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Feb 7, 2005
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Why does DS_SHELLFONT = DS_FIXEDSYS | DS_SETFONT?

Raymond Chen

You may have noticed that the numerical value of the flag is equal to . Surely that isn't a coincidence. The value of the flag was chosen so that older operating systems (Windows 95, 98, NT 4) would accept the flag while nevertheless ignoring it. This allowed people to write a single program that got the "Windows 2000" look w...

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Feb 3, 2005
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Why is breadth-first searching better for file system tree walking?

Raymond Chen

Earlier, Eric Lippert discussed one scenario where breadth-first searching is better than depth-first searching. Today, I'll tell you about another. If you go back to the old MS-DOS file enumeration functions, you'll find that there is a "Find first file" function and a "Find next file" function, but no "Find close" function. That's because the ...

History
Feb 2, 2005
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The history of the Windows PowerToys

Raymond Chen

During the development of Windows 95, as with the development of any project, the people working on the project write side programs to test the features they are adding or to prototype a feature. After Windows 95 shipped, some of those programs were collected into the first edition of the Windows 95 Power Toys. As I recall, the fir...

History
Jan 18, 2005
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The importance of error code backwards compatibility

Raymond Chen

I remember a bug report that came on in an old MS-DOS program (from a company that is still in business so don't ask me to identify them) that attempted to open the file "". That's the file with no name. This returned error 2 (file not found). But the program didn't check the error code and though that 2 was the file handle. It then began writi...

History
Jan 17, 2005
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How did MS-DOS report error codes?

Raymond Chen

The old MS-DOS function calls (ah, int 21h), typically indicated error by returning with carry set and putting the error code in the AX register. These error codes will look awfully familiar today: They are the same error codes that Windows uses. All the small-valued error codes like ERROR_FILE_NOT_FOUND go back to MS-DOS (and possibly even furth...

History
Jan 11, 2005
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Why doesn't \ autocomplete to all the computers on the network?

Raymond Chen

Wes Haggard wishes that \ would autocomplete to all the computers on the network. [Link fixed 10am.] An early beta of Windows 95 actually did something similar to this, showing all the computers on the network when you opened the Network Neighborhood folder. And the feature was quickly killed. Why? Corporations with large networks wer...

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Jan 11, 2005
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Why doesn’t \ autocomplete to all the computers on the network?

Raymond Chen

Wes Haggard wishes that \ would autocomplete to all the computers on the network. [Link fixed 10am.] An early beta of Windows 95 actually did something similar to this, showing all the computers on the network when you opened the Network Neighborhood folder. And the feature was quickly killed. Why? Corporations with large networks wer...

History
Dec 20, 2004
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Don’t save anything you can recalculate

Raymond Chen

Nowadays, a major barrier to performance for many classes of programs is paging. We saw earlier this year that paging can kill a server. Today, another example of how performance became tied to paging. The principle is "Don't save anything you can recalculate." This of course, seems counterintuitive: Shouldn't you save the answer so you don't h...

History