The BBC's television service dates back to 1936 and was originally a nearly live-only medium. The hours of transmission were very limited and the bulk of the programming was transmitted either live from the studio, or from outside broadcast (OB) units; film was a minor contributor to the output. When the first television broadcasts were made, there were two competing systems in use. The EMI electronic system (using 405 lines) competed with the Baird 240-line mechanical television system. Baird adopted an intermediate film technique where the live material was filmed using a standard film camera mounted on a large cabinet which contained a rapid processing unit and an early flying spot scanner to produce the video output for transmission. The pioneer broadcasts were not, however, preserved on this intermediate film as the nitrate (celluloid) stock was scanned while still wet from the fixer bath and never washed to remove the fixer chemicals. Consequently, the film decomposed very soon after transmission; nothing is known to have survived.