D-1 or 4:2:2 Component Digital is an SMPTE digital recording video standard, introduced in 1986 through efforts by SMPTE engineering committees. It started as a Sony and Bosch - BTS product and was the first major professional digital video format. SMPTE standardized the format within ITU-R 601 (orig. CCIR-601), also known as Rec. 601, which was derived from SMPTE 125M and EBU 3246-E standards. Format D-1 or 4:2:2 D-1 (1986) was a major feat in real time, broadcast quality digital video recording. It stores uncompressed digitized component video, encoded at Y'CbCr 4:2:2 using the CCIR 601 raster format with 8 bits, along with PCM audio tracks as well as timecode on a 3/4 inch (19 mm) videocassette tape (though not to be confused with the ubiquitous 3/4-inch U-Matic/U-Matic SP cassette). The uncompressed component video used enormous bandwidth for its time: 173 Mbit/sec (bit rate). The maximum record time on a D-1 tape is 94 minutes. Because of the uncompromising picture quality - component processing and uncompressed recording, D-1 was most popular in high-end graphic and animation production - where multiple layering had previously been done in short run times via hard drives (Quantel Harry, Henry, Harriet, Hal or Abekas DDR) or via multiple analog machines running at once. Hard drives in the 1980s that stored broadcast-quality video would typically only hold 30 seconds to a few minutes of space, yet the systems that made them work could cost $500,000. By contrast, the D-1 machine allowed 94 minutes of recording on a $200 cassette. D-1 resolution is 720 (horizontal) × 486 (vertical) for NTSC systems and 720 × 576 for PAL systems; these resolutions come from Rec. 601. A small variation removing the top 6 lines to save space was later introduced and made popular in the 1/4-inch DV/DVCAM/DVCPro formats and for digital broadcasting, which have 720 x 480 pixels for NTSC; and is also used in DVD-Video and Standard-definition television. The D1 units are switchable between NTSC and PAL. Luma is sampled at 13.5 MHz and Chroma at 6.75 MHz with an overall data rate of 27 MHz. Sampling at 13.5 MHz was used as it is a common multiple of NTSC/PAL line rate (6x 2.5 MHz). The first input/output interface was a 25 pin parallel cable (SMPTE 125M) and later updated to serial digital interface on coaxial cable (SDI, SMPTE 259M, 75Ω coax, 270 MHz). Ancillary data can be