Introduction/purpose Readers of this Report should be aware that the text in this Report is the original text generated during the development of the SDTV digital interfaces. It is has been retained as an historic record of the digital interface development. Many of the concepts and technical parameters developed during the 1982 to 1986 time-frame have changed@ readers are advised to consult the latest ITU-R Recommendations before implementing digital interfaces. Reference is made to the International Radio Consultative Committee (CCIR)@ the year 1920 saw the beginning of sound broadcasting at the improvised studios of the Marconi Company@ and in 1927@ the CCIR was established at a conference held in Washington D.C. The International Telephone Consultative Committee (CCIF@ set up in 1924)@ the International Telegraph Consultative Committee (CCIT@ set up in 1925) and the CCIR were made responsible for coordinating the technical studies@ tests and measurements being carried out in the various fields of telecommunications@ as well as for drawing up international standards. In 1989 the CCIR was reorganized into the International Telecommunication Union (ITU)@ over time@ the Union was streamlined into three Sectors@ corresponding to its three main areas of activity: Telecommunication Standardization (ITU-T)@ Radiocommunication (ITU-R) and Telecommunication Development (ITU-D). Today the ITU-R has the responsibility for broadcasting services. The broadcasting and related industries depend 100% on the interfaces and their derivatives that were proposed back pre-1986. In 1986 in Houston Texas the first digital serial interface as we know it today was demonstrated at a trade show@ since that time the serial interface which originally ran at 270 Mbit/s (an interim interface ran at 243 Mbit/s@ this interface had only very limited use) has been extended to 3 Gbit/s. The serial interface has also been adapted to carry almost any data signal in addition to the uncompressed video signals that was the original intent. Further treatment of the characteristics of the serial interfaces as implement can be found in EBU Tech. 3283. The following text is presented as an historic record of the digital interface development@ along with a copy of the original Recommendations CCIR 601 and 656. The original Recommendation CCIR 656 was never implemented on a widespread basis as it was constrained to 8-bit operation. A later version@ Recommendation ITU-R BT.656-2 replaced the 8/9 code mapping with scrambled NRZ coding. It is the scrambled NRZ version of the serial digital interface that found very widespread implementation. The original Recommendation CCIR 601 was originally called CCIR-AA/11 and was approved in 1982. The attached Recommendation CCIR 601-1 has been restored using the original text along with any errors that may have been in this text.