.DirectX FAQ

What is DirectX?
Why do I need DirectX?
What is the latest version of DirectX?
Where can I get DirectX?
How do I install DirectX?
How do I uninstall DirectX?
How can I check out the inner workings of DirectX?
What is the SDK?
Where can I find out more about DirectX?

What is DirectX?

More and more computers are "customized" these days. There is no way for developers to know exactly what kind of graphics card, sound card, CD-ROM, CD-RW, motherboard, chipset, networking card, memory, etc., is in any given computer. It would be an enormous drain on their time and resources to try and run on every kind of hardware. However, with Microsoft's DirectX, they don't have to worry about it. They write code based on the features of DirectX.

DirectX is an expansion of the Windows operating system, comprised of a runtime module for users and a suite of programming tools for developers. The idea is to allow programmers access to specialized hardware features without having to write hardware-specific code.

For example, bilinear filtering (a very common method of texture mapping, used to make the graphics in most 3D games look more "realistic") is handled differently on ATI, GeForce, and Voodoo graphics cards... not to mention that it's handled differently on the ATI Rage Pro than it is on the ATI Rage 128 or the ATI Radeon, differently on the GeForce2 than on the GeForce 3, and differently on the Voodoo 2 series than the Voodoo 3 series... and that's not covering the permutations within each of those (for example, even though they're using the same basic chipset, the Xpert 128 card doesn't have the broadcast TV and digital video capture functions of the All-In-Wonder 128).

Developerers wanting to use bilinear filtering could write a different version of a game for each graphics card... or they could just write code telling DirectX to handle bilinear filtering. DirectX passes that on to the video card's driver software, the driver sends the instructions to the graphics card, and the card performs the filtering.

Granted, this takes an extra internal step or two longer than writing specifically for the hardware -- which was a big deal in the slow, slow days of the 386, 486, and the earliest Pentiums. Nowadays, with much faster CPUs, busses, and memory, an extra step or two is No Big Deal.

Why do I need DirectX?

You need DirectX because, on a Windows computer, your programs will not run without it. Most modern applications, particularly graphics, multimedia, and games, use DirectX extensively to get the most out of the hardware, and out of the largest range of hardware. Without DirectX on your system, those applications will not even be able to access the hardware -- no sound, no display, no nothin'.

Remember the bad old days, when you never knew if a product would work in your computer until you installed it and tried it? That's just not much of a problem anymore, because hardware standards have improved so much. DirectX is much the same, on the software side. It allows developers and manufacuters to produce the best applications and expansions they can, and makes your configuration of hardware and software, whatever it may be, work smoothly.

Where can I get DirectX?

If you've recently bought a new game or a computer magazine with a coverdisk, chances are excellent you've got DirectX 8 on it. You also can download it from Microsoft's DirectX User Page. The English version, DX80eng.exe, is about 11-1/2 MB; versions for other languages are slightly larger.

How do I install DirectX?

Run the program DX80eng.exe and accept the licensing agreement. The program will need about 50 MB free space on your hard drive to install, but the actual amount of drive space taken up by the final installation will be much smaller, as DX8 will overwrite any previous version. The installation will require you to reboot your computer.

How do I uninstall DirectX?

Actually, you don't. I mean, yes, it is technically possible to remove all of the components of DirectX, but there is no native uninstaller, and frankly I don't recommend you try to do it. DirectX is literally an expansion of your operating system, and most of the programs you run require it.

All that having been said, if you're really interested in how to do it, check out The DirectX Uninstaller WebBoard. and DirectXBuster.

How do I reinstall DirectX?

You might find at one time or another that something seems to have gone wrong with DirectX, or you might not trust that you've got the current version. This usually happens when some badly-written installer, written a few years ago, puts an older version of DirectX on your system.

For example, I've got a really nifty pinball game called Slam Tilt, carried over from the Amiga to the PC, that is absolutely determined that you need DirectX 3. Of course, when I installed this game, I already had DX8, but the installer didn't care, and I found that I had surprisingly little confidence in such a rude program's error checking. So, I reinstalled DirectX.

This is fortunately very easy. Simply Run the program C:\ mssdk \ redist \ directx8a \ dxsetup.exe (assuming, of course, you let DirectX install itself to the default folder) and you'll get the option to Reinstall the latest version of DirectX that's already been installed on your system. You will have to reboot after this, so save your work if you can.

How can I check out the inner workings of DirectX?

Once DirectX is installed, you have access to a powerful utility called DX Diag. (You can Run it from the Start menu; just type in "dxdiag".) This will give you an obscene amount of information about your system and its drivers, and how well your hardware is working. It also provides tests and troubleshooting, so that you can fix system problems on your own.

What is the SDK?

DirectMusic Producer is part of the DirectX Source Developer's Kit, a suite of programming tools used to write software for DirectX. The full suite can be downloaded for free, but it's something like 140 MB. For a nominal fee, Microsoft will send it to you on CD-ROM. For much more information, click here.

Where can I find out more about DirectX?

The primary source for DirectX information is, of course, Microsoft's DirectX Page. The general FAQ for home users is here.

If you're interested in programming, your primary source will be Microsoft's DirectX SDK page. There are many DirectX sites on the Web -- just type "directx" into any search engine -- but be aware that more than a few of them are badly out of date. I'll try to compile a list of the best ones in the near future.

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