All computer systems work with binary numerical code. There are only two states: voltage (=1) or no voltage (=0)
All arithmetic operations are based on this. In principle, a computer system only adds 0s and 1s together.
The RAM works in the same way. It does not calculate with the values, but it must constantly save them at a very high speed, refresh them and make them available again when required.
The ideal value of maximum electrical voltage for the “1” and absolute absence of voltage for the “0” does not exist in practice. This is why there is the so-called threshold value, which ensures the distinction between “0” and “1”.
With a data bit error, there is the special case that a value “1” is stored by applying a voltage above the fast value in a memory cell. When the value is read out, the voltage content is interpreted as “0” because the voltage has dropped in the meantime or the threshold was not exceeded properly when writing. As a result, the individual bit in the byte is incorrect and an incorrect value is returned by the memory. In notebook or PC systems, this error usually leads to a system crash. In server and workstation memory, the ECC function can detect and correct a simple bit error without interrupting ongoing operation.
It is therefore very important to pay attention to the quality of the RAM. The production of the entire memory as well as the 100% testing of the individual components such as the DRAMs and the memory board (PCB) is essential in order to achieve a failure rate that ideally tends towards zero. Statistically, a data bit error occurs approximately every two years due to external influences such as cosmic radiation (!), without the memory itself being faulty.