File address
13 3-byte addresses (39 bytes)
Direct :10 : direct pointer 10 1K chunks of memory
Single indirect: 1 : indirect block of 256 points each of which points to a 1K : 256 K
Double indirect: 1: 256 X 256 : 65M
Triple Indirect : 1: 256X 256 X 256 : 16G