that-technical minimums. The CRC's experience is that much of what you would buy a graphical interface for would be lost if you adhere to these minimums.

In assembling a Windows-capable system there are five relevant features to consider: the central processing unit (CPU), memory (primary and cached), the hard disk, the video controller and monitor, and the math coprocessor. The overall performance of the system will ultimately be determined by both overall system design and the application(s) that are running. The following are the features and characteristics you should be alert for when considering systems in this category. If better performance is what you're after, then the operative terms with respect to the recommendations below are faster or bigger.

Processor

If a single component had to be selected as the most important, the microprocessor would top the list. On the basis of raw computing power alone, the higher the speed of a given class of processor (measured in MHz), the faster that computer will operate. The CRC recommends that you consider two major families of microprocessors for running Windows: the 80386 and the 80486. Within each family there are two to three distinct types, each offered at several different speeds. The minimum for acceptable performance is an 80386SX-based system in the 20 to 25 MHz range. If you are looking for better performance, you should consider moving up to an 80486-based processor.

A feature found today in all 80486-based microprocessors and in one 80386SX-based processor from IBM (the 80386SLC), is a built-in 8 Kbyte memory cache, in which repeatedly requested data normally found in main system memory (RAM) is stored. While the size of the cache may seem small, the fact that this cache is an integral part of the processor means that it runs at the speed of the microprocessor, making it a real performance booster. A built-in cache does not exist for 80386-based processors, although some manufacturers provide for an optional external hardware cache.

Random access memory

The two concerns with respect to memory are having sufficient memory to handle the heavy demands that a graphical environment places on system resources and the speed of the memory. For GUI-based systems the minimum the CRC recommends is 4 Mbytes of 80 nanoseconds (nsec) or faster memory. This will allow you to run Windows 3.x, at least two full-sized applications, and your base DOS operating system, which should be DOS 5.0 for maximum benefit (see "High Five!" in Penn Printout, December 1991). If you wish to run more than two applications concurrently, you should increase memory to 6 to 8 Mbytes. As a good rule of thumb, remember that the more memory you have installed, the better the performance and the greater the functionality you can expect from your system-and with memory prices at an all time low, additional memory beyond the 4 Mbyte minimum is strongly recommended.

Hard disk

Like microprocessors, hard drives have gotten faster and less expensive per Mbyte of storage. The current standards for performance and reliability are IDE (Integrated Drive Electronics) hard drives, in which the drive and its controlling electronics are physically connected, or the increasingly popular SCSI (Small Computer Systems Interface) hard drives, which offer fast data-transfer rates and the ability to chain several devices from a single port. We recommend either type of drive in the 80 to 120 Mbyte size range with access times of 20 milliseconds (msec) or less and data-transfer rates (continued on next page) 10 Mbits/sec or more. Because GUIs demand a lot of hard disk space and are also disk-intensive, again the rule is that larger and faster is better.

Video

To complement the system we're assembling you will also need to specify, at a minimum, a 16-bit VGA (Video Graphics Array) high- resolution (640 x 480 pixels) adapter. It is not uncommon today to see the video adapter built onto the system board and offering multiple levels of resolution and color support. The high-resolution levels commonly seen today, besides VGA, are Super VGA (800 x 600 pixels) or "Ultra" VGA (1024 x 768 pixels).

The number of colors you can generate on screen depends on the amount of separate video memory (VRAM) you have installed on your system. At the recommended VGA level nearly all systems support a palette of 256 colors. To support this many colors at the higher Super or "Ultra" VGA resolution will usually require the purchase of additional video memory. Note that in general, the higher the resolution and the larger the number of supported colors, the slower screen redrawing will be-this is because there are simply that many more pixels with multiple attributes that have to be manipulated.

To accommodate the new GUI-based applications and keep multiple windows open at the same time, the interest in color monitors larger than the traditional 13-inch units has been on the increase. The most popular, and our recommended size at this time, is the 14-inch monitor, but new releases of 15- and 16-inch versions are proving to be quite popular as well. In a GUI monitor, look for a screen size of 14 to 16 inches; dot pitch resolution of .31 mm or lower; and non-interlaced screen refresh rates of 70 Hz or higher, which provide flicker-free viewing.

Math coprocessor

This is still a popular option if you use numerically intensive applications. Its presence will not affect the capable performance of a GUI itself, although both text and GUI-based applications that perform calculations (e.g., spreadsheets, CAD programs, statistical software, some drawing software) will show marked improvements. A math coprocessor will improve floating point calculations by a factor of 10 to 15. On 80386-based systems a math coprocessor is an optional purchase; 80486-based systems are available with the math coprocessor either enabled (80486DX series) or disabled (80486SX series).

CRC recommendations

A system that will serve you well for entry into the Windows graphical environment and for the next few years has these minimums:

20 to 25 MHz 80386SX-based processor
4 Mbytes 80 nsec or faster memory
80 to 120 Mbyte 20 msec or faster hard drive
VGA level graphics with a color palette of 256 colors; 14-inch color monitor with a .31 mm or smaller dot pitch and a 70 Hz or higher non-interlaced refresh rate

Sidebar 1: If "capable" is not enough

The main article restricts its discussion to "Windows-capable" minimums. If you're not new to Windows and know that you need additional performance to tame this demanding operating environment, we recommend the Intel 80486-based series of microprocessor. At present, a faster and more powerful processor provides a much improved price/performance ratio and is the most effective investment for each additional dollar spent.

Most appealing in the current mix of 486-based systems are those that incorporate the new "speed doubler" processors, which give you substantially more power for considerably fewer dollars than other 486- class processors. For the recently released speed-doubling 80486 DX2-50 processor, this means that certain operations external to the processor, such as reading and writing to memory, are processed at 25 MHz, but the processor operates internally at twice that speed-at 50 MHz. (Most other non-memory peripheral operations continue to run at their native speed, which is far slower than 25 MHz.) Although both reads and writes to memory are processed at 25 MHz, as much as 95 percent of memory reads can be made from the 8 Kbyte internal cache and memory management unit that runs at 50 MHz. Therefore, performance of the 486 DX2-50 is rated as showing a 70 percent improvement over a comparable 25 MHz 486 system and about a 35 percent improvement over a 33 MHz 486 system.

Sidebar 2: Taking the long view

Regardless of what your current needs may be, it is important that you look beyond the present to potential needs. Be careful not to lock yourself into a technological platform, such as the diminishing crop of 80286-based systems, whose performance you will quickly find unacceptable and whose capabilities you will outgrow within a year.

Computing technology is evolving continually and rapidly, with computing power doubling every 12 to 18 months while prices simultaneously decrease. Add to this the fact that as new graphically oriented software releases make better use of the full range of features of the present family of 80386 and 80486 microprocessors (and the soon-to-be released even faster and more powerful 80586 chip), greater demands will be placed upon your computer system. Take the long view-select a system that will not only provide the levels of performance you need currently, but will also allow for the inevitable growth in your computing needs.

DON MONTABANA is Manager of User Services for the Computing Resource Center.