Windows Extended Codes: 0128 to 0255
This is Windows’s own extended character set, code page 1252, everything from Alt+0128 to Alt+0255. It replaced part of the older DOS table when Windows 3.1 shipped, trading some DOS line-drawing and card-suit glyphs for currency signs, accented letters and typographic punctuation more useful in a graphical operating system.
The leading zero marks a code as belonging to this set rather than the older DOS one.
Questions
Why do these codes always start with a zero?
The leading zero tells Windows to read the number against code page 1252 instead of the original DOS code page 437.
Does Alt+0128 to Alt+0255 work in every Windows application?
Most do, though some older or specialised software still expects the DOS code page instead, in which case the character will not match.
What replaced the DOS symbols in this range?
Mostly accented letters, currency signs and typographic punctuation, prioritised for word processing and web use over the original line-drawing and card-suit glyphs.
Is code page 1252 the same across every version of Windows?
Yes, for the range this page covers. Code page 1252 has been Windows’s default Western European character set since Windows 3.1 and has not changed since.
Why do some older web pages show a black diamond with a question mark instead of these characters?
That symbol appears when a browser cannot match a byte to a character in the encoding it assumes, usually because a page was saved in one character set and served as another.