Straddling two worlds, some DVRs are able to play tapes made on analog VCRs. A few DVRs are also compatible with other digital formats.
All D designations are rack mountable and studio configurable.
Two D1 machines can be teamed up to provide twice the picture detail. D1 and D5 conform to CCIR-601 standard. Same audio tracks and cassette shell as D1, but not compatible with D1. Same signal type as D3 but cassette not compatible. The number 4 means death in Japanese culture, so the manufacturers skipped this number format.