Data processor for recording and reading out check data and true data in a cassette tape

A data reader for reading out data in the form of signals contained on a magnetic tape comprising:

• reproduction head means for recalling information stored on said magnetic tape;
• means for initiating the read out of said information;
• control circuit means for variably amplifying said information recalled by said reproduction head means and producing an amplified output;
• volume level detection means receiving said amplified output and determining whether said amplified output has a signal level sufficient for proper readout;
• means for providing an indication of an insufficient signal level in response to a determination by said volume level detection means that said signal level is insufficient;
• data detection means for determining whether said information contained in said amplified output is actual data, said data detection means being operatively connected to said control circuit means only when said amplified output has a signal level sufficient for proper readout as determined by said volume level detection means.