Operating Systems Principles of 1/0 Hardware e Block device u Stores information in fixed -size blocks. each one with its own address I The essential property of a block device is that it is possible to read or write each block independently of all the other ones H Disks g Character device Delivers or accepts a stream of characters, without regard to any block structure w It is not addressable and does not have any seek operation t Printers. network interfaces. mouse Other device A cloc k Gao Haichang, Software School, Xidian UniversityOperating Systems Gao Haichang , Software School, Xidian University 5 Principles of I/O Hardware  Block device  Stores information in fixed-size blocks, each one with its own address.  The essential property of a block device is that it is possible to read or write each block independently of all the other ones.  Disks  Character device  Delivers or accepts a stream of characters, without regard to any block structure.  It is not addressable and does not have any seek operation.  Printers, network interfaces, mouse  Other device  clock