The Old New Thing

Even the publishing department had its own Year 2000 preparedness plan

On December 31, 1999, Microsoft Product Support Services were ready in case something horrible happened as the calendar rolled over into the new year. I'm told that Microsoft Press also had its own Year 2000 plan. They staffed their helpline continuously from Friday evening December 31, 1999 all the way through Sunday, January 2, 2000. They ...

How did that program manage to pin itself to my taskbar when I installed it?

Occasionally, somebody will notice that upon installing a program, it managed to pin itself to the taskbar. But just like there is no Pin­To­Start­Menu function, there is also no Pin­To­Taskbar function, and for the same reason: Because applications would abuse it and auto-pin themselves because they are so awesome, and so...

Integer signum in SSE

The signum function is defined as follows: There are a couple of ways of calculating this in SSE integers. One way is to convert the C idiom The SSE translation of this is mostly straightforward. The quirk is that the SSE comparison functions return −1 to indicate true, whereas C uses +1 to represent true. But this is easy to ...
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Debugging walkthrough: Access violation on nonsense instruction

A colleague of mine asked for help puzzling out a mysterious crash dump which arrived via Windows Error Reporting. Well that's a pretty strange instruction. Especially since it doesn't match up with the source code at all. There is no bit-toggling in the actual code. The method calls to Snap, Crackle, and Pop are all interface calls ...

My pants are fancy!

During the development of Windows, the User Research team tried out an early build of some proposed changes on volunteers from the general community. During one of the tests, they invited the volunteer to just play around with a particular component, to explore it the way they would at home. The usability subject scrolled around a bit, ...

How can I let my child use an app that I bought from the Windows Store?

If you buy an app from the Windows Store, you can make it available to other users on the same Windows PC. This is useful if you, say, buy an app for your child to use. Here's how you do it. (This is all explained on the Windows Store blog, but I've converted it into a step-by-step and updated it for Windows 8.1.) First, sign on as yourself ...

Setting, clearing, and testing a single bit in an SSE register

Today I'm going to set, clear, and test a single bit in an SSE register. Why? On Mondays I don't have to explain why. First, we use the trick from last time that lets us generate constants where all set bits are contiguous, and apply it to the case where we want only one bit. We start by setting all bits in xmm0. We then shift ...
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How did protected-mode 16-bit Windows fix up jumps to functions that got discarded?

Commenter Neil presumes that Windows 286 and later simply fixed up the movable entry table with jmp selector:offset instructions once and for all. It could have, but it went one step further. Recall that the point of the movable entry table is to provide a fixed location that always refers to a specific function, no matter where that ...

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