2. A system according to claim 1, wherein said storage means comprises a recording medium having at least one recording track and means for recording data in said blocks along said track of the medium and wherein said indicating means comprises a table block for each track, means for recording in each table block information indicating that a block of the corresponding track is free for storing code data therein and reading means for reading the information in the table block to effect a search for a block free for storing code data therein.
3. A system according to claim 2, wherein said control means further comprises means for controlling the storage means to store the free status of each block sequentially in order of address into said table block, manually manipulatable means for controlling said storage means to effect movement of the medium and to enable said reading means to sequentially read the information in each table block, means responsive to the sequential reading of the table block for identifying the address of the first encountered free block, a first storage register, means for recording the identified address in said first storage register, and comparison means for comparing the identified address with the addresses of the sequentially read blocks during further movement of the medium and for generating a command signal when the read address compares with the address stored in said first register.