 It was offered as an optional accessory for faster data transfer than a standard audio cassette player.When using a Roland MTR-100, the Roland MC-4 Microcomposer needed to be fitted with the additional memory option known as the OM-4.The MTR-100 used digital computer cassettes, Roland endorsed the use of TEAC Computer Tape CT-300 or Maxell Data Cassette Tape CT-300 or M-90.