256- note sequencer

The sequencer is intended to be used in conjunction with a voltage con-trolled synthesiser. It can store a se-quence of up to 256 notes which can then be played back automatically. The sequence of voltages produced by the keyboard circuit of the syn-thesiser are fed to an 8-bit A/D con-verter and then stored. The length of the note and the length of rests be-tween notes are also encoded with the aid of a clock generator and two counters. When the stored sequence of notes is to be played back, the 8-bit data word corresponding to the keyboard voltage level is read out of the memory and re-converted back into an analogue voltage by a D/A converter. Similarly, the note and rest length data are decoded to ensure that the original melody is obtained.