How do P.O.S.T. cards work?

[jacatone]

I've been reading about P.O.S.T. cards. Do the codes they reveal work for all manufacturers, or are they different for each one? Thanks.

 

[onadal]

I've been reading about P.O.S.T. cards. Do the codes they reveal work for all manufacturers, or are they different for each one? Thanks.

Most of the POST cards works in same way.
They show you NOT THE PROBLEM but you can see some codes.
These codes are last step of POST in a motherboard
If u have a 4 digits Postcard, the first 2 codes is the code where is stuck, and the 2 others is the last step that worked good.
So I´ve been looking on internet for some sites where you can learn how to detect a really electronic problem on mainboards, but there´s nothing.... you can only ask in some forum about your problem but it´s probably no one answer.