tailieunhanh - Lecture Operating system concepts - Lecture 21

After studying this chapter, you should be able to: Assess the key security issues that relate to operating systems, understand the design issues for file system security, distinguish among various types of intruder behavior patterns and understand the types of intrusion techniques used to breach computer security, compare and contrast two methods of access control. | CSC 322 Operating Systems Concepts Lecture - 23: by Ahmed Mumtaz Mustehsan Special Thanks To: Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. (Chapter-5) Silberschatz, Galvin and Gagne 2002, Operating System Concepts, Ahmed Mumtaz Mustehsan, CIIT, Islamabad 1 Chapter 5 Input/ Output Lecture-23 Ahmed Mumtaz Mustehsan, CIIT, Islamabad 2 OS controls I/O devices => Issue commands, handles interrupts, handles errors Provide easy to use interface to devices Hopefully device independent First look at hardware, then software Emphasize software Software structured in layers Look at disks Overview Lecture-23 Ahmed Mumtaz Mustehsan, CIIT, Islamabad 3 Some typical device network, and bus data rates. I/O Devices Lecture-23 Ahmed Mumtaz Mustehsan, CIIT, Islamabad 4 Two types of I/O devices- block, character Block Can read blocks independently of one another Hard disks, CD-ROMs, USB sticks 512 to 32,768 bytes Character Accepts stream of characters without block structure . | CSC 322 Operating Systems Concepts Lecture - 23: by Ahmed Mumtaz Mustehsan Special Thanks To: Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. (Chapter-5) Silberschatz, Galvin and Gagne 2002, Operating System Concepts, Ahmed Mumtaz Mustehsan, CIIT, Islamabad 1 Chapter 5 Input/ Output Lecture-23 Ahmed Mumtaz Mustehsan, CIIT, Islamabad 2 OS controls I/O devices => Issue commands, handles interrupts, handles errors Provide easy to use interface to devices Hopefully device independent First look at hardware, then software Emphasize software Software structured in layers Look at disks Overview Lecture-23 Ahmed Mumtaz Mustehsan, CIIT, Islamabad 3 Some typical device network, and bus data rates. I/O Devices Lecture-23 Ahmed Mumtaz Mustehsan, CIIT, Islamabad 4 Two types of I/O devices- block, character Block Can read blocks independently of one another Hard disks, CD-ROMs, USB sticks 512 to 32,768 bytes Character Accepts stream of characters without block structure Printers, mice, network interfaces Not everything fits, . clocks don’t fit Division allows for OS to deal with devices in device independent manner File system deals with blocks Overview Lecture-23 Ahmed Mumtaz Mustehsan, CIIT, Islamabad 5 A is track, B is sector, C is geometrical sector, D is cluster Disk geometry Lecture-23 Ahmed Mumtaz Mustehsan, CIIT, Islamabad 6 I/O unit has 2 components-mechanical, electronic (controller) Controller is a chip with a connector which plugs into cables to device sometimes more than one of identical devices like SCSI controllers can handle 8 drives including (CD drive) Disk Disk might have 10,000 sectors of 512 bytes per track or different spec. Serial bit stream comes off drive Has preamble 4096 bits/sector, error correcting code Preamble has sector number, cylinder number, sector size . Device Controllers Lecture-23 Ahmed Mumtaz Mustehsan, CIIT, Islamabad 7 Controller assembles block from bit stream, does error correction, puts into buffer in .