The DVD Dilemma

By Jerry Pournelle

March 8, 2004

(The DVD Dilemma :  Page 1 of 1 )

Column 283 (Continued from the Previous Week)

64-Bit Windows In Our Time?

From 8-bit CP/M to 32-bit Windows, history is clear: When larger address spaces support larger applications, larger applications will be written to take advantage of them. However, this trend moves fastest when the larger address space is flat, requiring no segment registers or other tricks. Few wrote code specifically for the 286.

I believe this trend will continue for programs into the 64-bit era. Very few will write code for this 36-bit mode of Windows on Pentiums. Using the IMAGE_FILE_LARGE_ADDRESS_AWARE flag, and all the other hacks surrounding it, is too much like work. In practical terms, mass-market applications which support more than 2 GB of RAM are going to wait until 64-bit Windows for AMD ships, and then for a demand to appear. Even if applications could take advantage of 4 GB of RAM before AMD64, very few programmers will bother. Few are currently bothering to properly support even 1 GB of RAM, at least in our tests.

Now, note: There are Itanium-specific versions of some apps. At the 2003 WinHEC in New Orleans, H-P demonstrated an Itanium-native geo-mapping application which directly addressed 12 GB of RAM. But workstation use of Itanium hasn't left the lab, and I doubt it will. If the Itanium has a market on Windows, it's for servers.

The 2003 Microsoft Professional Developer's Conference (PDC) introduced a great lot of new concepts, programming models, and a roadmap for Longhorn, the replacement for Windows XP due sometime in the next 24-36 months. Microsoft did not, however, announce any real plan for 64-bit migration, not in the clever sort of way Apple did for 68K to PowerMac transition. Plans were specifically vague on the Windows for AMD64 ship date (probably mid-2004), and that will also slow any innovation based on 64-bit Windows.

Until and unless it's dead simple to build applications which can directly address more than 2 GB of RAM, very few new types of apps will be built to take advantage of extra RAM.

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