POST (Power On System Test) indicates errors by a series of pre-defined beeps. It will not make you a cup of coffee if it identifies an error.
keyboard
A 201 error message appears which indicates the RAM failure.
Parity error indicates bad memory. Parity checks compare the memory read with what was writen.
The red underline indicates a spelling error, and the green underline indicates a grammatical error. Note that these programs are not infallible, and it is still up to you to decide if there was really an error.
easy
It places an error message in the BIOS.
POST will indicate error messages by a series of beeps or a series of lighted-up LEDs (depending on your computer).
A typographical error for "post meridiem" meaning afternoon.
Error message on monitor
The #REF! error.
APO indicates either an Army or Air Force post office. FPO indicates a post office used by Navy or Marines.
A stochastic error indicates an error that is random between measurements. Stochastics typically occur through the sum of many random errors.