Saturday, January 24, 2004
A twisty passage of Windows, all fragile
The
HLTinstruction tells the CPU to shut itself down until the next hardware interrupt. This is a big win on laptops since it reduces power consumption and thereby saves your lap from third-degree burns.We (well, specifically, Jeff) had this implemented and working in Windows 95 but discovered to our dismay that there were many laptops (some from a major manufacturer) which would lock up unrecoverably if you issued a
HLTinstruction.So we had to back it out.
Then the aftermarket
HLTprograms came out and people wrote, “Stupid Microsoft. Why did they leave this feature out of Windows.” I had to sit quietly while people accused Microsoft of being stupid and/or lazy and/or selfish.
Hardw are Backwards compatibility
From Mark come a pointer to Raymond Chen's weblog, a developer from Microsoft. An amazing insight into Microsoft development, covering why they did what they did, and >why they do what they do.
Even if you aren't a developer for Microsoft Windows, it's still facinating reading, such as this little bit:
CreateMenu creates a horizontal menu bar, suitable for attaching to a top-level window. This is the sort of menu that says “File, Edit”, and so on.
CreatePopupMenu creates a vertical popup menu, suitable for use as a submenu of another menu (either a horizontal menu bar or another popup menu) or as the root of a context menu.
If you get the two confused, you can get strange menu behavior. Windows on rare occasions detects that you confused the two converts as appropriate, but I wouldn't count on Windows successfully reading your mind.
What' s the difference between CreateMenu and CreatePopupMenu?
From reading Raymond's blog, it seems that Microsoft goes to great lengths to protect mediocre programmers and keep their programs running; their backwards compatibility legacy is quite impressive (I can still run an editor written in 1982 under MS-DOS 1.0 on Windows XP, some twenty-two years later). With so much legacy code (MS-DOS versions 1.0 (1981) through 7.x (1995) and Windows 1.0 (1985) through Windows XP) it's no wonder Windows is such a mess, much less that it still runs.
