Showing results for August 2004 - The Old New Thing

In an earlier article, I gave an example of reading a contract from the other side. Here's another example of how you can read a specification and play the role of the operating system. I chose this particular example because somebody wanted to do this and didn't realize that everything they needed was already documented; they just needed to look...

It has become obvious by now that the mobile phone has changed the way people interact. These two papers were forwaded to me by a colleague, whose summary I am shamelessly lifting from heavily. First is a short paper titled Exploring the implications for social identity of the new sociology of the mobile phone. The much more fascinating (and ...

The various Interlocked functions (InterlockedIncrement, and so on) require that the variable being updated be properly aligned, even on x86, a platform where the CPU silently fixes unaligned memory access invisibly. If you pass an unaligned pointer to one of the Interlocked functions, the operation will still succeed, but the result won't be ato...

Sometimes unaligned memory access will hang the machine. Some video cards do not let you access all the video memory at one go. Instead, you are given a window into which you can select which subset of video memory ("bank") you want to see. For example, the EGA video card had 256K of memory, split into four 64K banks. If you wanted to access memo...

Some Windows structures are variable-sized, beginning with a fixed header, followed by a variable-sized array. When these structures are declared, they often declare an array of size 1 where the variable-sized array should be. For example: typedef struct _TOKEN_GROUPS { DWORD GroupCount; SID_AND_ATTRIBUTES Groups[ANYSIZE_ARRAY]; } TOKEN...

The FILETIME structure represents a 64-bit value in two parts: typedef struct _FILETIME { DWORD dwLowDateTime; DWORD dwHighDateTime; } FILETIME, *PFILETIME; You may be tempted to take the entire FILETIME structure and access it directly as if it were an __int64. After all, its memory layout exactly matches that of a 64-bit (little-endian)...

Even though a value is stored in the registry as REG_SZ, this doesn't mean that the value actually ends with a proper null terminator. At the bottom, the registry is just a hierarchically-organized name/value database. And you can lie and get away with it. Lots of people lie about their registry data. You'll find lots of things that should be...

Ten thousand human beings in peak physical condition. All in one dormitory complex. With 130,000 free condoms. Let the games begin! And you have to tip your hat (tam?) to The Scotsman for finding an athlete named "Randy Jones" for this article.

It was designed when computers were a lot slower.

A table of contents now that the whole thing is over. I hope. I'm not sure how successful this series has been, though, for it appears that even people who have read the articles continue to confuse virtual address space with physical address space. (Or maybe this person is merely mocking a faulty argument? I can't tell for sure.)