In 1986, a SCSI-equipped LaserDisc player attached to a BBC Master computer was used for the BBC Domesday Project. The player was referred as an LV-ROM (LaserVision Read Only Memory) as the discs contained the driving software as well as the video frames. The discs used the CAV format, and encoded data as a binary signal represented by the analog audio recording. These discs could contain in each CAV frame video/audio or video/binary data, but not both. "Data" frames would appear blank when played as video. It was typical for each disc to start with the disc catalog (a few blank frames) then the video introduction before the rest of the data. Because the format (based on the ADFS hard disc format) used a starting sector for each file, the data layout effectively skipped over any video frames. If all 54,000 frames are used for data storage an LV-ROM disc can contain 324 MB of data per side. The Domesday Project systems also included a genlock, allowing video frames, clips and audio to be mixed with graphics originated from the BBC Master; this was used to great effect for displaying high resolution photographs and maps, which could then be zoomed into.