PC and DOS Essentials: An Overview

1. An Overview of the PC PC and DOS Essentials

2. The Components of a PC • 1981 - The Key Year • The IBM PC • The Intel 8086 • DOS • All versions of these items have been obsessed with backwards compatibility ever since!

3. WINDOWS DOS HARDWARE The Operating SystemDOS and Windows • DOS, the operating system acts as a link between your PC hardware and your applications • Windows 3.x is a further layer built on top of DOS • Windows 95 is to a large extent independent of DOS

4. Storage Devices • Floppy disks (diskettes) • Slow but convenient • Hold only small amounts of data (1.44 MB) • Hard disks • Fast • Relatively cheap • Hold large amounts of data • Tape drives • Excellent for back-ups • CD-ROMs • Excellent for storing data as reference material • A convenient method for installing programs, such as Microsoft Office

5. The Serial and Parallel Ports • Parallel communication • Faster than serial communication • Used to connect the PC to a printer • Serial communication • Slower, used for connection to a modem

6. The CPU (Central Processing Unit) • The CPU is responsible for all calculations performed within the PC • It determines how fast the PC will run and what systems will run on it • Additionally, it gets involved in a host of other activities, such as overseeing the transfer of data from the hard disk into RAM

7. The ROM-BIOS and the CMOS-RAM • The ROM-BIOS • Read Only Memory - Basic Input Output System • Interface between DOS and the PC hardware • The CMOS-RAM • Complementary Metal Oxide - Random Access Memory • A read/write chip • Stores the system configuration, time and date as well as the power-on password (if you have set one)

8. PC Interrupts • 16 hardware interrupts • Allows items within the PC to signal to the CPU that they require attention • Items must not use the same interrupt line • Use the MSD command to view interrupt usage • When a new card is installed into a PC you must ensure that it does not try to use an interrupt that is already in use

9. DMA (Direct Memory Access) • DMA was introduced in 1981 with the release of the IBM PC • VERY SLOW! • The original PC was based on the Intel 8086 CPU, which at the time was considered an OK sort of chip, running at a reasonable speed • To help out the CPU, the DMA was responsible for moving information from the hard disk or floppy disk into memory, thus by-passing the CPU. This increased throughput and performance

10. Types of Bus Architecture • ISA (Industry Standard Architecture) is the original PC bus architecture, introduced in 1981 • MCA (Microchannel Architecture) was introduced by IBM in 1987 and eliminated many of the ISA design bottlenecks • EISA (Extended Industry Standard Architecture) was introduced in 1989 • Plug and Play is the latest solution and allows automatic hardware configuration

11. ‘Plug and Play’ • Provides a mechanism for automatically configuring any items you add to your PC • Requires three elements to work successfully • The operating system must be Plug and Play aware • Windows 3.1 is not Plug and Play aware, Windows 95 is • The ROM-BIOS must be Plug and Play aware • The cards themselves must be specially designed to be Plug and Play aware

12. Getting HELP Within DOS and Windows • Help in DOS is limited • HELP • command /? • HELP command • Most Windows applications (and Windows itself) contain tutorials, which are very useful for new users • As later versions of applications are released, the Help files are often modified to give improved information concerning tips and tricks • Context-sensitive Help should be invoked when F1 is pressed

13. Directories and Files PC and DOS Essentials

14. What are Directories? • A convenient way of dividing up your hard disk • Each application can be kept in it’s own directory • The root directory is called CD\ • A single . represents the current directory • A double .. represents the parent directory

15. Manipulating Directories Under DOS • Directory commands include: MD CD RD TREE DELTREE Please take care using DELTREE DELTREE

16. Manipulating Directories Using the Windows File Manager • Run the File Manager program, by double clicking on the File Manager program icon, located within the Main group

17. The DIR Command • Switches include: • /w • /p • /s • /?

18. What are Files? • A file is a collection of information contained in a single unit, stored on disk • The DIR command displays a list of files contained in the current directory (the current directory is the directory you are in at the time)

19. File Naming Conventions • There are very strict rules governing the naming of files • A file name can be up to 8 characters, with a 3 character file extension. You cannot use spaces (produced by pressing the spacebar) within a file name • File names, must not contain the following characters:- \ | * ? < > + • You can use the underscore character • This is often useful for making a file name more readable. You can use numbers as well as letters

20. Internal vs External DOS Files • External DOS files are held on the disk, and loaded into your computers memory (RAM) only as and when required • Internal commands are pre-loaded in your computers memory (RAM) when you switch on a DOS-based computer

21. Creating Text Files - EDIT vs COPY CON • COPY CON is a useful technique for creating small text files • Edit is useful for editing existing files or creating large complex text files

22. Renaming, Deleting and Undeleting Files Give me my files back! • DEL • Deletes files • REN • Renames files • UNDELETE • Undeletes deleted files Beware of accidental file deletion!

23. Copying and Moving Files Under DOS • COPY • Internal command • Copies files • XCOPY • External command • More flexible than copy • MOVE • External command • Only works within a disk, not between disks Everything well organized!

24. Copying and Moving Files Using the Windows File Manager • Open the File Manager • Click on the File drop-down menu • Select the Copy or Move command

25. Viewing and Finding Files Within DOS • View with the TYPE command • Use DIR/s to find

26. Viewing and Finding Files Using the Windows File Manager • Open the File Manager • Click on the File drop down menu • Select the Search command • Double click on an associated file to view the file Associated files

27. Manipulating File Attributes • Attributes • Read Only • Archive • System • Hidden • Use of ATTRIB • R Read-only • A Archive • S System • H Hidden • In Windows manipulated via the File Manager • File/Properties

28. Disk Fundamentals PC and DOS Essentials

29. Types - Floppy Disks (Diskettes) and Hard Disks • Hard disks • Non-removable • Inside your PC • Very fast • Hold large amounts of data • Diskettes • Removable • Hold up to 1.44 MB • Very slow

30. Setting Up a Hard Disk From Scratch • Low level formatting • Hard disk supplied with low level formatting • DOS FORMAT command will not low level format a hard disk • Partitioning • With FDISK • High level formatting • Using DOS FORMAT command

31. Disk Partitions • Options include setting up: • A single primary partition • A single extended partition • Multiple logical drives • Manipulated via the DOS command FDISK • A logical drive is anything addressed by a drive letter • If you have a single large primary partition, it is referred to as drive C: • If you have an extended partition, use FDISK to split this into one or more logical drives • Referred to as drive D: E: F: etc.

32. High Level (Logical) Formatting • Also called logical formatting • All logical drives within hard disk partitions must first be formatted • Use the DOS FORMAT command • Only drive C: needs to be a system (bootable) disk

33. Diskette Formatting Considerations • System and non-system diskettes • Quick formatting ? Non-System Disk!

34. Unformatting a Disk • UNFORMAT • When you format a disk, by default it saves information concerning the disks contents • Providing that you use the UNFORMAT command immediately this information can be used to restore the contents of the disk

35. Copying and Labelling Diskettes • DISKCOPY • Uses identical source and target diskettes

36. Speeding Up Disk Access With DEFRAG • Removes file fragmentation • Speeds up disk access • Run DEFRAG if the disk appears slow The effect can sometimes be dramatic

37. Buffers • Used to speed up access from the disk • Set up via the CONFIG.SYS

38. SmartDrive • Setup via the AUTOEXEC.BAT • Can increase to AND from the hard disk

39. Disk Compression DBLSPACE and DRVSPACE • Compresses data held on a disk, and increases the storage capacity • Is it safe? • What about disk performance? After Before

40. Disk Structures • Sides • Sectors • Tracks • Clusters

41. The DOS Boot Sequence • The boot record • Two hidden system files • CONFIG.SYS • COMMAND.COM • AUTOEXEC.BAT

42. RAM Disks • You can treat part of your memory (RAM) as a virtual disk • Accessed much faster than a real disk • Useful with Windows, as you can create temporary files of a virtual disk (by pointing the TEMP= variable to the virtual disk, within the AUTOEXEC.BAT)

43. Memory Fundamentals PC and DOS Essentials

44. Type of Memory Chips - RAM and ROM • RAM • Random Access Memory • Read/write memory • DOS and application programs are loaded into RAM • ROM • Read Only Memory • Contains hard coded information that is used by the operating system • ROM-BIOS • Video ROM • Hard disk ROM

45. The IBM PC, the 8086 CPU and DOS • The original IBM PC containing an Intel 8086 CPU and DOS were all released at the same time • The original PC was designed around the Intel 8086 CPU and DOS in turn was designed to run specifically on the 8086 CPU • DOS has since been left behind by the hardware, including the CPUs It’s not 1981 anymore! DOS

46. Conventional Memory • Defined by addressing limitations of the 8086/8088 CPU • Is the first 1 MB of memory • Not protected • Traditionally only 640 KB used by DOS and DOS applications

47. Extended Memory • Protected Memory above 1 MB • Used by Windows and Windows applications • The original CPU for which DOS was designed only had 20 address lines, and could only address a maximum of 1 MB • In 1984, with the release of the IBM AT based on the Intel 80286 CPU, the number of address lines was raised to 24, giving a maximum memory address range of 16 MB • The first 1 MB was addressed in Real Mode, while the remaining 15 MB were addressed in Protected Mode and were referred to as Extended Memory • 386/486-based PCs can, in theory, address 4 GB of memory • Extended Memory Specification - (XMS) • Defines a standard used to access Extended Memory • DOS and Windows use a driver HIMEM.SYS to control access to the XMS memory

48. Expanded MemoryAn Old Technology! • Used only by certain DOS applications • Windows applications do not require Expanded Memory • Used to extend the life of old 8086-based PCs (which could only address 1 MB of Conventional Memory) • Modern DOS programs will tend to use Extended Memory rather than Expanded Memory • Traditionally requires a special Expanded Memory card and a special device driver • Requires a 64 KB page frame in the UMBs • May now be emulated from Extended Memory by using the EMM386.EXE device driver • DEVICE=C:\DOS\EMM386.EXE

49. 1 MB 640 KB 0 KB The Upper Memory Blocks and the High Memory Area • The UMB space is located between 640 KB and 1 MB • The HMA is a 64 KB area just above 1 MB HMA UMBs Conventional Memory

50. Using the UMBs and HMA - Devicehigh and Loadhigh • Allows you to load items with the CONFIG.SYS and the AUTOEXEC.BAT above the 640 KB limit • CONFIG.SYS • DEVICE=C:\DOS\HIMEM.SYS • DEVICE=C:\DOS\EMM386.EXE • DOS=HIGH,UMB • DEVICEHIGH ..... • AUTOEXEC.BAT • LH .....