The Compact Disc is an excellent medium for professional audio recording. The compact disc stores enormous digital data in a thin metallic foil in the form of microscopic drop lets known as "Pits" which is further covered with thin layers of polycarbonate type plastic at both surfaces. It is rugged, convenient to handle and economical. The disc also provides many additional data recorded under "Sub-code" which is exploited in the CD player to evolve various features for variety of applications. While a low cost CD player for consumer market utilises a part of such information, a professional grade player provides elaborate control on CD transport utilising additional Sub-code information.

The CD20A MK-IV designed by ER&DCI - Thiruvananthapuram, meets all typical requirements of professional grade player provides elaborate control on CD transport utilising additional Sub-code information.