The Old New Thing

How are window manager handles determined in 16-bit Windows and Windows 95?

July 16, 2007 Jul 16, 2007 07/16/07

Raymond Chen

(Prefatory remark: The following information is of the "behind the scenes" nature and does not constitute formal documentation. Actually, nothing I write counts as formal documentation, so I shouldn't have needed to write that, but people sometimes intentionally play stupid and interpret all forms of the future tense as if I were making some ...

Choosing a provocative debug signature

June 4, 2007 Jun 4, 2007 06/4/07

Raymond Chen

Back in Windows 95, there was an elusive heap corruption bug in the graphics engine, and after a lot of analysis, the graphics folks were convinced that the corruption was coming from outside their component, and they had a pretty good idea who the corruptor was, but they needed proof. One of the standard techniques of narrowing down the...

Why do operating system files still adhere to the old 8.3 naming convention?

April 2, 2007 Apr 2, 2007 04/2/07

Raymond Chen

Commenter Brian Reiter asks a duplicate of a question that was already submitted to the Suggestion Box: Darren asks why operating system† files still (for the most part) adhere to the old 8.3 naming convention. There are a few reasons I can think of. I'm not saying that these are the reasons; I'm just brainstorming. First, of ...

What is a SM_SLOWMACHINE?

March 12, 2007 Mar 12, 2007 03/12/07

Raymond Chen

Jason Doucette asks how slow a machine has to be to be considered a . The answer: Pretty darned slow by today's standards. When the metric was introduced in Windows 95, the definition of a "slow machine" was as follows (roughly): That bit about the display driver is a little strange. Windows actually trusted display drivers to ...

What was the first parameter to CoInitialize used for?

March 6, 2007 Mar 6, 2007 03/6/07

Raymond Chen

Larry Osterman explains in a two-part series, The sad story of CoGetMalloc and Why was the ability to specify an allocator during CoInitialize removed from the system...

Why can't you set the command prompt's current directory to a UNC?

February 15, 2007 Feb 15, 2007 02/15/07

Raymond Chen

If you try to set the current directory of a command prompt, you get the error message "CMD does not support UNC paths as current directories." What's going on here? It's MS-DOS backwards compatibility. If the current directory were a UNC, there wouldn't be anything to return to MS-DOS programs when they call function 19h (Get current drive...

Why doesn't the window manager unregister window classes when the owning DLL unloads?

February 12, 2007 Feb 12, 2007 02/12/07

Raymond Chen

If you look at the documentation for the function, you'll see that it calls out different behavior depending on whether you're running Windows 95 or Windows NT. Commenter Vipin asked why Windows NT doesn't follow Windows 95's lead. Back in the old days, 16-bit Windows did unregister classes automatically when a DLL ...

Why did Explorer say "The target you specified is on the desktop"?

February 5, 2007 Feb 5, 2007 02/5/07

Raymond Chen

In Windows 95, if you had a shortcut to a file on the desktop, view the shortcut's properties, and then clicked "Find Target", you got the message "The target you specified is on the desktop". It also selected the item on the desktop to help you find it. But why didn't it just open an Explorer window that viewed the desktop? Because in ...

Unusual uses for a ball-point pen: Breaking into the debugger

January 30, 2007 Jan 30, 2007 01/30/07

Raymond Chen

Ah, the ISA bus...

Where did the Windows Vista wallpaper images come from?

January 25, 2007 Jan 25, 2007 01/25/07

Raymond Chen

Windows Vista needed some new wallpapers. Where to get them? Historically, they were purchased from a professional service, which is expensive since Microsoft would need worldwide rights to reproduce (not just use) the image, and not just for a few months, but for decades. Besides, there are a lot of good amateur photographers at Microsoft who...