Introduction to PC's
Introduction to PC's
Manchester Computer Centre
November 1991 First Edition
Preface
Acknowledgement: The sections relating to MS-DOS have been extracted fro m documentation produced by the Oxford University Computer Centre and are included by permission and with gratitude.
- Introduction
- 2. The Components of a PC
- 3. Classifying PCs
- 4. Floppy Disks
- 4.1. Sizes and Capacities
- 4.2. Use of Floppy Disks
- 4.3. Handling Floppy Disks
- 4.4. Problems With Floppy Disks
- 5. Hard Disks
- 5.1. Partitioning a Hard Disk
- 5.2. Problems With Hard Disks
- 5.3. Backing Up the Hard Disk
- 5.4. Disk Caching
- 6. Video Displays
- 7. System Memory
- 8. Printers and Plotters
- 9. Maths Co-processors
- 10. Expansion Slots
- 11. Mice, Digitizers, and Scanners
- 12. The Keyboard
- 13. What Is MS-DOS?
- 14. The Start Up Procedure
- 15. MS-DOS and Disks
- 16. Files and Filenames
- 16.1. Files
- 16.2. Filenames
- 16.3. File Extensions
- 16.4. File Specifications
- 16.5. Wildcard Characters
- 16.6. Directories
- 17. MS-DOS Commands
- 17.1. Listing the Contents of a Directory
- 17.2. Displaying and Printing the Contents of a File
- 17.3. Copying Files From One Disk to Another
- 17.4. Renaming Files
- 17.5. Deleting Files
- 17.6. Programs
- 18. Controlling the Screen
- 18.1. Clearing the Screen
- 18.2. Stopping the Screen from Scrolling
- 18.3. Abandoning Commands
- 18.4. Command Line Editing
- 19. Ending a Session on the PC
- 20. More About Directories
- 21. Directory Commands
- 21.1. Creating a Directory
- 21.2. Changing the Default Directory
- 21.3. Deleting a Directory
- 21.4. Listing the Contents of a Directory
- 21.5. Copying Files from One Directory to Another
- 21.6. The TREE Command
- 21.7. The PATH Command
- 22. Batch Files
- 23. Further MS-DOS
- 24. Application Programs
- 25. Networking
- Glossary of Terms
- 2. The Components of a PC
This guide is an introduction to Personal Computers or PCs. The term PC
covers IBM PCs and compatible microcomputers or clones. The guide is in two
parts. The first part covers hardware aspects of PCs, the second covers the
use of the PC. Also included is a glossary explaining common terms and
acronyms.
A PC is a microcomputer. A PC is a single-user system, designed to fit on a
desk-top; hence the word Personal. The IBM PC was introduced in the early
eighties and since then has been modified and improved. Subsequent PCs have
been designed to run any software written for previous versions of the PC.
Many other manufacturers have produced compatible computers; that is,
computers which work in the same manner as the IBM PC and use the same
software. These are often known as clones.
The next section explains the various components that make up a PC.
Part A - PC Hardware
A PC consists of a main unit (or system box), monitor, keyboard and
peripherals (see figure 1). Peripherals include devices such as printers and
the mouse.
Figure 1 Components of a PC
The main unit contains the Central Processing Unit (CPU) and various
supporting Integrated Circuits (or chips) all of which are fixed to a
printed circuit board (PCB) called the motherboard. The main unit also
houses disk drives, expansion slots and the power supply.
The CPU (Central Processing Unit) or processor is the `brain' of any computer
system. In the PC it is contained on a single Integrated Circuit or `chip'.
The CPU processes all instructions and data.
The CPU is driven by an internal clock. Simply speaking, every time the clock
pulses the CPU processes one instruction. Thus, the faster the clock the
quicker the CPU processes its instructions. Clock speed is measured in
MegaHertz (MHz).
Most PCs will have a button on the front panel labelled `turbo'. This allows
you to switch the clock speed of the processor. In the past certain programs
tripped over themselves when the processor was running at high speed, hence the
inclusion of a turbo switch to allow the processor to run at a lower speed.
Nowadays, however, this is a rare problem.
All PCs are fitted with a certain amount of workspace memory called Random
Access Memory (RAM). This memory is used for storing running software and
data which the software requires, as well as the operating system.
The contents of RAM are lost when the PC is switched off. For example,
if you are running word processing software then the software and the document
you are working on are stored in RAM. To save the document, after making any
changes you wish to keep, it is necessary to copy the document from RAM onto
disk.
RAM is located in chips situated on the motherboard. Most PCs come with 1
Megabyte of RAM as standard. However, not all of this is directly useable (see
later).
Disk drives provide a means of storing work, or data. Floppy disks are
transportable from PC to PC and come in two sizes, 31/2" and 51/4" diameter.
Hard disks are fixed inside the system unit and have much higher storage
capacities than floppies. Disk drives are discussed in sections 4 and 5.
Information is stored on disk in the form of files. A file might be a
program or data such as a word processor document. Files can be grouped
together on disk in directories.
Located at the rear of the PC are various sockets or ports. These allow the
keyboard and monitor to be connected. Most PCs include a parallel port
(usually used for printers) and two serial ports (usually used for
communications with other computer systems or connecting mice and plotters).
Also included inside the system box are expansion slots. These allow
extra hardware to be added to the PC using printed circuit boards, or
cards, plugged into the expansion slots. The slots are connected to the
CPU via the bus. The bus is a set of wires which transfers data. Think
of it as a motorway.
The monitor provides display output from the PC. Monitors vary in screen
resolution and colours available. See section 6 for more information.
The keyboard allows you to input commands and information into the PC. The
keyboard is normally connected to the main unit via a 5 pin DIN type socket.
See section 12 for more information.
As well as the essential keyboard and monitor, peripheral items such as
printers and mice are often found connected to PCs. These are covered in later
sections.
An essential part of any computer is its operating system. An operating
system is a program which provides the links between the computer hardware, the
user, and software which is running on the computer system and controls all the
components of the computer, including its peripherals. PC-DOS, Personal
Computer Disk Operating System, is the operating system used on IBM PCs. Most
PC compatibles, however, use the more widely available MS-DOS, MicroSoft-Disk
Operating System. MS-DOS and PC-DOS are virtually the same. The use of MS-DOS
is covered in Part B.
The first IBM PC was introduced in the early eighties and since then there
have been many changes in the technology used by PCs and new models are
introduced regularly.
PCs can be loosely grouped as follows, in order of time of introduction, PC
XT, PC AT (or 286), 386, 386SX and 486.
The main change from version to version is in the type of processor (CPU)
used. CPUs have increased in complexity and speed.(see table 1). Table 1 Types of PC and Their Processors
Notes:
1. The 8088 is a slower version of the 8086.
2. The 80386SX was introduced after the 80386 and is a cut down version of the
80386 and is thus slower but cheaper. Since the introduction of the 80386SX
the 80386 is now often referred to as the 80386DX.
3. Strictly speaking 386, 386SX and 486 machines are AT type PCs, since the
change from XT to AT was more than a change in processor. The 80286 based
PC-AT is now often referred to as a 286.
4. Once the manufacturing techniques used for a particular processor have been
refined, faster versions of a processor can be produced, hence the range in
speeds for a processor. Also, owing to a improvement in manufacturing
techniques in general, processor speeds as a whole are increasing.
It should be noted that processor speed is not all - buying a PC with twice
the clock speed will not double your rate of working; other factors such as
disk access times are important.
Software designed to run on an XT should also run on any other type of PC but
the reverse is not always the case.
As well as differences in the processor used, PCs also vary in their physical
shape and size. Most PCs are of the desktop type shown in figure 1. PCs are
also available in portable versions. Portable PCs have the main unit, screen
and keyboard all combined in one unit and some can be run from batteries as
well as from mains supply. With the introduction of low power ICs and disk
drives and the improvements in screen technology, portable PCs are becoming a
popular choice.
A notebook PC is a smaller version of the portable PC and is usually A4 in
size. Tower PCs are similar to desktop PCs except they are placed end on and
rest on the floor.
Floppy disks provide a means of storing work. You can write
information onto the disk and read information from the disk. Floppy
disks are used by inserting them into a disk drive.
A light on the disk drive indicates when the disk is being accessed.
Removing or inserting a disk while the drive light is illuminated may cause
damage to the disk and is likely to result in the loss of data stored on the
disk.
Figure 2 Tracks and sectors
Before a disk can be used it has to be formatted for use by MS-DOS.
Formatting writes the tracks and sectors onto the disk's surfaces
(see figure 2). A common combination is nine sectors and 40 tracks.
Formatting a disk destroys any information currently contained on the disk.
Floppy disks are normally double sided i.e. information is written on both
sides of the disk. Formatting is covered in section 15.1.
Floppy disks come in two sizes, 31/2" and 51/4". Each size has two different
capacities (see table 2).
Table 2 Floppy Disk Capacities
Double density disks are also known as low density, and high density
disks as high capacity.
Disk drives exist for each of the four disk capacities. Usually XT PCs can
only be fitted with double density drives (i.e. 360Kb, 51/4" drives and 720Kb,
31/2" drives), whereas all other PCs are fitted with high density disk
drives.
31/2" floppies, as well as having higher capacities, are also more robust and
compact and are to be recommended. More and more software is being released on
31/2" disks. PCs tend to come with a combination of one 51/4" drive and one
31/2" drive or a single 51/4" or 31/2" drive.
Disk drives are referenced by their drive letter. If your system has a
single floppy disk drive, it will be referred to as drive A. A
second floppy disk drive will be referred to as drive B. Hard disk
drives are referenced from letter C onwards.
Obviously 31/2" floppy disks cannot be used in 51/4" drives and vice versa but
it also must be noted that while high density drives can read double density
disks, double density drives cannot read high density disks.
For example a 51/4" disk formatted to 1.2Mb on an AT cannot be read by a 360Kb
XT floppy disk drive. See section 15.1 on formatting disks.
Figure 3 Write Protection
Floppy disks can be write protected. This prevents any information
from being written to or deleted from the disk and prevents the disk from being
formatted. On 51/4" disks this is done by folding a sticky tab over the write
protect slot; on 31/2" disks by sliding a plastic tab into the open position
(see figure 3).
If handled carefully, both 31/2" and 51/4" floppy disks are reasonably robust
and can be used repeatedly without any problems. Disks may eventually reach the
point when they should be discarded but this will normally be a few years.
There are however a number of very important `dos and don'ts' relating to the
handling of the less robust 51/4" floppy disks. DO:
Protect disks from becoming dusty or scratched by replacing them in their
envelopes as soon as they are removed from a disk drive;
Hold disks by the edges or corners only;
Use only felt-tip pens to write on disk labels that are already stuck onto
disks (or, preferably, write the labels before sticking them onto
disks);
Keep them in a plastic library case.
DON'T:
Bend floppy disks;
Insert or remove a disk while a disk drive light is on;
Use pencils, ballpoint pens or any other `sharp' writing implements to write
on disk labels that are stuck onto disks;
Touch the exposed recording surfaces of disks;
Leave disks in full sunlight or any other places where they are liable to
become too hot;
Stand anything (manuals, books, coffee mugs etc.) on disks;
Leave disks near magnetic fields such as telephones, dictation equipment,
Hi-fi speakers, photocopiers, laser printers or anything containing an electric
motor (including the PC).
A floppy disk which has previously been working without problems becomes
unreadable. Floppy disks are liable to wear and tear. If you have trouble
reading information from a disk, for example you may have a bad sector
error, do not despair, there are utility programs such as those from Norton
which can in some cases recover data from a disk with problems.
A floppy disks works perfectly well in one PC but fails to work in
another. Check that both PCs have the same type of drives. i.e. you are
not trying to read a high capacity disk in a low capacity drive.
Your floppy disk does not fit into the disk drive. You are trying to use
a 51/4" disk in a 31/2" disk drive.
Hard disks (or fixed disks) work on the same principle as floppy disks but are
fixed inside the PC in a sealed unit. They can store a great deal more
information than floppy disks and range in capacity from 10Mb to several
hundred Mb. Access times (i.e. the time taken to read and write information)
for hard disks are much faster than for floppy disks. Manufacturers often
quote access times as well as capacities for hard disks.
A lot of application software requires that you have a PC with a hard
disk and it is to be recommended.
Hard disks can be split into different logical drives by partitioning.
For example a 60Mb hard disk can be partitioned into two 30Mb logical disks,
which can be treated as two separate drives, C and D.
Under MS-DOS (versions less than 4) the maximum size of the primary hard disk
is 32Mb therefore drives of a size greater than this have to be partitioned
(unless the hard disk comes with a special disk manager program). Partitioning
can also be a way of splitting up the disk into more manageable sizes.
Most PC suppliers partition and format hard disks before distribution.
Hard disks are contained in an air-sealed unit and are thus less liable to
physical problems than floppies. However the consequences of any disk failure
are much higher than for floppies so some form of backup must be carried out
regularly.
All hard disks will have a number of bad sectors which will be marked as bad
when formatting. The disk drive will not then write any information onto these
sectors. Using the CHKDSK command (see section 15.3) regularly will
inform you of whether the number of bad sectors is increasing. If this is the
case then you may be having problems.
Viruses affect can affect all your files whether on hard or floppy disks. A
virus is a computer program that replicates itself by attaching to files. Some
viruses can be relatively harmless, simply filling up the hard disk; others may
destroy all the files on the hard disk.
Software is available which will scan through disks searching for infected
files and repairing them if possible. It must be noted, however, that these
programs can only cope with viruses of which they are aware.
Owing to the much higher capacities of hard disks, backing up is much more
time consuming. Backing up a whole 110Mb hard disk onto floppies is not really
feasible.
A possible solution is to make selective backups i.e. only back up your work
files or files which have changed since the last backup. MS-DOS comes with a
backup program which facilitates backups.
A more expensive solution is to use a tape streamer which backs up the
hard disk on to a tape. A 20Mb disk can be backed up onto a cartridge tape in
less than 5 minutes.
Tape streamers can be installed into the PC, usually into a slot in the front
of the PC. External, self-contained, tape streamers are available which can be
shared by any number of PCs.
Transferring data to and from the hard disk can be relatively time consuming,
compared with the speed at which data is transferred in and out of memory and
to and from the CPU.
Disk transfers can be reduced by using a disk cache. A cache is an
area of memory where data commonly transferred to and from the hard disk is
stored. If the data required from the disk is currently in cache then that
data is called from the cache rather than from disk. Since transferring data
to and from memory is a lot quicker than to and from disk, time is saved.
Disk caching is especially useful in disk intensive applications.
The original IBM PC was only able to display text and in monochrome only.
There are now various display options available on PCs, some offering high
resolution colour graphics. The display quality is dependent on the video card
in the PC. The display is driven by a set of ICs called the video
adapter or display adapter. This circuitry is contained on a PCB, a
video card, which normally takes up one of the expansion slots, allowing the
graphics display to be upgraded by replacing the card (and in some cases
changing the monitor).
The resolution of a PC's graphics display is defined by the number of
pixels, or dots, produced on the screen. The more pixels that make up an image
the clearer the image will appear.
There have been several graphics standards introduced over the years which
vary in resolution, colours available and cost.
The Hercules standard has high resolution monochrome graphics with a
resolution of 720 by 348 pixels. It is still a popular option due to its low
cost.
CGA was the first colour graphics option available on the PC. It has 16
colours available, but due to its poor resolution it is not a popular choice
and is not widely available now.
The EGA has high resolution (640 by 350) 16 colour graphics and is a vast
improvement on CGA.
VGA offers higher resolution (640 by 480) and more colours (256) than EGA.
Owing to reduction in cost it has made the EGA virtually redundant and is
currently the standard display option on most new PCs.
There are other, non-standard, display adapters available that provide higher
resolution and more colours than the VGA standard. These include the 8514A
adapter, which has a resolution of 1024 by 768 and up to 256 colours, and
Super-VGA. Super-VGA, although not standard, has been adopted by many
manufacturers as an improvement on the standard VGA display. IBM has recently
announced XGA, intended as the successor to VGA. It must be noted that, as
with other graphics adapters, the software you are running must be capable of
driving the display adapters to get the full benefit of higher
resolution and more colours.
As mentioned earlier, the video output from the PC is usually incorporated on
an expansion card slotted into the PC. This makes it possible to upgrade the
graphics on a PC with ease. It must be noted, however, that the monitor must
be capable of accepting the signals from the graphics card.
A lot of software is designed to run on a particular graphics standard. It is
necessary, therefore, to check that the PC has the necessary graphics card in
order to run the particular package.
Most graphics adapters are downward compatible; for example a VGA card can
emulate CGA graphics.
Monitors are available in colour and monochrome versions and in different
screen sizes.
It is necessary to have the correct monitor connected to the PC. For example
a PC fitted with a VGA card will not work with a monitor designed for CGA
graphics.
Multisynch monitors are capable of working with several different graphics
adapters and at several different resolutions.
Most PCs come with 1Mb of system memory (RAM) as standard. However the
operating system, MS-DOS, is limited to using only 640Kb of memory.
Figure 4 Memory map of PC
The map of a PC's memory is shown in figure 4. As stated earlier, the
operating system, MS-DOS, limits the amount of memory for user programs and
applications to 640Kb. This is due to the limitations of the original PC's
processor. When the PC was first introduced 640Kb of memory was perfectly
adequate, but since then faster and improved processors have been developed,
capable of addressing more memory, and the 640Kb limit has become a limiting
factor on the development of PCs. Many methods have been tried to find a way
around the memory limit to allow larger programs to be run.
The original CPU on the PC, the 8086, is only capable of addressing, or
accessing, up to 1Mb (1024Kb) of memory. The top 384Kb of this was set aside
for system use, such as the graphics memory, leaving 640Kb for use by the
user's programs (in fact the available area will be less than 640Kb, since
MS-DOS itself takes up some of this memory). Subsequent processors such as the
80286 are able to address more memory (e.g. 16Mb for the 286) but MS-DOS is
unable to access this extra memory.
Early efforts to get round the memory limitations were based on the use of
expanded memory. Under the expanded memory method extra memory is
paged into the area between 640Kb and 1Mb when required, thus making it
accessible by the CPU. Up to 32Mb of RAM can be accessed in this way. It must
be noted that the application software must have been written to take advantage
of expanded memory. The standard specification for expanded memory is the LIM
(Lotus-Intel-Microsoft) EMS (Expanded Memory Specification).
Expanded memory is usually available in the form of plug in cards (see section
10).
Extended memory is a contiguous block of memory from 1Mb upwards.
Extended memory is only available to 80286 processors and above. It cannot,
however, be accessed directly by MS-DOS programs but various techniques can be
used to make it available for programs. For example Windows 3 and some
versions of Lotus 123 can use it and extended memory can also be
configured to appear like expanded memory. In all cases the software
application needs to have been specially written to take advantage.
Memory caching works on the same principle as disk caching. The rate of data
transfer to and from system memory is limited by the speed of the RAM chips
used. Unfortunately high speed memory chips cost more than lower speed memory
chips. To increase the rate of data transfer to and from the CPU and the RAM a
cache of high speed memory is used. The cache controller works out which block
of memory is the most commonly used and transfers its contents into the
cache.
The 80486 processor has an in-built memory cache. Some of the more expensive
80386 based PCs come with cache memory and controllers.
A RAM disk is a block of system memory which is made to appear like an extra
disk drive. Since transferring data to and from memory is much faster than
transferring data to and from disk, RAM drives are very fast. RAM drives are
normally located in the area between 640Kb and 1Mb. Note that the contents of
a RAM drive is lost when the PC is switched off.
Virtual memory can be regarded as the inverse of RAM disks. With virtual
memory hard disk space is made to appear like system memory, thus increasing
the amount of memory available for programs. This technique is used by
Windows 3.
As stated earlier not all of the base 640Kb memory is available to the user,
since part of it is taken up by MS-
DOS
and device drivers. (A device driver is a piece of software which
allows the PC to communicate with or `drive' a particular hardware device such
as a mouse).
The latest version of MS-DOS, version 5.0, has a feature allowing some of this
memory area to be freed by allowing most of the operating system and device
drivers to be loaded in some of the unused area between 640Kb and 1Mb. Thus
more memory is free for application programs.
A printer may be connected to one of the serial or, more commonly, parallel
ports of a PC. The availability of a printer is especially important for
applications such as word processing. Printers vary enormously in quality and
speed of output.
Printers can be grouped by the method with which they print.
The most common type of printers are dot-matrix. This refers to the way ink
is applied to the paper - by a set of pins impacting onto the paper through an
inked ribbon to form each character. Printer quality depends on the number of
pins on the printer head. This is usually 9 pins, but 24 pin printers are
available with a corresponding increase in print quality (and cost).
Most dot-matrix printers have NLQ (Near Letter Quality) options where higher
quality output is produced at a lower print speed.
The standard for dot-matrix printers is Epson and virtually all
dot-matrix printers claim Epson compatibility.
Daisywheel printers were the first printers to produce letter quality (LQ)
output; their operation being similar to that of typewriters. They are limited
by the fact that they can only produce characters that exist on the daisywheel
and cannot produce graphical output, only text.
Daisywheel printers have been made virtually obsolete by the wide availability
of cheap laser printers and inkjet printers.
Laser printers have the advantage of being able to produce letter quality text
as well as high quality graphics. Their disadvantage is that they are
expensive to buy and run; although costs are coming down.
Laser printer quality is measured in dots per inch, the most common being 300
dpi. They are page printers, fan fold paper cannot be used; but one (or
sometimes two) automatic paper feed trays are an integral part. Printing speed
is usually quoted in pages per minute (ppm).
Laser printers tend to have a larger range of fonts than other
printers. A font is a set of characters in a particular typeface. For example
this document has been producing using Times Roman with section headings in
Helvetica.
The Hewlett Packard Laserjet series is a fairly common standard, many laser
printers emulating it.
The printer's in-built memory can usually be increased to allow the use of
downloadable (or soft) fonts. These are fonts which are stored on disk
and transferred to the printer's memory when required.
Some laser printers (e.g. Hewlett Packard) use font cartridges which can be
plugged into the printer to increase the number of fonts available.
Postscript Printers are a type of laser printer offering more flexibility,
in terms of fonts and font sizes, than normal laser printers. They are,
however, considerably more expensive. Postscript is a page description
language rather than a hardware standard.
Inkjet printers work by spraying a fine jet of ink on the paper to form the
characters or graphic. Inkjet printers produce high quality output, near to
that produced by laser printers, and are quiet in operation. Examples include
the Hewlett Packard DeskJet.
Printers are connected via a port at the back of the PC. This is usually the
parallel output port (25 pin female) although a few printers use the serial
interface. Serial interfaces are considerably slower.
A printer can be shared between a number of PCs using a switching box (either
manual or automatic).
It is advisable to switch on the printer (and any other peripherals) before
switching on the PC.
Make sure that the printer you intend using is supported by your software
package. Most software packages, on installation, provide a list of printer
models from which to choose. If your particular printer is not catered for
select an Epson printer if you have a dot-matrix; or a Laserjet printer if you
have a laser printer.
A pen plotter is an output device essential for graphical applications like
Computer Aided Design (CAD). Plotters provide a better quality graphics output
than printers and allow the use of different colours (high quality colour
printers are available, but very expensive).
Your application package will translate your graphic into plotter
instructions. The Hewlett Packard Graphic Language (HPGL) provides the
standard for output to plotters, and the majority of plotters will accept HPGL
output.
Plotters can be interfaced to a PC by a parallel or serial link (although
serial connection is more common than for printers, since the parallel port is
usually taken up by any printer attached).
Plotters come in various configurations, varying in number of pens available
(usually 4 or 8; one for each colour) and size (A4,A3 etc).
Common manufacturers include Hewlett Packard and Roland.
A Maths Co-processor (or Floating Point Unit, FPU) is an optional chip that
can speed up the execution of your software considerably. Floating point
operations such as decimals and logarithms can take many instruction steps on
the main processor. Such calculations can be handled more efficiently if
passed on to a co-processor.
Therefore, if your software requires many maths calculations (e.g.
Spreadsheets, CAD) the installation of a co-processor will be advantageous and
in some cases a necessity. The increase in speed can be as much as a factor of
five. On the other hand some applications such as word-processing will benefit
little or not at all from the installation of a co-processor.
Co-processors can be included as an option on purchase of a PC or installed at
a later date. The slot for the co-processor resides on the motherboard, close
to the CPU. Installation is a straightforward process.
It is important to note that application software needs to have been written
with a co-processor in mind, otherwise there will be no advantage at all in
having a maths co-processor installed. Most software written for use with
co-processors will check whether one is installed.
Some software packages will not work, or will run very slowly, unless a
co-processor is installed.
Co-processors have to be matched to the main processor. They are numbered in
a similar manner to main processors (see table 3). The clock speed of the
co-processor also has to be matched with that of the main processor (the
exception is the 80287 co-processor which need not match the main processor in
speed). For example, a PC with a 20MHz 80386 processor will require a 80387
co-processor running at a speed of 20Mhz. Table 3 Selecting the Correct Co-processor
Note that the 80486 processor has an in-built maths co-processor.
To allow extra features to be added, most PCs have expansion slots.
These slots allow the insertion of expansion cards. Data is transferred
to and from expansion cards via electronic tracks called the bus.
The bus is analogous to a motorway - the more tracks on a bus the faster data
can be transferred. For example, a bus 32 tracks (lanes) wide can carry twice
as much data as a bus 16 tracks wide. A bus 16 tracks wide is known as a 16
bit bus i.e. 16 bits of data can be carried down the bus simultaneously. The
number and width of slots vary from PC to PC. To save space some PCs will have
fewer expansion slots, thus allowing a smaller system box.
Usually the disk controller (the circuitry which controls the disk drives),
graphics adapter and serial and parallel ports are located on cards, thus
reducing the number of slots available for other purposes. Common uses for
expansion slots are networking cards (e.g. Ethernet), digital/analogue
converters and FAX cards. Expansion cards also allow extra RAM to be added to
the PC.
Putting graphics adapters and disk controllers on cards allows the PC to be
easily modified and upgraded.
As mentioned earlier data is transferred to and from cards via the system bus.
There are four main types of bus, varying in width and speed of data
transfer.
The original PC bus (found on XT machines) is only eight data bits
wide, so data can be transferred in blocks of eight bits.
The AT bus, which was introduced with the AT PC, is sixteen bits wide
and operates at a higher speed than the PC bus. Thus data transfer rates are
much higher. The AT bus is also found on 386 PCs and remains the most
common.
The Micro Channel Architecture (MCA) bus was introduced by IBM in their
PS/2 PCs. It is 32 bits wide and faster than the AT bus, as well as having
other features. Few PCs have an MCA bus. It is incompatible with previous
buses and MCA cards will not work in other systems.
The Extended Industry Standard Architecture (EISA) bus is, like MCA, a
32 bit bus but is compatible with existing AT expansion cards. Currently few
PCs have an EISA bus.
The majority of PCs have a mixture of 16 bit and 8 bit expansion slots.
This section covers alternatives to the keyboard for inputting information and
instructions to the PC.
A mouse is a device which moves a pointer around the screen, options being
selected by pressing (or `clicking') a mouse button.
More and more software is being written incorporating menus. An option on a
menu being selected by moving the mouse cursor over the option and clicking on
it. With some software such as CAD a mouse is essential. Graphical User
Interfaces, such as Windows and GEM, in practice also require the use of a
mouse.
A mouse is normally linked to a PC via the mouse port. The standard for the
mouse is the Microsoft Bus Mouse. Another common type of mouse is the serial
mouse which connects to one of the serial ports in the PC. Normally software
called a mouse driver has to be loaded into memory before the mouse can
be used. Generally mice have two buttons but three button mice are also
available. If you have software which requires the third, centre, button to be
pressed, this can be achieved by pressing both buttons simultaneously.
A digitizer (or graphics tablet) is an input device, used in Computer Aided
Design for reading a paper drawing into a CAD package; in effect by tracing the
drawing. As well as digitizing drawings, digitizers can be used as a
replacement for a mouse. Digitizers come in sizes from A4 to A0 size.
Scanners allow you to convert an image on paper into a bitmap file.
The image can then be displayed on the PC and used in applications such as Desk
Top Publishing. It is also possible to run Optical Character Recognition
software in conjunction with a scanner and read in printed text into the PC.
For example an abstract can be scanned and imported into a word processor for
further manipulation. Scanners can be either flatbed or hand-held.
This section covers the use of the keyboard.
There are two styles of keyboard in common use, the older 84-key and the now
more common 102-key expanded keyboard. The 102-key keyboard normally consists
of four main parts;
A typewriter-style alphanumeric keyboard with four extra keys labelled Esc
(Escape), Ctrl (Control), and Alt (Alternate).
A numeric keypad, situated at the far right of the keyboard, providing the
digits 0 to 9, a decimal point and plus and minus signs, together with four
special keys labelled Num Lock (Number Lock), Scroll Lock, Ins
(Insert) and Del (Delete). On the 84-key keyboard the numeric keys
are also used as cursor control keys.
In between the alphabetic keys and the numeric keypad there are two groups of
keys. The top group repeats the functions on the numeric keypad. Below there
are four cursor keys. These are not present on the 84-key keyboard.
A set of twelve function keys situated in a single row above the main
typewriter keyboard and labelled F1 to F12. On the 84-key keyboards there are
ten function keys situated to the left of the main typewriter keys.
The layout of these keys is shown in figure 6 and their general uses are
described in the following sections. The position of some of the keys may be
different from that described below.
In order to save space, the keyboards on portable and notebooks PCs have
largely different layouts from that described above.
Figure 5 102 Key Keyboard Layout
As with a typewriter, to type upper case (capital) letters, or to obtain a
punctuation mark or symbol shown on the upper half of a key, hold down one or
other of the two <Shift> keys while pressing the key marked with the
required character.
The Shift keys are normally situated on each side of the bottom line of letter
keys and are often marked with a `fat' up-arrow). To type text in capital
letters, the keyboard can be `locked' into capitals by pressing the
Caps-Lock key (the key or a sign on the keyboard may be lit).
Since Caps Lock only affects the letter keys, it will still be
necessary to hold down a Shift key to obtain the punctuation marks and
symbols shown on the upper half of keys. To return to lowercase letters, press
the Caps-Lock key again (the light will go out). If you press
Shift while Caps-Lock is engaged you will revert to
lowercase i.e. Shift always reverses the current state of
Caps-Lock.
The numeric keypad at the right of the keyboard can be used for numeric input
only if the Num Lock key is pressed (the key or a sign on the
keyboard may be lit). To release the numeric keypad and hence use the cursor
keys (labelled with arrows), press the Num Lock key again; the
light will go out.
On some keyboards the cursor keys are also a separate group of four keys (see
figure 6). Either set of cursor keys may be used.
As well as the four cursor control keys, keys marked PgDn (Page Down),
PgUp (Page Up), Home and End are available for cursor
movement, depending on the software being used. These keys are also duplicated
on the numeric keypad.
The key on the right-hand side of the alphanumeric keyboard that is often
L-shaped and larger than the other keys, and is labelled with a right-angled,
left-pointing arrow ([[??]]) and/or Return or Enter (see figure
6), is used to send a command line to the computer to be processed. After
typing in a command to the PC, this key must be pressed to enter or
start the command. In general, commands may be entered in upper or lower case
letters, or a mixture of the two.
The <Return> key is sometimes known as the <Enter> key. There is
also an <Enter> key on the numeric keypad which can be used in exactly
the same way as the <Return> key.
To correct a mistake that you notice before you have pressed the
<Return> key, use the <Backspace> key to `erase' the mistake. The
<Backspace> key is situated above the <Return> key and is labelled
with a left-pointing arrow.
Each time the <Backspace> key is pressed, the character to the left of
the current cursor position is deleted. (The cursor is the flashing underline
displayed on the screen.) The correct characters can then be retyped before
pressing the <Return> key.
The Insert key, sometimes marked INS, acts as a toggle key when
entering data or commands. In insert mode any characters entered push into the
current line at the cursor position. In overstrike mode any characters entered
will overwrite any characters currently displayed.
The operation of the Function Keys depends on the particular software
being used. For example pressing F1 on a lot of software packages calls up a
help screen.
The ESC key usually allows you to `escape' from a particular
environment.
The Print Screen key, sometimes marked PrtSc, when pressed in
conjunction with the Shift key copies the screen image to the printer.
The Alt and Control keys are used in combination with other keys
to execute particular commands depending on the software being used. For
example Control-F2 will initiate a spell check when using WordPerfect.
Part B - Using the PC
MS-DOS stands for MicroSoft Disk Operating System.
MS-DOS is the software underlying a series of commands that will allow
programs to be run, files holding information to be created and managed, and
disks to be written to and read from. MS-DOS is loaded from a disk, known as a
system disk, when the PC is switched on.
It is important to appreciate from the start, and in particular when using
MS-DOS from a floppy disk, that there are two types of MS-DOS commands,
internal (or resident) and external (or transient).
Internal commands are loaded and held in the computer's memory when MS-DOS
is started up and can thus be executed immediately when required even if the
system disk is no longer available. Examples of internal commands are: COPY,
DEL, DIR, REN and TYPE. Internal commands are held in a file called
COMMAND.COM.
External commands are not loaded into the computer's memory when MS-DOS is
started up and are read from the disk only when required. This means that a
command of this type will fail on a floppy disk system unless the MS-DOS system
disk is in the current disk drive at the time that the command is issued;
otherwise the appropriate drive name and path should precede the command name
(see section 20.1).
If an MS-DOS disk is not available or the path to the MS-
DOS
directory has not been specified when a external command is issued, there will
be an error message of the form,
Bad command or filename
Examples of external commands are: DISKCOPY, FORMAT and PRINT.
Note: In the following sections,
(1) Characters typed by you are in ITALIC CAPITALS
(2) Text displayed on the PC screen is in bold
(3) Keys to press are enclosed by < > e.g. <F2>
(4) <Control/Z> means hold down Control key and press Z
(5) Return and Enter are one and the same. Every command entered should be
followed by a Return key press.
Start up, or boot up as it is often called, is the process of readying
the hardware and software for use. The disk with the MS-DOS system files on it
is often referred to as a bootable disk since this disk can be used to
start up the system. The term `booting' the system comes from the saying
`pulling oneself up by one's bootstraps'.
Startup is performed each time the computer is switched on. The startup
procedure copies the internal operating system commands into the PC's memory,
where they will remain until the system is restarted or switched off. Startup
has been successful when the system prompt (the disk drive name) is displayed
on the screen.
To start up MS-DOS on a PC with a hard disk take the following steps;
(l) Check that there is no floppy disk in the floppy disk drive.
(2) If the display screen is not already on (check the light which is normally
below the screen), turn it on. Also turn on any peripherals such as
printers.
Turn the PC on. Nothing will appear to happen for a few seconds while the PC
performs a `self check' of its internal components, such as system memory, and
reports any problems. It does this whenever it is first turned on.
The light on the front of drive C, the hard disk, will come on and the drive
motor will start running as the internal part of MS-DOS is read into the
computer's memory.
(3) Once the internal portion of MS-DOS has been loaded, the system may prompt
on the screen for today's date. The prompt takes the following form,
Current date is Tue 01-06-1991
Enter new date (dd-mm-yy):
Pressing <Return> will leave the date unchanged. Alternatively enter
the new date in the form mm-dd-yy (i.e. month-day-year, two digits for
each e.g. 08:12:90) or it may be in the form dd-mm-yy, check the format
before entering the correct date. After typing in the date, press the
<Return> key.
(4) The current time may then be requested. The prompt takes the following
form,
Current time is 9:03:39.75
Enter new time:
Type the time using the 24-hour clock in the format hh:mm (e.g. 9:15,
or 15:03). If the exact time is not known, enter a reasonable estimate or just
press the <Return> key to accept the time offered.
It is advisable to check the date and time, as these are recorded in the file
directory when files are created or amended.
Note: a lot of PCs now have battery powered clocks which keep a record of the
date and time even when the PC is switched off.
(5) After displaying information about the version of MS-
DOS
being used the MS-
DOS
prompt C> will appear on the screen. The PC is awaiting
instructions. Enter an MS-DOS command or the name of the program to be used.
On booting-up the PC will search the A drive first for a system disk; if none
is found it will then check the hard disk. Thus hard disk systems can be
booted-up from a floppy disk by inserting a system disk in drive A and
following the instructions above. The system will then load from drive A
rather than drive C.
To boot up a PC with twin floppy drives and no hard disk, insert a system disk
in drive A before switching on.
Note : A system disk, either hard or floppy contains a minimum of three
files, two of which are hidden. It is not enough that the files exist
on a disk to make that disk a system disk; the disk has to be formatted as a
system disk (see section 15.1).
There are occasions when it may be necessary to stop what is currently running
on the PC and return to the MS-DOS prompt.
In general, if an application program is running, such as WordPerfect or dBase
IV, there will be a `proper' way to leave the program by selecting the
appropriate Quit, Stop or Exit command. This `proper' way of getting back to
MS-DOS should always be used as the program will have been designed to close
any open files, delete workfiles it has created, etc., on receiving the `Quit'
command.
However, if all else fails, MS-DOS may be restarted. On a hard disk system
first check that there is no disk in drive A. Hold down the <Ctrl> and
<Alt> keys and, while holding them down, press the <Del> key that
is situated at the bottom of the numeric keypad. This is known as a `soft
reset' or `warm boot/start-up' as it reloads the MS-DOS software and resets the
computer to its start-up state. The difference between this and a `hard reset'
or `cold boot/start-up' (turning the PC off and then on again) is that it is
quicker as there is no hardware check.
Most PCs have a RESET button on the front of the main unit which when pressed
performs a soft boot.
Warning: The contents of RAM are lost when a PC is rebooted.
Before floppy disks can be used they have to be formatted for use. This is
done using the external MS-DOS command, FORMAT. The command issued will
depend on disk size and capacity.
Warning
Formatting a disk will erase any information currently stored on the disk. So
take care.
The following commands assume the disk to be formatted is in drive A.
Formatting 51/4" Floppy Disks
To format a double density disk in a double density drive, or a high density
disk in a high density drive, use
FORMAT A:
To format a double density 51/4" disk in a high density (1.2Mb) drive, use
FORMAT A: /4
This will give the disk a capacity of 360Kb.
Formatting 31/2" Floppy Disks
To format a double density disk in a double density drive, or a high density
disk in a high density drive, use
FORMAT A:
To format a double density 31/2" disk on a high density (1.44Mb) drive
FORMAT A: /T:80 /N:9
This will give the disk a capacity of 720Kb.
Warning
Do not format high density 51/4" disks to 360Kb, or double density 51/4" disks
to 1.2Mb. This rule also applies to 31/2" disks.
To format a floppy disk as a bootable system disk use the /S
option. For example
FORMAT B: /S
will format the floppy in drive B as a system disk.
Do not type FORMAT C: unless you want to destroy all the
information on your hard disk!
Copies of floppy disks can be made by using the external command, DISKCOPY.
Both disks need to be of the same size and capacity. Your PC need not have two
identical floppy drives for diskcopy to work; for example, to copy a disk in
drive A use
DISKCOPY A: A:
and follow the on-screen instructions.
The disk to which you are copying need not have been previously formatted.
Warning
Any information stored on the disk to which you are copying will be
erased.
You are strongly recommended to write protect the source disk when using
diskcopy to avoid accidental overwriting.
The external command CHKDSK will scan the specified disk, checking for
errors such as bad sectors. For example
CHKDSK C:
will check all the files on drive C for errors. To fix any errors use the /F
switch. For example
CHKDSK C: /F
As well as checking for errors, CHKDSK will give useful information on disk
space usage.
Information stored on a disk (floppy or hard) is organised into units known as
files. A file may contain, for example, a program, a set of data, or a
document. Each file must be distinguished by being given a filename.
Files can be grouped together in directories.
Filenames are chosen by the user, subject to the following rules,
(1) The length must be from 1 to 8 characters, with no spaces.
(2) The characters must be drawn from the letters A to Z, the digits 0 to 9,
and the additional characters - : $ & ! % ( ) { } ' " _ @
For example,
MY_DOC_2 1986DATA %TOTALS rubbish Club(86)
are valid filenames. Filenames may be referred to in upper or lower case;
they are always translated into upper case. Choose filenames that are
meaningful, i.e. descriptive in some way of the file's contents.
Optionally, a filename may be followed by a file extension. This
consists of from one to three characters and is separated from the filename by
a full stop or `dot'. The purpose of a file extension is to describe the kind
of information held in the file. In many cases they are added automatically by
an application program. For example,
REPORT.DOC for textual data;
TOTALS.WKS could be for a Lotus 1-2-3 worksheet.
The following are some of the commonly used file extensions,
BAS BASIC source file
BAT Batch file
COM Command binary file
DOC Used by many word processors (to mean document)
EXE Executable binary file
FOR FORTRAN source file
SYS System file
Extensions BAT, COM, EXE and SYS are meaningful to the MS-
DOS
operating system and should not be used for general data files. The others are
used as a matter of convention. If the software does not require specified
file extensions to be used, personal extensions may be devised as an extra aid
to identifying the contents of files.
If a file has a file extension, this must be included when using the filename
with an MS-DOS command. For example
C> TYPE REPORT.DOC
will display the contents of the file called REPORT.DOC on the screen.
If the file is not held on the disk in the current drive it will also be
necessary to specify which disk drive contains the disk on which the file is
stored. This is done by adding the drive specifier (A: or C:) to
the front of the filename.
The description of a file, known as a file specification, is
therefore,
<drive letter>:<filename>.<file extension>
For example,
C:PROJECT.DOC
A:TOTALS.BAS
Note: Files in the same disk directory must have unique file specifications.
They may have the same filename provided that they have different file
extensions. For example, TOTALS.BAS and TOTALS.DAT may exist in the same disk
directory.
It is often convenient to give a file specification which corresponds to a
group of files, rather than a single file. This is done by using so-called
wildcard characters. The asterisk ,*, is a wildcard character
and can be used to represent any number of arbitrary characters (including
none) in the filename or file extension. For example
*.DOC refers to all files with an extension of DOC.
FILEA.* refers to all files with the filename FILEA and any file
extension, for example FILEA.DAT, FILEA.TXT.
TEST*.TXT refers to all filenames beginning TEST, and with the extension
TXT, for example TEST.TXT, TESTNEW.TXT, TEST1.TXT.
Note that no characters should follow the * in either the filename or
extension. For example, *T.DOC will be treated as *.DOC.
A second wildcard character, a question mark ,?, is taken to represent
any single character in a filename or file extension. For example
TEST?.TXT refers to TESTl.TXT, TESTA.TXT etc., but not TEST.TXT or
TESTNEW.TXT.
PROG.P?? refers to PROG.PAS, PROG.PRG, etc., but not PROG.PG or PROG.P.
DATA???.TXT refers to DATANEW.TXT, DATAOLD.TXT etc., but not DATA1.TXT.
Note: Not all commands can make use of wildcards.
Files are held in directories on a disk. Initially each disk has one
directory (called the root directory), but sub-directories may be
created. Directories allow files, especially on hard disks, to be kept
together in logically related groups. For example, in a filing cabinet all
letters would be kept together, accounts information would be together and so
would minutes of meetings. On the computer a similar system can be arranged
using directories; files of letters would be in one directory, accounts
information in a second and minutes of meetings in a third. Full details about
directories; how to create them, access files in them and delete them are given
in section 21.
This section covers the commands,
DIR Listing a directory contents.
TYPE Displaying the contents of a file on the screen.
PRINT Listing the contents of a file on the printer.
COPY Copying files.
REN Renaming files.
DEL Deleting files.
The MS-DOS command DIR (DIRectory) gives a list of the filenames in the
current directory. Where there are no user sub-directories on a disk the DIR
command will list every file on the disk.
Hard disks generally have more than one directory and the listing of other
directories can be done either by changing the current directory or specifying
the directory.
To obtain details of the files on a disk in the current directory, type
C> DIR
Volume in drive C is DISK_VOL1
Directory of C:\
COMMAND COM 25276 24-07-87 12:00a
CONFIG SYS 202 21-03-90 10:45a
AUTOEXEC BAT 1024 21-03-90 10:50a
WP51 <DIR> 12-04-90 11:34a
LOTUS <DIR> 12-04-90 2:33p
LETTERS <DIR> 13-04-90 11:22a
6 File(s) 36345210 bytes free
The directory listing produced by the DIR command shows the name and size of
each file in bytes (equivalent to characters, in the case of text files), and
the date and time when the file was created or last altered. The <DIR>
after some of the names indicates that these are sub-directories which may also
contain files. At the beginning of the listing the disk drive is specified and
whether it is labelled. Disks can be labelled when they are formatted, users
are recommended to do this. At the end of the listing, the total number of
files in the current directory and the amount of space still free on the disk
are given.
To obtain details of the files on the disk in drive A, type
C> DIR A:
To obtain details of the file REPORT.DOC on the disk in drive A, type
C> DIR A:REPORT.DOC
Alternatively the current disk drive can first be changed to A and then the
DIR listing done
C> A:
A> DIR REPORT.DOC
To obtain details of a group of files, the wildcard technique described in
section 16.5 may be used. For example
C> DIR C:*.DOC
would give details of all the files in the current directory on the disk in
drive C that have the file extension DOC (the C: could have been omitted in
this example since it is referring to the directory on the current drive).
If there are many files within a directory and the list scrolls off the top of
the screen when the DIR command is issued, using the /W parameter will condense
the display into a multi-column listing.
C> DIR/W
A multicolumn listing includes only the filenames and their extensions, and
the total number of files in the current directory and the free space on the
disk. The date and time of creation or modification and the size of the files
are omitted.
Alternatively, the command
C> DIR/P
gives a list of the files in the current directory which stops after 23
filenames are displayed, with the prompt
Strike a key when ready...
Striking any key will give the next 23 filenames, and so on, until the end of
the directory listing.
If there is a printer attached then the command
C> DIR > PRN
will list the contents of the current directory on the printer. In this
context the `>' is known as the redirection symbol, that is, the output to
the screen is redirected to the printer.
Alternatively, giving the DIR command followed by <Shift/PrtScr> will
print the currently displayed screen.
For more information on sub-directories and how to create them see section
21.
The command TYPE is used to display the contents of a file on the screen. The
external command PRINT will print files on a printer connected to the PC. For
example
C> TYPE FILEA.DOC
will list on the screen the contents of FILEA.DOC. If a file on the disk in
drive A is required then it can be displayed using the command
C> TYPE A:FILEB.DOC
Alternatively the current disk drive can first be changed to A and then the
listing requested.
C> A:
A> TYPE FILEB.DOC
The command PRINT should be used only on a PC with an attached printer. For
example
C> PRINT LETTER.TXT
Files can also be printed using redirection. For example
C> TYPE FILEB.DOC > PRN
The MS-DOS COPY command can be used to copy (or duplicate) a file or files
from one location to another; they may or may not be on the same disk. The
command has the format
C> COPY source-file target-file
For example
C> COPY TESTPROG.DAT NEWPROG.DAT
would make a duplicate copy of the file TESTPROG.DAT under the name
NEWPROG.DAT in the same disk directory.
Warning
The COPY command will overwrite an existing file of the same name and
extension, if such a file is present on the destination disk.
To copy from one disk drive to another, the disk drive name must also be
included. For example
C> COPY MYREPORT.DOC A:
would copy the file MYREPORT.DOC in the current directory on drive C onto the
disk in drive A. In this case, the omission of a filename on drive A means
that the file would have the same name on A.
To copy to a file on another drive and change the name, specify a new filename
in the target file specification. For example
C> COPY CURRENT.DAT A:OLD.DAT
would copy the file CURRENT.DAT in the current directory on drive C into a
file called OLD.DAT on the disk in drive A.
To copy a group of files from one disk to another, the wildcard character may
be included in place of all or part of the filename and/or the file extension.
For example,
C> COPY *.DOC A:
will copy all files with the file extension DOC in the current directory on
drive C into the current directory on the disk in drive A, all the
filenames will be the same as the source filenames. Similarly
C> COPY *.* A:
will copy all the files in the current directory on drive C onto the
current directory of the disk in drive A.
Files can be copied in the opposite direction, i.e. from drive A to the
current directory on drive C. For example
C> COPY A:NEWDOC.TXT
would copy the file NEWDOC.TXT from the disk in drive A into the current
directory on drive C and it will have the same name. Alternatively the current
disk drive can first be changed and then the file copied,
C> A:
A> COPY NEWDOC.TXT C:
In this case the target disk drive must be included.
To copy all the files with a file extension of TXT in drive A to the current
directory on drive C and change their extensions to DOC,
C> COPY A:*.TXT *.DOC
Since the current drive is C the drive name is not necessary before the target
filename. Similarly
C> COPY A:*.*
will copy all the files in the current directory of the disk in drive A into
the current directory on drive C.
The copy command can also be used to print files. For example
C> COPY NEWDOC.TXT PRN
will print the file NEWDOC.TXT on an attached printer.
The RENAME command (or its abbreviation REN) is used to change the name of a
file, for example
C> RENAME FILEA.TXT LETTER.TXT
will rename the file FILEA.TXT in the current directory on drive C. The name
FILEA.TXT will be removed and a directory listing would show the existence of a
file called LETTER.TXT.
To rename a file not on the current disk drive, you must include the drive
name as part of the existing file specification, for example
C> REN A:FILEA.TXT LETTER.*
will rename FILEA.TXT on drive A to LETTER.TXT on drive A. Since the file
extension is not changing the wildcard character is used in the target file
extension.
Alternatively the default drive may first be changed to A and then the file
renamed without specifying the drive name in the file specification,
C> A:
A> REN FILEA.TXT LETTER.*
To RENAME a group of files the wildcard character can be used, for example
C> REN *.DOC *.OLD
will rename all the files with an extension of DOC in the current directory
and give them an extension of OLD.
RENAME will not overwrite an existing file of the same name. If the filename
already exists the following message will be displayed,
Duplicate file name or file not found
Note that this contrasts with the COPY command which gives no warning when a
duplicate file exists and overwrites the file.
The DEL command is used to delete files. The command
C> DEL TEXT1.DOC
will delete the file TEXT1.DOC from the current directory on drive C.
C> DEL A:*.TXT
will erase all the files in the current directory on drive A with an
extension of TXT.
C> DEL TEST*.*
will delete any files in the current directory on drive C with filenames
beginning TEST and any file extension, such as TEST10.DAT, TESTNEW.TXT, etc.
Beware of the command DEL *.* which will delete all the files in the
current directory! (MS-DOS asks you to confirm whether you really want to
delete all the files after this command is issued.) Do not delete any files
called . or .. (these filenames refer to the current and parent
directories; see section 21.2). Do not delete the files called ANSI.SYS,
CONFIG.SYS, AUTOEXEC.BAT, and COMMAND.COM.
All the external commands covered so far, such as PRINT, have file extensions
of either EXE or COM. Any file with such an extension is a program and
can be executed simply by typing its filename, assuming the file is in the
current directory or in a directory contained in the path. Such a file
contains data understandable only by the PC and not you and cannot be PRINTed
or TYPEd. Program files can be grouped into external DOS commands, programs
written by yourself and compiled, and application packages, such as
WordPerfect, written by others. Application packages are discussed later.
To clear the screen type CLS (CLear Screen) in response
to the MS-DOS system prompt. The screen will clear and the system prompt will
be displayed on the top line of a blank screen.
When information is being displayed on the PC's screen, each new line of text
is displayed under the previous one until all possible lines on the screen (24)
have been used. All the lines of text are then moved up one line so that the
top line disappears from the top of the screen, and room is made at the bottom
of the screen for another line. This action is known as scrolling. To
stop the screen scrolling and thus make it pause, hold down <Ctrl> and
press <S> at the same time. To restart the scrolling, press any key (or
<Ctrl/S> again). Alternatively press <Break> and any key to
restart scrolling. This is useful if you are displaying a particularly large
file or a long directory listing.
Alternatively for listing long files you can use the MORE command. For
example,
C> TYPE LONGFILE.DAT | MORE
which works in the same way as the /P switch on the DIR command. The | symbol
is normally obtained by pressing <Shift> and \.
To interrupt the action of any MS-DOS command, such as displaying the contents
of a file, press <Ctrl/C>. The MS-
DOS
system prompt will be displayed. <Ctrl/Break> sometimes works when
<Ctrl/C> does not.
If a mistake is made when typing a command and <Return> has not been
pressed, the error may be corrected using the <Backspace> key to delete
the characters back to the mistake and then retype.
When a command line is entered it is held in a buffer (an area of
memory) until <Return> is pressed when it is transferred to another area
called the template. Therefore the template holds the previous command.
It is possible to retrieve the previous command line from the template by
pressing the function key marked <F3>.
After using an application program, wherever possible leave the program by
means of the appropriate Quit, Exit or Stop command and return to the MS-DOS
prompt before turning off the PC.
Once the MS-DOS system prompt is displaying on the screen, switch off as
follows,
(l) Remove any floppy disks from the disk drives and place them in their
envelopes.
(2) On a hard disk system it is recommended that the read-
heads
on the hard disk are parked. The command to do this varies with manufacturer
(consult the manual provided with your PC), common variations are PARK, DPARK
and FXPARK. The disk park command must be used before a hard disk system is
moved to another location. Some hard disks have automatic disk parking.
(3) Turn off the PC by putting the power switch on the main unit into the off
position.
(4) Turn off the monitor screen and any peripherals.
(5) Turn off at the mains.
Directories allow files to be kept together in logically related groups. For
example, files of letters could be kept in one directory, accounts information
in a second, and minutes of meetings in a third. This section covers the
concepts of directories, their creation and manipulation, and the copying of
files between directories.
Directories are of more value on a hard disk system than on a system using
only floppy disks; because of the greater size of a hard disk it is more
important to keep the data on it in an organised fashion. Normally, on a
system using floppy disks, a separate disk is used for each project although it
is possible to have sub-directories on a floppy disk.
The organisation of the directory structure is based on the concept of a tree.
As with a tree it has a root. This root is the foundation of the directory
structure and all other directories in the system.
When a disk is formatted, the root directory is created automatically; it
cannot be deleted. The root directory is the default directory on start-up
from either a floppy disk or a hard disk. Named directories can then be
created beneath this root directory and further directories beneath these
directories. The following diagram shows how directories in such a hierarchy
relate to each other.
The root directory has the special name \
In the above diagram, the root directory contains a number of files as well as
the three directories ACCOUNTS, SUE, and WP. The directory ACCOUNTS contains a
number of files, the directory SUE contains two sub-directories, DOCS and
LETTERS, as well as some files, and the directory WP contains some files. A
directory which contains one or more sub-directories is called the parent
directory of those sub-directories. In the above example SUE is the parent
directory of DOCS and LETTERS, and the root is the parent directory of
ACCOUNTS, SUE and WP. The terms directory and sub-directory are
used more or less interchangeably.
Directory names follow the same rules as do filenames but do not normally
include an extension, though this is allowed.
The number of files and/or directories in the root directory is limited to 111
on a 360 KB floppy disk and 512 on a 20 Mbyte hard disk, but there is no such
limit within sub-directories. Users are recommended not to have too many files
in any directory as they will become difficult to manage.
You are recommended only to store a minimum of files in the root directory of
the hard disk. Typically the root directory will contain only the files
AUTOEXEC.BAT and CONFIG.SYS (the relevance of these two files are discussed
later). All files relating to the operating system (for example external DOS
commands) are normally stored in a directory called DOS.
The pathname of a given file is the route which must be traversed from the
root directory to reach the directory in which the file resides. For example,
in the above diagram, the path to a file in the directory ACCOUNTS is the
pathname
C:\ACCOUNTS
The \ before ACCOUNTS refers to the root directory. The pathname to a file in
the directory LETTERS under the directory SUE is
C:\SUE\LETTERS
In this example the initial \ refers to the path starting at the root
directory and the second is a separator between directory names on the path.
If there is a file called MAR88.TXT in the directory ACCOUNTS then the pathname
plus filename is
C:\ACCOUNTS\MAR88.TXT
Again the initial \ refers to the root directory and this time the second \ is
the separator between the directory name and the filename.
A full file specification includes the drive name, pathname, filename and
extension. If the file is on the hard disk, i.e. drive C, then the full
file specification would be
C:\ACCOUNTS\MAR88.TXT
In the above diagram of a directory structure, if there is a file called
AUG10.CB in the directory LETTERS under SUE then the full file specification
would be
C:\SUE\LETTERS\AUG10.CB
Files in different directories on the same drive can have the same filename,
but they will have different file specifications owing to the different
pathnames. For example, a file called MAR88.TXT in the directory DOCS under
SUE will have the file specification
C:\SUE\DOCS\MAR88.TXT
and will be distinguished by MS-DOS from the file with the same filename in
the directory ACCOUNTS which would have the file specification
C:\ACCOUNTS\MAR88.TXT
Files within the same directory must, of course, have different combinations
of filename and extension.
In the above examples of pathnames the initial \ refers to the root directory
and subsequent ones are the separators between directory names in the path. A
\ is then used to separate the filename from its directory name. A pathname
not preceded by a \ is taken to be a relative pathname from the current
directory. Examples of relative pathnames are given in section 21.4.
All of the file handling commands can be used to manipulate files not in the
default (current) directory by giving the pathname or the full filename
specification. In the examples below, since the default drive is C, the drive
specification (C:) may be omitted.
(1) To display on the screen the file DATAl.DAT in the directory ACCOUNTS,
C> TYPE C:\ACCOUNTS\DATA1.DAT
(2) To obtain a directory listing of the files in the sub-directory WP,
C> DIR C:\WP
(3) To obtain a directory listing of the files in the directory DOCS under the
directory SUE,
C> DIR C:\SUE\DOCS
(4) To list on the screen the file called AUG10.CB in the sub-directory
LETTERS,
C> TYPE C:\SUE\LETTERS\AUG10.CB
In section 21.2 details are given of how to change the current directory so
that the full file specification does not always have to be used.
By default the system prompt is the name of the current drive followed by an
angle bracket. On a hard disk system this will normally be C> and on a
floppy disk system this will normally be A>. It is possible to change the
default disk drive by typing the new drive name (followed by :). For
example
C> A:
A>
To change the current drive back again to C, type C: followed by
<RETURN>.
The prompt A> appears when MS-DOS is first loaded from a floppy disk to
indicate that drive A is the current drive. This means that MS-DOS will
expect to find the programs required on the disk loaded in drive A unless you
tell it otherwise.
On a PC with two floppy drives to change the current disk drive to drive B,
simply type B: and <Return>. The MS-DOS prompt will then change
to B>. For example
C> B:
B>
To change the current drive back again to drive C, type C: followed by
<Return>. It is also possible to change the default directory from the
root to a sub-directory (see section 21.2). If this is to be done it is useful
if the system prompt indicates which directory you are currently using. The
PROMPT command can be used to make the system prompt indicate the current
directory. For example
C> PROMPT $P$G
will change the default prompt for the current session. The $P causes the
pathname of the current drive name and directory to be displayed as part of the
system prompt. The $G causes the greater than character `>' to be displayed
after the pathname.
For example
C> PROMPT $P$G
C:\>
When the current directory is changed the prompt will change to indicate the
new default directory; in the above case the root directory. If the directory
had been changed to ACCOUNTS the prompt would be
C:\ACCOUNTS>
the directory had been changed to LETTERS under SUE the prompt would be
C:\SUE\LETTERS>
The command PROMPT $P$G is often included by users in their AUTOEXEC.BAT file
which would make it operate automatically on starting up. The AUTOEXEC.BAT
file is a file containing a set of commands which are executed every time the
PC is booted. An example of an AUTOEXEC.BAT file including this command is
given in section 22.2.
The following sections cover the commands,
MKDIR or MD Creating a directory
CHDIR or CD Change the default directory
RMDIR or RD Deleting a directory
DIR Listing a directory contents
The command MKDIR (or its abbreviation MD) is used to create (Make) a
directory. New directories can be created from within the parent directory (or
from any other directory as long as the full path to the new directory is
given). For example
C:\> MKDIR THESIS
will create the directory THESIS under the current directory which in this
case is the root directory. When a directory listing of the root directory is
requested, the entry
THESIS <DIR> date time
will be included in the output.
A directory CHAP1 can then be created under THESIS from the root directory
using the command
C:\> MD THESIS\CHAP1
The full pathname must be given since the directory is being created from the
root directory. It is also possible to change the default directory and then
the sub-directory can be created from the new default directory.
To change the default directory, the CHDIR (or its abbreviation CD) command is
used. To change from the root directory to the newly created directory THESIS
type
C:\> CHDIR THESIS
C:\THESIS>
The directory listing of a new directory which has no files in it will show
two entries
. <DIR> date time
.. <DIR> date time
where . refers to the current working directory
.. refers to the parent directory
In the above example the current working directory is THESIS and the parent
directory is the root directory. The two entries (or pointers) . and .. must
not be deleted.
Note If an attempt is made to delete .. the system responds with the question
Are you sure (Y/N). A reply of Y will delete all
the files in the parent directory!
To change the default directory from the root directory to the directory
called LETTERS under SUE,
C:\> CD SUE\LETTERS
C:\SUE\LETTERS>
When moving to a directory below the current directory in the directory
hierarchy it is not necessary to give the part of the pathname up to the
current directory (i.e. the initial \). For example, to move to the directory
LETTERS from the directory SUE which is the parent directory
C:\SUE> CD LETTERS
C:\SUE\LETTERS>
If CD \LETTERS had been specified the system would expect the directory
LETTERS to be immediately beneath the root directory and the command would have
failed with the message Invalid Directory. Note that changing the
default directory on the non-current drive, for example
A:\> CD C:\SUE
A:\>
does not change the default drive; only the default directory.
To return to the root directory from any sub-directory on the default disk
drive the command
C:\WP> CD \
C:\>
may be used. This means that to move to a directory on another branch of the
tree, for example to move from the directory LETTERS under SUE directly into
the directory THESIS, the command would be
C:\SUE\LETTERS> CD \THESIS
C:\THESIS>
To return to the parent directory of any sub-directory the MS-DOS abbreviation
.. may be used
C:\SUE\LETTERS> CD ..
C:\SUE>
The \ at the beginning of a pathname always indicates the root directory as
the beginning of a search for a directory. For example
C:\ACCOUNTS> CD \SUE\LETTERS
C:\SUE\LETTERS>
will change the default directory to LETTERS. It is a good idea to insert
this backslash and specify the path from the root, since the command will then
work from any sub-directory.
The command CD on its own displays the name of the current directory.
The command RMDIR (or its synonym RD) will delete (ReMove) a directory.
Before this can be done all the files in the directory must be deleted
otherwise the command will fail. If the directory DOCS under SUE is to be
deleted then the following steps must be taken
C:\> CD SUE\DOCS
C:\SUE\DOCS> DEL *.*
Having deleted all the files in the directory DOCS (this can be verified by a
DIR listing and only the two pointers, . and .., will be left)
the default directory must then be changed to the parent directory (SUE),
C:\SUE\DOCS> CD ..
C:\SUE>
The directory DOCS can now be removed.
C:\SUE> RD DOCS
To check that the directory has been deleted issue the following command
C:\SUE> CD DOCS
If the directory has been removed the system will issue the following
message
Invalid directory
As explained previously, the command DIR lists the names of the files in the
current directory. It also gives the names of any sub-directories belonging to
the current directory but does not give the filenames of files in the
sub-directories. For example
C:\> DIR
would give a list of all the files in the current directory, in this case the
root directory. The three sub-directories ACCOUNTS, SUE and WP would be
indicated as follows,
ACCOUNTS <DIR> date time
SUE <DIR> date time
WP <DIR> date time
The following examples show the use of the DIR command to list files in
different directories (the tree structure on page 81 is assumed to exist).
(l) C:\> DIR
will list the names of all the files in the current directory, in this case
the root directory, and the directory names ACCOUNTS, SUE and WP.
(2) C:\> DIR \SUE
will list the names of all the files and sub-directories in the directory
SUE. The \ before SUE is not necessary in this context.
(3) C:\> CD SUE
C:\SUE> DIR
will also list the names of the files in the directory SUE. The default
directory has been changed to SUE before the directory listing is requested.
(4) C:\> DIR \SUE\DOCS
will list the names of the files in the directory DOCS under SUE under the
root directory.
(5) C:\> CD \SUE\DOCS
C:\SUE\DOCS> DIR
will also list the names of the files in the directory DOCS.
(6) C:\SUE\DOCS> DIR ..
will list the names of the files in the parent directory, i.e. SUE, even
though the default directory is DOCS.
(7) C:\SUE\DOCS> DIR \
will list the names of the files in the root directory.
(8) C:\SUE\DOCS> DIR \ /W
will give a multi-column listing of the directories and the names of the
files and their extensions in the root directory.
(9) C:\SUE\DOCS> DIR ..\LETTERS
will list the names of the files in the directory LETTERS.
The options /W and /P can be added to any of the above examples.
The COPY command allows files to be copied from one directory to another as
well as between disks and within the same directory. When copying from one
directory to another the default directory can be any directory.
For example, the file called FILE1.DAT is to be copied from the root directory
(the current default directory) into the directory ACCOUNTS and the name is to
be changed to FILENEW.DAT.
C:\> COPY FILE1.DAT \ACCOUNTS\FILENEW.DAT
will copy the file. Alternatively
C:\> CD ACCOUNTS
C:\ACCOUNTS> COPY \FILE1.DAT FILENEW.DAT
will do the same copy but this time the default directory is ACCOUNTS. If the
filename is to be the same in the new directory then the wildcard character can
be used instead of the second filename. For example
C:\ACCOUNTS> COPY \FILE1.DAT *.*
will give the file the same name in the directory ACCOUNTS as it has in the
root directory. The *.* can be omitted.
If the default directory is the root directory and a file is to be copied from
one directory to another then the full pathname must be given for both the
source and target files. For example
C:\> COPY \SUE\LETTERS\FILE1.DAT \ACCOUNTS\NEWFILE.DAT
will copy the file FILE1.DAT from the directory LETTERS to the directory
ACCOUNTS and change the name to NEWFILE.DAT.
If the target is an existing directory name, the file can be copied into the
directory and given the same name. For example
C:\> COPY \SUE\LETTERS\FILE.DAT \ACCOUNTS
With a hard disk with many sub-directories, changing directories, finding and
copy files, et.c. can be time consuming. Fortunately there are many utility
programs available, such as XTREE, which simplify file handling.
The TREE command displays all of the directories and sub-directories on the
default or a specified disk. For example
C:\> TREE
will display on the screen all the directories and the sub-directories on the
default disk C.
C:\> TREE A:
will display on the screen all the directories on the disk in drive A.
C:\> TREE A:/F
will additionally give the names of the files in all of the directories on the
disk in drive A.
On a hard disk, the MS-DOS external commands are usually placed in a
sub-directory called, for example, DOS. Unless otherwise instructed the system
will only look in the current directory for any commands. The PATH command
allows MS-DOS (and other) commands to be available from whichever directory is
being used by giving a list of alternative directories which are to be
searched.
For example
C:\> PATH C:\;C:\DOS
will set a search path to the root directory and the directory DOS so that
external commands stored in either of them will be available from all other
directories regardless of the current default directory. This holds true for
the current session only.
If the WordPerfect software is placed, for example, in the directory WP51 then
in order to access it, as well as the commands in the directory DOS, the PATH
command would be
C:\> PATH C:\;C:\DOS;C:\WP51
The semicolon separates the different pathnames which are in the order that
they are searched if a command or program is not found in the default
directory.
The command PATH by itself will display the path currently set.
As with the prompt command it is useful to include the path command in the
AUTOEXEC.BAT file. An example of an AUTOEXEC.BAT file containing this command
is given in section 22.2.
Batch files are files which contain a series of MS-DOS commands. They are
useful in that they can be used to execute a number of commands which are used
repeatedly without having to type the commands each time.
All batch files must have a file extension of BAT. When you wish to execute
the commands stored in a batch file, type the name of the file (the file
extension may be omitted); the commands stored in the file will then be
executed sequentially.
Batch files should be created using a text editor. The standard MS-DOS editor
is called EDLIN and will be described in your MS-DOS manual. There are,
however, many other, easier to use, editors available; and in fact the latest
version of MS-DOS, version 5.0, comes with an editor which is a huge
improvement on EDLIN. Note that batch files should generally be text (ASCII)
files, i.e. they must not contain the formatting characters that word
processors insert. They may also be created using a word processing package
such as WordPerfect but must then be saved as ASCII files (using the
<Ctrl/F5> function in WordPerfect).
Another method of creating a batch file is by using the MS-DOS COPY command
with its first parameter CON (CONsole) followed by the name of a file, i.e. a
command of the type
C:/> COPY CON TEST.BAT
This command, means `copy from the console (i.e. the computer's keyboard) to
the file TEST.BAT'. Once this command has been given, everything typed on the
screen will be copied into the named file until an end-of-file marker is
inserted into the file. The end-of-file marker is generated by pressing the
<F6> key followed by <Return> or by pressing <Ctrl/Z>
followed by <Return>. COPY will then display a message indicating that
it has copied the file to disk.
For example
C:\>COPY CON TEST.BAT <Return>
DIR A: <Return>
CHKDSK A: <Ctrl/Z> <Return>
1 File(s) copied
C:\>
If you create a file by this method, you will be unable to make corrections
except within the current line (using the <Backspace> key). If the file
is saved with errors in it you will have to begin again or edit it.
The AUTOEXEC.BAT file is a special batch file, which is executed automatically
upon start up of the system. To ensure that this occurs, the AUTOEXEC.BAT file
must be created within the root directory of the MS-DOS system disk or in the
root directory of the hard disk. Execution of the AUTOEXEC.BAT file causes the
normal MS-DOS date and time prompts to be bypassed; similarly, the MS-DOS
version message is not displayed.
The purpose of the AUTOEXEC.BAT file is to automate a series of commands, for
example to tailor the system to your needs as shown in the following
examples.
(l) Since the MS-DOS date and time prompts are bypassed when the AUTOEXEC.BAT
file is executed, it is a good idea to make the DATE and TIME commands the
first two commands of any AUTOEXEC.BAT file, unless your PC has a battery
powered clock. The commands DATE and TIME display the prompts to check the
date and the time.
ECHO OFF
DATE
TIME
REM This is a remark and has no effect on the
REM execution of the file. It can be used to
REM annotate a batch file
PATH C:\;C:\DOS;C:\WP51;C:\KERMIT;C:\DBASE
KEYB UK
PROMPT $P$G
ECHO OFF stops the commands following it being displayed to the screen as
they are executed. The PATH command ensures that you can use any command
stored in the root and the directories DOS, WP51, KERMIT and DBASE without that
directory having to be the current one. KEYB UK causes the UK keyboard to be
loaded and the [[sterling]] sign will then be available on <Shift/3>.
The command PROMPT $P$G causes the MS-DOS system prompt to be the current
directory's pathname, followed by an angle bracket, as explained earlier.
(2) The following AUTOEXEC.BAT file will load the word processing package
WordPerfect immediately upon start up (on a hard disk system). It will also
cause the files you have created to be written to and read from the directory
WPFILES. As the directory WP51, in which WordPerfect is being stored, is
specified on the PATH command the system will automatically search this
directory for the file WP.EXE which starts WordPerfect.
DATE
TIME
PROMPT $P$G
ECHO OFF
PATH C:\DOS;C:\WP51
KEYB UK
CD \WPFILES
WP
The following batch file is particularly useful for hard disk owners; it is
called FORMAT.BAT and prevents accidental formatting of the hard disk when
intending to format a blank floppy disk, and consequently erasing all your data
from the hard disk. First REN (RENAME) the MS-DOS FORMAT.COM command (on some
PCs the FORMAT command has a file extension of EXE).
C:\DOS> REN FORMAT.COM FORM.COM
In this example it has been RENamed to FORM.COM. Be careful not to REName the
FORMAT command with the name of an already existing MS-DOS command.
Then create a batch file with the name FORMAT.BAT and store the following line
in it,
FORM A:/S
The /S parameter causes the floppy disk being formatted in drive A to be a
bootable one; the /S can be omitted if you just wish to use the disk for data
files. In order to use the batch file simply type FORMAT and press the
<Return> key. You will then be prompted to insert a floppy disk in drive
A and press <Return>, at which point the formatting will occur.
The CONFIG.SYS file, as its name implies, configures the system when the PC is
booted up. In contrast to the AUTOEXEC.BAT file, which contains commands which
can be executed at any time from the DOS prompt, the commands in the CONFIG.SYS
file can only be included in the CONFIG.SYS file.
The CONFIG.SYS file is a text file, created by a text editor. The following
is a typical example of a CONFIG.SYS.
FILES=20
BUFFERS=30
DEVICE=C:\DOS\MOUSE.SYS
The files command sets the number of open files MS-DOS can access. The
buffers command sets the number of disk buffers allocated by MS-DOS on
boot-up (a buffer is an area of memory for temporary storage of disk data).
A lot of applications software require you to set the files and buffers to a
specified value. So you may have to modify the CONFIG.SYS file before using
the application.
The device command installs a device driver on boot-up. In this case
the mouse driver is installed.
The internal MS-DOS command VER, displays the version of MS-DOS being used by
your system. It can be useful to know this since some software packages won't
run on earlier versions of MS-DOS. This is normally only a problem with old
PCs.
As well as using a PC to run your own programs you can also run a wide variety
of application programs, or packages, on your PC.
Different application packages have different hardware requirements. For
example a CAD package may require a 386 PC with a VGA display whereas a
word processing package may run adequately on an XT PC. It is
important to check that your PC (or a PC you are intending to purchase) is
capable of running your desired application package.
Most applications state the hardware configuration required. However it is
worth noting that, although a particular package may run on a particular PC
system, performance may be very poor.
Hardware considerations include processor type (e.g. 286, 386), video display,
co-processor and hard disk size.
The following table gives a list of common applications and popular
solutions.
There is a vast amount of public domain and shareware software available for
the PC. Public Domain software is made available free of charge. Shareware
software is obtainable free of charge but after evaluating the software, and
you wish to continue using it, you are `invited' to register your copy, usually
at a charge of a few dollars (most shareware originates in the USA). Introduction
1.1. What is a PC?
2. The Components of a PC
2.1. The Main Unit
2.1.1. The CPU
2.1.2. Memory
2.1.3. Disk Drives
2.1.4. Ports and Expansion Slots
2.2. The Monitor
2.3. The Keyboard
2.4. Peripherals
2.5. MS-DOS
3. Classifying PCs
3.1. Portable PCs
4. Floppy Disks
4.1. Sizes and Capacities
4.2. Use of Floppy Disks
4.3. Handling Floppy Disks
4.4. Problems With Floppy Disks
5. Hard Disks
5.1. Partitioning a Hard Disk
5.2. Problems With Hard Disks
5.2.1. Viruses
5.3. Backing Up the Hard Disk
5.4. Disk Caching
6. Video Displays
6.1. Varieties of Display Adapters
6.1.1. Hercules Display Adapter
6.1.2. Colour Graphics Adapter (CGA)
6.1.3. Enhanced Graphics Adapter (EGA)
6.1.4. Video Graphics Array (VGA)
6.1.5. Other Display Adapters
6.2. Monitors
7. System Memory
7.1. Expanded and Extended Memory
7.2. Memory Caching
7.3. RAM Disks
7.4. Virtual Memory
7.5. DOS 5
8. Printers and Plotters
8.1. Printer Types
8.1.1. Dot-Matrix Printers
8.1.2. Daisywheel Printers
8.1.3. Laser Printers
8.1.4. Inkjet Printers
8.2. Interfacing Printers
8.3. Using a Printer
8.4. Plotters
9. Maths Co-processors
9.1. Selecting the Correct Co-processor
10. Expansion Slots
10.1. The Bus
11. Mice, Digitizers, and Scanners
11.1. The Mouse
11.2. Digitizers
11.3. Scanners
12. The Keyboard
12.1. Layout of the Keyboard
12.2. Capital Letters and Punctuation Marks
12.3. Numeric Keypad
12.4. Screen Control Keys
12.5. Entering Commands
12.6. Correcting Typing Mistakes
12.7. The Insert Key
12.8. Other Useful Keys
13. What Is MS-DOS?
13.1. Internal and External MS-DOS Commands
14. The Start Up Procedure
14.1. Starting Up MS-DOS
14.2. Restarting MS-DOS
15. MS-DOS and Disks
15.1. Formatting Floppy Disks
15.2. Copying Floppy Disks
15.3. Checking Disks
16. Files and Filenames
16.1. Files
16.2. Filenames
16.3. File Extensions
16.4. File Specifications
16.5. Wildcard Characters
16.6. Directories
17. MS-DOS Commands
17.1. Listing the Contents of a Directory
17.2. Displaying and Printing the Contents of a File
17.3. Copying Files From One Disk to Another
17.4. Renaming Files
17.5. Deleting Files
17.6. Programs
18. Controlling the Screen
18.1. Clearing the Screen
18.2. Stopping the Screen from Scrolling
18.3. Abandoning Commands
18.4. Command Line Editing
19. Ending a Session on the PC
20. More About Directories
20.1. Pathnames
20.2. System Prompts
21. Directory Commands
21.1. Creating a Directory
21.2. Changing the Default Directory
21.3. Deleting a Directory
21.4. Listing the Contents of a Directory
21.5. Copying Files from One Directory to Another
21.6. The TREE Command
21.7. The PATH Command
22. Batch Files
22.1. Creating Batch Files
22.2. The AUTOEXEC.BAT File
22.3. Examples of Batch Files
23. Further MS-DOS
23.1. The CONFIG.SYS File
23.2. The VER Command
24. Application Programs
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