 Classic Forth systems traditionally use neither operating system nor file system . Instead of storing code in files , source code is stored in disk blocks written to physical disk addresses . The word BLOCK is employed to translate the number of a 1K @-@ sized block of disk space into the address of a buffer containing the data , which is managed automatically by the Forth system . Block use has become rare since the mid @-@ 1990s . In a hosted system those blocks too are allocated in a normal file in any case . 
