[bmacho]

Here there are more examples: https://en.wikipedia.org/wiki/Acronym#Comparing_a_few_exampl...

Apart from organizations, I'd capitalize only the first character for most.

[croes]

I would capitalize every letter which is pronounced individually.

So it's HIV but Nasa, and because you can hardly pronounce DJGPP it's all capital letters.

[Joker_vD]

The Usa is not an organization.

[itishappy]

That's quite irregular.