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An Overview of the PC

An Overview of the PC. PC and DOS Essentials. 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!. WINDOWS. DOS. HARDWARE. The Operating System DOS and Windows.

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An Overview of the PC

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  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 .....

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