Roland MTR-100 Wikipedia
The Roland MTR-100 was a digital tape recorder used for storing sequence programmes for the Roland MC-4 Microcomposer. 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.