BUS LINES & SYSTEM COMPONENTS

Bus lines provide data pathways that connect various system components.

A Bus line- also know as data bus or simply bus connects the part of the CPU to each other. It also links the CPU to various other components on the system board. A bus is a data roadway along which bits travel. Such data pathways resemble a multilane highway. The more lanes there are. tje faster traffic cam go through. Similarly, the greater the capacity of a bus, the more powerful and faster the operation. A 64-Bit bus has greater capacity than a 32 - Bit bus.

A system unit has more than one type of bus line. The principal bus lines (or "architectures") are :
  • Industry standard architecture (ISA) was developped for the IBM Personal Computer. First it was an 8-Bit wide data path; then it was 16 Bits wide. Although too slow for may of today's application, the ISA but is still widely used.
  • Peripheral component interconnect (PCI) was originally developed to meet the video demands of graphical user interfaces, PCI is a high-speed 32 Bit or 64-Bit bus that is over 20 times faster than ISA buses. The PCI is expected to replace the ISA bus in the near future. PCI buses are widely used to connect the CPU, memory and expansion boards.
  • Accellerated graphics port (AGP) is over twice as fast as the PCI bus. While the PCI bus is used for a variety of purposes, the AGP bus is dedicated to the acceleration of graphics performance. Widely used for graphics and 3-D animations, the AGP is replacing the PCI bus for the transfer of video data.

DO YOU KNOW WHAT IS SYSTEM EVALUATION

Once the new system is implemented and put to operation, it is necessary to evaluate the system to verify whether it is meeting its objectives. These objectives of the system are clearly stated during its problem analysis and system planning phase. The post implementation system evaluation is normally carried out by people who have an independent viewpoint, and are not responsible for the development and maintenance of the system. While evaluating a system, the following points are normally considered:
  1. Performance Evaluation: The performance of the new system is evaluated and compared with the performance of the old system. In generally, the new system should be at least as efficient as the old one in performance. In case of any slack, the reason is analyzed, and if possible, necessary changes are incorporated in the new system to rectify it.
  2. Cost Analysis: It should be analyzed whether the cost estimates done for the various phases of the project, during the planning phase in the beginning, matches with the actual cost incurred in each phase. In case of discrepancies, the cost analysis will help in finding out the reasons. The knowledge can be used in making correct cost estimates for the new systems, which will be designed in future.
  3. Time Analysis: It should be analyzed whether the time estimates done for the various phases of the project, during the planning phase in the beginning, matches with the actual time taken in each phase. In case of discrepancies, the time analysis will help in finding out the reasons. The knowledge can be used in making correct time estimates for the new systems, which will be designed in future.
  4. User Satisfaction: It should be found out whether the users are satisfied with the new system. How useful is the system for them? How enthusiastic are they about the service they receive? Do they received outputs in time to take necessary action? The morale of people using or affected by a system is a good measure of the success of the system.
  5. Ease of Modification: Sooner or later, all systems need to be modified due to one or more of the reasons mentioned in the next section. Hence, the ease with which a system can be modified to incorporate the suggested changes is also an important parameter to judge the quality of the system.
  6. Failure Rate: The quality of a system also depends on its failure rate. A system, which frequently fails cannot meet its objectives successfully. Hence, it is of poor quality.

Graphic Presentation in MS Word

The power graphics is demonstrated through business graphics software in the industry today. Features covered include making presentations and combining information from other application packages such as spreadsheets and databases.
  • Start MS Word Applications.
  • Set Line Spacing to 1.5 inches.
  • Type the above matter in Microsoft Work and save the document in "My Document" folder with any file name.
  • Use Universe font and set font size to 16 for title of the document. Underline the title and use Bold style.
  • Use Verdena font for subtitles in the document. Set font size to 13 and change found style to italic.
  • Use "Print Preview" command to see the preview and change zoom levels.
  • Save the Document with file name assignment 2 using Save AS command in the folder of your name. Use Create New Folder Icon to Create New Folder of your name.
  • See the Web Page Preview of the Document created by you.
  • Use Properties option in File menu and observe the use of this option.
  • Use Exit command to exit from Microsoft Word Application.
Sourse: Computer Fundamentls (Acci.-8)

WINDOWS & CMD COMMAND

Starts a new instance of the Windows XP command interpreter

CMD [/A | /U] [/Q] [/D] [/E:ON | /E:OFF] [/F:ON | /F:OFF] [/V:ON | /V:OFF]
[[/S] [/C | /K] string]

/C Carries out the command specified by string and then terminates
/K Carries out the command specified by string but remains
/S Modifies the treatment of string after /C or /K (see below)
/Q Turns echo off
/D Disable execution of AutoRun commands from registry (see below)
/A Causes the output of internal commands to a pipe or file to be ANSI
/U Causes the output of internal commands to a pipe or file to be
Unicode
/T:fg Sets the foreground/background colors (see COLOR /? for more info)
/E:ON Enable command extensions (see below)
/E:OFF Disable command extensions (see below)
/F:ON Enable file and directory name completion characters (see below)
/F:OFF Disable file and directory name completion characters (see below)
/V:ON Enable delayed environment variable expansion using ! as the
delimiter. For example, /V:ON would allow !var! to expand the
variable var at execution time. The var syntax expands variables
at input time, which is quite a different thing when inside of a FOR
loop.
/V:OFF Disable delayed environment expansion.

Note that multiple commands separated by the command separator '&&'
are accepted for string if surrounded by quotes. Also, for compatibility
reasons, /X is the same as /E:ON, /Y is the same as /E:OFF and /R is the
same as /C. Any other switches are ignored.

If /C or /K is specified, then the remainder of the command line after
the switch is processed as a command line, where the following logic is
used to process quote (") characters:

1. If all of the following conditions are met, then quote characters
on the command line are preserved:

- no /S switch
- exactly two quote characters
- no special characters between the two quote characters,
where special is one of: &<>()@^|
- there are one or more whitespace characters between the
the two quote characters
- the string between the two quote characters is the name
of an executable file.

2. Otherwise, old behavior is to see if the first character is
a quote character and if so, strip the leading character and
remove the last quote character on the command line, preserving
any text after the last quote character.

If /D was NOT specified on the command line, then when CMD.EXE starts, it
looks for the following REG_SZ/REG_EXPAND_SZ registry variables, and if
either or both are present, they are executed first.

HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\AutoRun

and/or

HKEY_CURRENT_USER\Software\Microsoft\Command Processor\AutoRun

Command Extensions are enabled by default. You may also disable
extensions for a particular invocation by using the /E:OFF switch. You
can enable or disable extensions for all invocations of CMD.EXE on a
machine and/or user logon session by setting either or both of the
following REG_DWORD values in the registry using REGEDT32.EXE:

HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\EnableExtensions

and/or

HKEY_CURRENT_USER\Software\Microsoft\Command Processor\EnableExtensions

to either 0x1 or 0x0. The user specific setting takes precedence over
the machine setting. The command line switches take precedence over the
registry settings.

The command extensions involve changes and/or additions to the following
commands:

DEL or ERASE
COLOR
CD or CHDIR
MD or MKDIR
PROMPT
PUSHD
POPD
SET
SETLOCAL
ENDLOCAL
IF
FOR
CALL
SHIFT
GOTO
START (also includes changes to external command invocation)
ASSOC
FTYPE

To get specific details, type commandname /? to view the specifics.

Delayed environment variable expansion is NOT enabled by default. You
can enable or disable delayed environment variable expansion for a
particular invocation of CMD.EXE with the /V:ON or /V:OFF switch. You
can enable or disable completion for all invocations of CMD.EXE on a
machine and/or user logon session by setting either or both of the
following REG_DWORD values in the registry using REGEDT32.EXE:

HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\DelayedExpansion

and/or

HKEY_CURRENT_USER\Software\Microsoft\Command Processor\DelayedExpansion

to either 0x1 or 0x0. The user specific setting takes precedence over
the machine setting. The command line switches take precedence over the
registry settings.

If delayed environment variable expansion is enabled, then the exclamation
character can be used to substitute the value of an environment variable
at execution time.

File and Directory name completion is NOT enabled by default. You can
enable or disable file name completion for a particular invocation of
CMD.EXE with the /F:ON or /F:OFF switch. You can enable or disable
completion for all invocations of CMD.EXE on a machine and/or user logon
session by setting either or both of the following REG_DWORD values in
the registry using REGEDT32.EXE:

HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\CompletionChar
HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\PathCompletionChar

and/or

HKEY_CURRENT_USER\Software\Microsoft\Command Processor\CompletionChar
HKEY_CURRENT_USER\Software\Microsoft\Command Processor\PathCompletionChar

with the hex value of a control character to use for a particular
function (e.g. 0x4 is Ctrl-D and 0x6 is Ctrl-F). The user specific
settings take precedence over the machine settings. The command line
switches take precedence over the registry settings.

If completion is enabled with the /F:ON switch, the two control
characters used are Ctrl-D for directory name completion and Ctrl-F for
file name completion. To disable a particular completion character in
the registry, use the value for space (0x20) as it is not a valid
control character.

Completion is invoked when you type either of the two control
characters. The completion function takes the path string to the left
of the cursor appends a wild card character to it if none is already
present and builds up a list of paths that match. It then displays the
first matching path. If no paths match, it just beeps and leaves the
display alone. Thereafter, repeated pressing of the same control
character will cycle through the list of matching paths. Pressing the
Shift key with the control character will move through the list
backwards. If you edit the line in any way and press the control
character again, the saved list of matching paths is discarded and a new
one generated. The same occurs if you switch between file and directory
name completion. The only difference between the two control characters
is the file completion character matches both file and directory names,
while the directory completion character only matches directory names.
If file completion is used on any of the built in directory commands
(CD, MD or RD) then directory completion is assumed.

The completion code deals correctly with file names that contain spaces
or other special characters by placing quotes around the matching path.
Also, if you back up, then invoke completion from within a line, the
text to the right of the cursor at the point completion was invoked is
discarded.

The special characters that require quotes are:

&()[]{}^=;!'+,`~

REPLACE COMMAND IS USED AS DATABASE AND OTHER APPLICATIONS

The Windows 95 to Windows 2007 all versions followed the Replace command which is use for to replace files or to replace any word as well as used this command as database.

Replaces files.

REPLACE [drive1:][path1]filename [drive2:][path2] [/A] [/P] [/R] [/W]
REPLACE [drive1:][path1]filename [drive2:][path2] [/P] [/R] [/S] [/W] [/U]

[drive1:][path1]filename Specifies the source file or files.
[drive2:][path2] Specifies the directory where files are to be
replaced.
/A Adds new files to destination directory. Cannot
use with /S or /U switches.
/P Prompts for confirmation before replacing a file or
adding a source file.
/R Replaces read-only files as well as unprotected
files.
/S Replaces files in all subdirectories of the
destination directory. Cannot use with the /A
switch.
/W Waits for you to insert a disk before beginning.
/U Replaces (updates) only files that are older than
source files. Cannot use with the /A switch.

"SET" Command is used to dispplay System Annalysis Configuration.

Displays, sets, or removes cmd.exe environment variables.

SET [variable=[string]]

variable Specifies the environment-variable name.
string Specifies a series of characters to assign to the variable.

Type SET without parameters to display the current environment variables.

If Command Extensions are enabled SET changes as follows:

SET command invoked with just a variable name, no equal sign or value
will display the value of all variables whose prefix matches the name
given to the SET command. For example:

SET P

would display all variables that begin with the letter 'P'

SET command will set the ERRORLEVEL to 1 if the variable name is not
found in the current environment.

SET command will not allow an equal sign to be part of the name of
a variable.

Two new switches have been added to the SET command:

SET /A expression
SET /P variable=[promptString]

The /A switch specifies that the string to the right of the equal sign
is a numerical expression that is evaluated. The expression evaluator
is pretty simple and supports the following operations, in decreasing
order of precedence:

() - grouping
! ~ - - unary operators
* / % - arithmetic operators
+ - - arithmetic operators
<< >> - logical shift
& - bitwise and
^ - bitwise exclusive or
| - bitwise or
= *= /= %= += -= - assignment
&= ^= |= <<= >>=
, - expression separator

If you use any of the logical or modulus operators, you will need to
enclose the expression string in quotes. Any non-numeric strings in the
expression are treated as environment variable names whose values are
converted to numbers before using them. If an environment variable name
is specified but is not defined in the current environment, then a value
of zero is used. This allows you to do arithmetic with environment
variable values without having to type all those % signs to get their
values. If SET /A is executed from the command line outside of a
command script, then it displays the final value of the expression. The
assignment operator requires an environment variable name to the left of
the assignment operator. Numeric values are decimal numbers, unless
prefixed by 0x for hexadecimal numbers, and 0 for octal numbers.
So 0x12 is the same as 18 is the same as 022. Please note that the octal
notation can be confusing: 08 and 09 are not valid numbers because 8 and
9 are not valid octal digits.

The /P switch allows you to set the value of a variable to a line of input
entered by the user. Displays the specified promptString before reading
the line of input. The promptString can be empty.

Environment variable substitution has been enhanced as follows:

%PATH:str1=str2%

would expand the PATH environment variable, substituting each occurrence
of "str1" in the expanded result with "str2". "str2" can be the empty
string to effectively delete all occurrences of "str1" from the expanded
output. "str1" can begin with an asterisk, in which case it will match
everything from the beginning of the expanded output to the first
occurrence of the remaining portion of str1.

May also specify substrings for an expansion.

%PATH:~10,5%

would expand the PATH environment variable, and then use only the 5
characters that begin at the 11th (offset 10) character of the expanded
result. If the length is not specified, then it defaults to the
remainder of the variable value. If either number (offset or length) is
negative, then the number used is the length of the environment variable
value added to the offset or length specified.

%PATH:~-10%

would extract the last 10 characters of the PATH variable.

%PATH:~0,-2%

would extract all but the last 2 characters of the PATH variable.

Finally, support for delayed environment variable expansion has been
added. This support is always disabled by default, but may be
enabled/disabled via the /V command line switch to CMD.EXE. See CMD /?

Delayed environment variable expansion is useful for getting around
the limitations of the current expansion which happens when a line
of text is read, not when it is executed. The following example
demonstrates the problem with immediate variable expansion:

set VAR=before
if "%VAR%" == "before" (
set VAR=after
if "%VAR%" == "after" @echo If you see this, it worked
)

would never display the message, since the %VAR% in BOTH IF statements
is substituted when the first IF statement is read, since it logically
includes the body of the IF, which is a compound statement. So the
IF inside the compound statement is really comparing "before" with
"after" which will never be equal. Similarly, the following example
will not work as expected:

set LIST=
for %i in (*) do set LIST=%LIST% %i
echo %LIST%

in that it will NOT build up a list of files in the current directory,
but instead will just set the LIST variable to the last file found.
Again, this is because the %LIST% is expanded just once when the
FOR statement is read, and at that time the LIST variable is empty.
So the actual FOR loop we are executing is:

for %i in (*) do set LIST= %i

which just keeps setting LIST to the last file found.

Delayed environment variable expansion allows you to use a different
character (the exclamation mark) to expand environment variables at
execution time. If delayed variable expansion is enabled, the above
examples could be written as follows to work as intended:

set VAR=before
if "%VAR%" == "before" (
set VAR=after
if "!VAR!" == "after" @echo If you see this, it worked
)

set LIST=
for %i in (*) do set LIST=!LIST! %i
echo %LIST%

If Command Extensions are enabled, then there are several dynamic
environment variables that can be expanded but which don't show up in
the list of variables displayed by SET. These variable values are
computed dynamically each time the value of the variable is expanded.
If the user explicitly defines a variable with one of these names, then
that definition will override the dynamic one described below:

%CD% - expands to the current directory string.

%DATE% - expands to current date using same format as DATE command.

%TIME% - expands to current time using same format as TIME command.

%RANDOM% - expands to a random decimal number between 0 and 32767.

%ERRORLEVEL% - expands to the current ERRORLEVEL value

%CMDEXTVERSION% - expands to the current Command Processor Extensions
version number.

%CMDCMDLINE% - expands to the original command line that invoked the
Command Processor.