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By Martin Heller
Although the Nashville (Microsoft's code-name for the browser-enabled shell) updates give Windows a whole new look, it's only on the surface-the underlying plumbing is basically unchanged. That's not to say the plumbing needs work. In fact, the plumbing is very good.
he Win95 (and NT 4.0) Explorer is little more than a container for some standard controls. The left pane is a tree view control that displays the system folder hierarchy; the right pane is a list view control that displays the current folder's contents in any of four formats. At the top of the right pane is a column header control; above and below both panes are status bar controls; and below the outer frame menu is a toolbar control.
The big cosmetic change in Nashville is actually a very small change in the Explorer. In addition to a list view control, the right-hand pane can also be an HTML browser control, referred to as a page view. The page view control is called the IExplorer Browser. IExplorer Browser is an OLE (or ActiveX) document object container that holds MsHtml. This document object implements Web, ftp and gopher browsing. If you've been running Internet Explorer 3.0, you're already familiar with IExplorer Browser and MsHtml. All IE3's tiny IEXPLORE.EXE does is act as a container for IExplorer Browser.
Don't underestimate the power of this little Explorer change. The new page view also works on the Web. Every folder in your system can have a customized display format, using the same HTML code you'd use to design a Web page. The HTML pages can contain scripts, Windows controls, and ActiveX controls and document objects. It isn't far-fetched to imagine developing whole integrated applications based on browsing a directory hierarchy in page view, especially since many major programs (Word, for instance) are already document objects.
Having Explorer as the container for your Web browser provides another advantage. You'll recall the left-hand pane in Explorer is a tree view control. What better way to display the hierarchy of a server? It's natural to display ftp and gopher servers as trees, because the information to do so is already on these servers. With a small enhancement-a map file in the top directory of a site-you can also display Web sites as trees. If you've ever wandered aimlessly around a Web site looking for a page you just know is there, crying as you wait for the graphics on each page to display, you'll appreciate the elegance of navigating the entire site as easily as you navigate the directories on your own hard disk.
Technically, Nashville represents a small Windows evolution; socially, it lays the groundwork for a revolution in Windows development.
Parts of the Nashville extensions work in both NT 4.0 and Win95, because they hook into the shell, which is the same in both systems. Other parts have to be customized to each system, because they need to use the underlying plumbing, and that's different in the two systems.
Several issues have to be addressed before the two can evolve into a single structure-which we'll call Windows 2000. One issue is Unicode; another is virtual device drivers; and a third is kernel device drivers.
Unicode is a way of representing all the international character sets in a single 16-bit numbering system. NT uses Unicode characters internally; Win95 uses the more familiar 8-bit ASCII characters internally. At some point, Win95 will have to support Unicode-probably in Memphis (the version of Win95 after Nashville), which is scheduled for release in 1997 or 1998.
Virtual device drivers (VxDs) are one of the cornerstones of the Win95 architecture, but NT doesn't support them. This is one reason NT can't run many Windows 3.1x and 95 applications. Although Microsoft tells us it won't add VxD support to Cairo (the version of NT after NT 4.0), such decisions are often reversed for technical or marketing reasons.
Another difference in NT and Win95 is the device driver model. For historical reasons, NT device drivers are not exactly the same as those in Win95. Vendors that want to market Windows printers, video cards and other peripherals need to write separate device drivers for the two systems. Often, NT support lags Win95 support by several months.
Both Cairo and Memphis will support a new, merged device driver model, known as the Windows driver model (WDM). Support for WDM drivers should be in addition to support for existing drivers on both systems, but again, such decisions are often reversed.
In the Windows 2000 time frame, we hope WDM will be in such widespread use that support for legacy drivers can be dropped. Windows 2000 will probably come in three flavors--Desktop (corresponding to Win95), Workstation (NT Workstation) and Server (NT Server). But all three will share a single architecture and kernel based on the NT kernel, and a single set of device drivers based on WDM.
Of course, by then CPU power should have doubled at least twice to about 1,000MIPS, and most people will connect to the Internet at 10 times today's data rates using cable modems. It'll be a different world, in which the computer will be more an appliance than a tinkerer's obsession, and the system software will have become more robust, forgiving and easy to use.
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