The presenter would then use the machine to find out about a particular topic. The name "chock-a-block" was derived from the machine's ability to read data from "blocks" - which were just that, physical blocks painted different colours. A typical show would include dialogue from the presenter, a brief clip played on Chock-a-block's video screen, and the presenter recording a song on Chock-a-block's audio recorder (which resembled the reel-to-reel tape drives used on actual mainframes, but with a design below to cause the reels to resemble the eyes of a smiling face).
According to the Kaleidoscope 'Lost Shows' database, eight out of thirteen episodes are no longer in the BBC archives.
The story of Chockablock :http://www.thechestnut.com/chockablock.htm