A longtime standard excels in a new environment

Autodesk's AutoCAD is the granddaddy of all drafting programs. The current incarnation, release 13c4 (R13), takes more than 200MB on a CD-ROM and ships with nearly 15 pounds of documentation (with more available only online at http://www.autodesk.com/products/autocad/r13c4/13c4idex.htm). The initial release of AutoCAD R13 included versions for UNIX, MS-DOS, and Windows 3.X. A few months later, Autodesk added a Windows NT version. I set out to discover how well NT and AutoCAD work together.

The Application
AutoCAD is a sophisticated design and drafting package for developing complex drawings. Screen 1 shows a drawing created using AutoCAD. The program supports 2D and 3D drawing and rendering, and sophisticated features such as solid modeling. Whereas a 3D rendering typically involves the cosmetics of a 3D object's surface, true solid modeling includes the attributes, such as mass and density, of real 3D objects. Unlike drawing files other programs create, an AutoCAD drawing is a full database of information that completely describes the objects ("entities," in AutoCAD terms) you draw. In fact, AutoCAD lets you link drawings to external databases so you can use drawings, for example, to generate a bill of materials. You can even use the information in an AutoCAD drawing to directly control automated machining tools.

AutoCAD has grown into its own industry--the AutoCAD Resource Guide that ships with the product has more than 300 pages of third-party add-ons, enhancements, and of course, T-shirts. Some of these add-ons, such as a calculator, provide simple features and others, such as 3D wire-frame unfolding and finite element analysis, are more sophisticated. You can bet that if a task has anything, even remotely, to do with CAD, someone has created an add-on for it in AutoCAD.

System Requirements
Everything about AutoCAD is heavy duty, which means if you want to seriously work with this program, you need a serious workstation. AutoCAD for NT runs on the Intel and Alpha platforms. Autodesk recommends at least 32MB of RAM; I found 40MB to be a comfortable minimum when working with most drawings. However, you might need 48MB or more for large complex drawings--particularly for rendering. A typical install requires 50MB of disk space and a generous swap file; fortunately disk space is cheap and plentiful. And don't even think about running AutoCAD on anything less than a fast Pentium. I didn't have time to test the program with a Pentium Pro, but as a pure 32-bit application that extensively uses floating point arithmetic, AutoCAD must work particularly well on this new processor.

Installation
Installing AutoCAD is easy. The program uses no external protection devices for the single-user US version. However, you'll need to dial a toll-free number to get an authorization code for each copy (this is pretty painless). The first time you run AutoCAD, you must go through a reasonably straightforward text-based configuration operation.

Running on NT
Once installed, AutoCAD ran flawlessly under NT with a noticeable advantage over previous versions: With the R13 release under NT, you can now open multiple AutoCAD sessions. Previously, AutoCAD ran only one session at a time: Windows 3.X does not support the multiple instance functionality. Because AutoCAD is a single document interface (SDI) application, the only way to open a second drawing is to open another AutoCAD session. So being able to run more than one session at a time is vital if you want to cut and paste from one drawing to another. Running two AutoCAD instances, however, requires patience or lots of RAM. I recommend an extra 8MB of RAM for each additional instance if you want to do a lot of cut and paste operations.

Just for fun, I ran half a dozen instances of AutoCAD; NT did this with no trouble. Each instance grabbed an extra 8MB to 10MB of swap-file space. Switching among the instances took between 3 and 4 seconds (including time to redraw) on my P90 system, which seemed reasonable. When I ran the same test under Windows 95, I couldn't get beyond the third instance without running into difficulties. The system either crashed or displayed a blank dialog (always a sign of resource problems).

Although AutoCAD runs well under NT, the program is not particularly well integrated with some advanced features of NT. For example, the program makes little use of the system Registry to store configuration information. Most of AutoCAD's configuration data is in numerous configuration files, which you must edit in the program or (worse) using a text editor. Keeping track of and managing this information is time consuming and awkward. A better approach would be to have this information in one place where you can use the NT Registry editor for all configuration needs.

The GUI, the Bad, and the Ugly
As screen 2 shows, the AutoCAD user interface has more toolbars and buttons than any application I've seen. However, AutoCAD R13 for NT is still rooted in the type-a-command method of working. Almost anything you can do from menus, buttons, and dialogs, you can do by typing a command in the ever-present, scrolling command window at the bottom of the AutoCAD screen.

Old-timers who know AutoCAD like the back of their protractors can use the command line to rapidly create a drawing, in much the same way that experienced Windows users know keyboard shortcuts. The difference, however, is that many advanced features are available only from the command line. To a die-hard GUI user, this difference can be something of a culture shock. To make matters worse, the large legacy of commands from previous versions means that many command names are still obscure (although some are amusing, such as the OOPS command, which undoes a previous ERASE command). Forcing you to use the command line for advanced operations makes AutoCAD's learning curve steep. This requirement also makes the overall feel of the program less GUI than I like. After awhile, you realize the toolbars and buttons are just a thin veneer over what is, at heart, a command-line program.

Out of curiosity, I entered a few commands from an old AutoCAD release 2 book. Without exception, they all worked, although R13 contained more options for each command. I can't think of any other software available for the PC that boasts such heritage.

Put to the Test
To see how well AutoCAD performed under various loads on various OSs, I tested AutoCAD using NT 3.51 with Service Pack 3, Win95, and Windows for Workgroups (WFW) 3.11. I ran the tests on my P90 with 40MB of RAM, striped Seagate drives on an Adaptec AHA 2940 SCSI adapter, an S3-based Diamond Stealth 64 VRAM card, and the new AutoCAD WHIP display driver.

As a basic test, I ran AutoCAD and loaded the sample drawing, robot.dwg, that you see in screen 1. I then rendered this drawing using the default rendering settings to produce a reasonably good photorealistic rendering. The performance results are in graph 1.

Not surprisingly, WFW 3.11 finished last and failed to render the complex drawing (robot.dwg) after 7 minutes of disk thrashing. Win95 loaded AutoCAD the fastest, taking just 7 seconds compared to 17 seconds for NT (although NT loaded subsequent instances quicker than Win95). Drawing load times for NT and Win95 were comparable.

Rendering times were always better under NT than Win95 (by about 8% to 12%). The rendering test was highly swap-intensive under both Win95 and NT. As a result, I would have expected Win95's greater available physical RAM to bias the result toward Win95 (which, presumably, with more free RAM, would have had less swapping). The reason NT is faster is probably because of its more efficient disk I/O system, particularly under heavy use, and its more sophisticated page-swap algorithms. This is a significant difference because AutoCAD shops deal with very large drawings that can strain the swapping system of any OS.

Doctor's Orders
NT fans are sometimes disappointed when an NT-specific release of their favorite application is only a straight 32-bit version of a prior 16-bit implementation. This situation is certainly the case with AutoCAD in its present release. However, for AutoCAD, this simple conversion is just what the doctor ordered. The switch from DOS or Windows 3.X to NT as the underlying OS has resulted in a notable performance gain. AutoCAD also benefits from the considerable robustness that NT offers even large applications. I will be interested to see how future versions of AutoCAD, which will probably increasingly use new Win32 features, will continue to push the performance envelope.

AutoCAD is a perfect demonstration of the kind of workstation application NT was designed for. During my tests under NT, I never had the impression that AutoCAD's demands stressed the OS in any way, unlike Windows 3.X and Win95. To build a high-rise building (AutoCAD), you'd better have a strong foundation (NT).