with a fixed 5 v reference available from the dash 16 analog digital input card 50 to give a 5 v 0 05 v precision reference voltage output alternatively an external d c or a c reference may be used to give different output ranges typically the dash 16 analog digital input card 50 is double buffered to provide instantaneous single step update the digital input output from the input card 50 comprises of 4 bits of ttl dtl or cmos compatible digital output and 4 bits of digital input as shown in fig2 the analog digital input card 50 is incorporated within a modified personal computer 52 which can be of an ibm pc or xt type sufficient to interface with the dash 16 analog digital input card 50 the numbers parameters and commercial brand names just given are exemplary and not absolute and may be substituted by analog to digital converters known in the art of signal processing next the digital signals resulting from the dash 16 analog digital input card 50 are further analyzed to determine if certain analog bioelectric frequencies 44 are being generated by the player 22 a selector means 30 allows sufficient manipulation of the digital signals so as to separate particular digital signals which correspond to the particular bioelectric analog frequencies to be used in changing the sequence of visual images this function can also be achieved by using.