Why does [ALT+224] return Ó instead of alpha?

As you have already discovered, the characters resulting from character codes between 0 and 255 depend entirely on the encoding that is used.

Windows doesn't use neither extended ASCII nor ANSI (usually Windows-1252); it actually depends on the application.

For example, Alt + (2, 2, 4) gives on my machine:

• α in Notepad and on the command prompt.

• à in Google Chrome's omnibox, but α in its console and this very text area.

• In Notepad++, a with ANSI, α with UTF-8.

For a more consistent behavior, just use Unicode character codes:

The key combination Alt + (9, 4, 5) – or Alt + (+, 3, B, 1) if you set the registry key HKEY_CURRENT_USER\Control Panel\Input Method\EnableHexNumpad to 1 – should result in a α in every application that supports that character.

Sadly, that isn't the case:

• The decimal char code results in ▒ in IE's address bar, while the hexadecimal one just beeps.

• The decimal char code results in ▒ in Notepad++ with ANSI and ¦ with UTF-8.

• The hexadecimal char code results in a in Notepad++ with ANSI and α with UTF-8.

Summary

1. Set HKEY_CURRENT_USER\Control Panel\Input Method\EnableHexNumpad to 1.

2. Use Alt + (9, 4, 5) or Alt + (+, 3, B, 1) in applications with full Unicode support.

3. Fall back to trial and error in applications that lack full Unicode support.

I found a solution that worked for me.

Initially, the "Current language for non-Unicode programs" was set to "English (United Kingdom)" on the computer in Region → Administrative settings; however, when I changed it to "English (United States)" and restarted the computer.

I finally started to get "α" when I hit Alt 224. No more "Ó". I've attached an image of the settings location.