It has been five years since Microsoft Corporation overhauled Windows, the program that has become the standard ''interface'' between computer users and their machines. So for Microsoft, and for millions of customers, this is the year of Windows 95. After a number of delays, Microsoft promises the software will be on the shelves this August.
So what will the new program be like?
To get a sneak preview, I asked the Redmond, Wash., company for a test copy. Microsoft obliged by including me among thousands of ''beta testers.'' That's computer-industry jargon for people who try out early versions of a program and offer feedback so a company can fine-tune its software.
What follows are questions and answers, based on the test drive and information from Microsoft, plus interviews with others familiar with the product:
What is Windows 95?
It's the software Microsoft has developed to replace its DOS and Windows programs, which together manage most PCs sold today. DOS is the actual ''operating system,'' or controlling software, and Windows simplifies its use by substituting visual icons for the arcane text commands of DOS.
In Windows 95, Microsoft will combine operating system and visual interface in one.
Does that mean this is a revolutionary product? If so, what will happen to people who want to keep old software written for DOS?
Microsoft sees this as a ''landmark upgrade,'' but has committed itself to ''backward compatibility.'' That means that old applications programs, designed to run on DOS or on earlier versions of Windows, can still be used. Andrew Schulman, a programmer and author of books about DOS and Windows, says the 1990 release of Windows 3.0 was more revolutionary than Windows 95 will be. The new program's architecture, he says, is ''not all that different'' from its predecessors.
What's new in Windows 95?
Many things. Mr. Schulman says the cosmetic changes may outweigh the technical ones: ''I think mostly it's just going to look nicer, and I think that's very important.''
In addition to better aesthetics, users will be able to use longer file names, with spaces between words. Thus, a document could be called ''tax information for 1994'' instead of something like ''taxinf94.doc.''
This feature, long offered by rival software from Apple Computer, makes it easier to scan a list of files.
Other changes include:
r The Microsoft Network. It's an optional service for sending electronic mail, using the Internet computer network, and gathering information over the phone lines.
r ''Plug and play.'' Microsoft is trying to ease the burden on users when they connect their PCs to new devices, from CD-ROM drives to printers. The goal is to make the PC do the work of recognizing devices.
r ''Multitasking.'' A PC will be able to run more programs at once, with less risk of the computer ''crashing.''
r Better video playback from CD-ROM disks.
r The ability to run a new generation of programs, at 32 bits of information per second. Today Windows is designed for 16-bit applications.
Is it hard to make the transition from the old Windows to the new?
I found the improved help feature a great assistance, but it still takes time to learn new features. The basics will be fairly intuitive for people who are used to Windows 3.1.
Then should Windows 3.1 users switch to Windows 95?
That is not so easy to answer. For one thing, it depends on whether they need the new features. Also, Windows 95 requires a surprising amount of the machine's hard-disk memory (about 60 megabytes, three times the old Windows and DOS combo).
Users of newer PCs probably won't mind this. But I was happy to regain disk space by switching back to Windows 3.1.
Also consider time and money, including installation and training on the new program. PC Magazine recently estimated upgrade costs for Windows 95 at $200 or more per user in a workplace.
Finally, new programs have a reputation for having bugs that need to be corrected. A review released by InfoWorld magazine this week criticizes the program for crashing computers when too many applications are running simultaneously. Many computer experts expect further delays in the program's release to work out such bugs.
Is there serious competition to Windows?
For those buying a new computer, Apple is the most serious Windows competitor. Many experts have long favored the Macintosh operating system over Windows. Apple has begun licensing its Mac OS to other hardware manufacturers. And IBM makes the OS/2 operating system, which had a significant upgrade last fall.
Whether you should upgrade depends on whether you need the new features Windows 95 offers -- and whether your computer has the extra space on its hard disk.