1. Chapter 2 How Hardware and Software Work Together

2. You Will Learn…  How hardware and software interact  How system resources help hardware and software communicate  How an OS relates to BIOS, device drivers, and applications  Different ways an OS can launch applications

3. Hardware and Software Interaction: An Overview

4. Software  The intelligence of the computer  Determines what hardware is present  Decides how it is configured and used  Uses hardware to perform tasks Application software (Office package): does NOT control hardware directly

5. Operating System (OS)  Controls hardware components that make up a computer  Provides an interface for users  Stores, receives and manipulates files  Runs applications

6. Functions of an OS  Uses BIOS  Manages secondary and primary storage  Helps diagnose problems with hardware and software  Interfaces between hardware and software  Performs tasks the user requests

7. Available Operating Systems  DOS  Windows 9x  Windows NT, Windows 2000, and Windows XP  Unix  Linux  OS/2  Mac OS A computer might have several applications installed, but needs only one OS

8. Categories of PC Software  BIOS and device drivers: used to interface with hardware and is installed on hard drive ROM BIOS System BIOS: programs to control I/O devices Startup BIOS: programs to control the startup of a computer CMOS setup: programs to change the setup info stored in CMOS  Operating system  Application software

9. Categories of PC Software

10. System Resources tool used by either hardware or software to communicate with the other READ bottom of page 45

11. System Bus Components Carries data Communicates address (memory & I/O devices) Controls communication

12. ISA Slots Industry Standard Architecture  Used to be the ONLY bus on motherboard  8-bit ISA bus Older bus used on early PCs (1980s) Had eight lines for data  16-bit Provide more memory addresses, DMA channels, and IRQs Still used today 8 bit expansion card can use 16 bit slot—it only uses first part of the slot Modem cards – typically 8 bit

13. 8-Bit ISA Bus can carry either memory addresses or I/O address

14. 16-Bit ISA Bus Read paragraph on page 48 and top of page 49 DEFINE multiplexing

15. Interrupt Request Number (IRQ)  Line on a bus that a device needing service uses to alert the CPU  COM and LPT are preconfigured assignments of system resources that a device can use DEFINE hardware interrupts

16. IRQ Numbers Read page 50

17. Second Interrupt Controller Chip on 16- Bit ISA Bus

18. How IRQs Are Assigned DEMO on front machine

19. Accessing Device Manager to View System Resources DEFINE polling

20. Memory Addresses  Number assignments for memory locations  Hexadecimal numbers, often written in segment:offset form, assigned to RAM and ROM so that the CPU can access both  Example: C800:5, which is 819,205 in decimal DEFINE memory addresses

21. Memory Addresses Appendix C

22. How the CPU Communicates Memory Addresses

23. Division of Memory Under DOS Extended Memory Upper Memory Conventional/Base Memory 0 A0000 FFFFF 100000 Range using Hex 0 640K 1024K Memory addresses DEFINE extended memory

24. Assigning Memory Addresses DEMO on front machine

25. Shadowing ROM  Process of copying programs from ROM to RAM for execution

26. I/O Addresses  Numbers the CPU can use to access hardware devices (much the same way as memory)  Also called port addresses or ports

27. I/O Addresses

28. IRQs and I/O Addresses continued… Handout for students

29. IRQs and I/O Addresses for Devices

30. DMA Channels  Provide a shortcut for a device to send data directly to memory, bypassing the CPU READ page 58 0-3 for slower data transfer 5-7 8-bit ISA can’t access

31. How an OS Relates to Other Software  All interaction between software and hardware is by way of the CPU  CPU operates in two modes: 16-bit (real mode) 32-bit (protected mode)  OS must use same mode the CPU uses Itanium CPU – 64 bit mode

32. Real (16-Bit) and Protected (32-Bit) Operating Modes  Real mode Single-tasking (one application running) 16-bit data path; 1 MB of memory addresses  Protected mode Multitasking (more than one application running) 32-bit data data path; at least 4 GB of memory addresses OS manages access to RAM and does not allow a program direct access to it DEFINE memory extender

33. Real Mode

34. Protected Mode DEFINE virtual memory page/swap file

35. Real Mode and Protected Mode Compared DEFINE preemptive multitasking Handout worksheet

36. How an OS Uses Real and Protected Modes  OS must be in sync with the CPU  Applications must be compiled to run in either real or protected mode  Hybrid of real and protected mode used by older software written for Windows 3.x READ page 61

37. General Types of Software That Run on PCs  16-bit DOS software Designed to run in real mode as only program running and expecting direct access to hardware  16-bit Windows software Designed for Windows 3.x to run where other programs might also be running  32-bit Windows software Designed to run in protected mode with other software and can be loaded into extended memory DEFINE virtual real mode

38. How an OS Uses System BIOS  Contains programming instructions to run simple hardware devices (eg, keyboard and floppy disk drive)  Can be used to access the hard drive OS has choice of using system BIOS or device drivers Device driver is used most often (faster-executes from RAM)  Stored on ROM chips

39. How an OS Uses System BIOS READ paragraph on page 63

40. How an OS Uses System BIOS READ tip on page 64

41. How Device Drivers Control Hardware  Stored on the hard drive  Usually written for a particular OS  Serve same function as BIOS programs

42. Device Drivers 2 kinds: 16 bit real mode 32 bit protected mode Win9x supports both WinNT/2000/XP only supports 32 bit

43. Device Drivers READ bottom page 65 to page 68

44. Windows 9x Device Drivers HANDOUT worksheet

45. Device Drivers under Windows 2000  Uses only 32-bit drivers

46. How an OS Launches Applications  Applications depend on an OS to: Provide access to hardware resources Manage its data in memory and secondary storage Perform many background tasks

47. Loading Application Software Using the Windows Desktop  From the Start menu  Shortcut icon on the desktop  Run dialog box  Windows Explorer or My Computer

48. Using a Shortcut Icon

49. Using the Run Dialog Box to Execute Software

50. Chapter Summary  How operating system software controls several significant hardware devices  How an OS provides the interface that applications need to command and use hardware devices