NAND Flash vs NOR Flash

NAND Flash vs NOR Flash, originally uploaded by r7aja.

Comparision of NAND and NOR Flash

Warning about Ctrl+C

We do copy various data by ctrl+c for pasting elsewhere.
This copied data is stored in clipboard and is accessible
from the net by a combination of Javascripts and ASP.

Just try this:
1) Copy any text by ctrl+c
2) Click the Link:
http://www.sourcecodesworld.com/special/clipboard.asp

3) You will see the text you copied on the Screen
which was accessed by this web page.

Do not keep sensitive data (like passwords, creditcard numbers, PIN, etc.)
in the clipboard while surfing the web. It is extremely easy to
extract the text stored in the clipboard to steal your sensitive information

Viewing Windows Files

Hope you have installed both windows and linux on the same hard drive.
While running linux, the windows folders will not be visible.
This is because in windows, the files will be in the FAT file-system;
In linux there will ext2fs file-system.

e.g: to view D:drive
[root@AGRAJA ~]#mount -t vfat /dev/sda5 /mnt/wind

Note: there should be a directory named wind under mnt folder.

The contents of the wind folder will be that of the D:drive.
This can be copied to some other location say /home/test.

After copying the mounted files can be unmounted using the following
command:
[root@AGRAJA ~]#umount /dev/sda5

Memory Types

Primary Memory Types
Most of the system's primary memory is located on the system board.
Primary memory typically exists in two or three forms on the system board:

Read-only memory (ROM) contains the computer's permanent startup programs. ROM devices store information in a permanent fashion and are used to hold programs and data that do not change.

Random access memory (RAM)is quick enough to operate directly with the microprocessor and can be read from, and written to, as often as desired. RAM devices retain the information stored in them only as long as electrical power is applied to the IC. Any interruption of power causes the memory contents to vanish.

Cache memory is a fast RAM system designed to hold data recently accessed from the disk drive that the microprocessor may need again.

ROM
ROM (read-only) memory generally holds data that was programmed into it at the factory, and is not intended to be changed.  There are several types of ROM, some of which can be erased and reprogrammed (but not during the normal operation of the computer).

Types of ROM
- Mask-Programmed ROM (MROM) — programmed at the factory.

- Programmable ROM (PROM) — can be custom-programmed by the user (once) using special circuitry.

- Erasable-Programmable ROM (EPROM) — can also be programmed and erased by the user using ultraviolet light and special circuitry external to the computer.

- Electrically Erasable PROM (EEPROM) — can be erased and reprogrammed by special circuitry within the computer.

Non-Volatile Memory
The one thing all forms of ROM have in common is that they are all non-volatile. This means that the data contained in the memory is not lost when the computer is turned off or when electrical power is lost.  This enables the computer to begin reading instructions and data from this type of memory as soon as it is powered up.

Read-Only
The term "Read-Only" truly applies to MROM and PROM memories, which are written once and then cannot be erased or rewritten. The other ROM classes are more appropriately referred to as Read Mostly Memories, where the ratio of Read operations to Write operations is very high.   The generic term "Read-Only" is used with all non-volatile, semiconductor memories that cannot be written to during the normal operation of the computer.

ROM ICs
Every system board contains one or two ROM ICs that hold the system's Basic Input/Output System, or BIOS program. The BIOS program contains the basic instructions for communications between the microprocessor and the various input and output devices in the system.

Firmware
The information in the BIOS represents all the intelligence that the computer has until it can load more information from another source, such as a hard or floppy disk.  The situation in which programs (software) are stored in ROM chips (hardware) on a permanent basis is referred to as firmware.  ROM chips can be located anywhere on the system board, but they are usually easy to recognize due to their relatively large size and immediate proximity to one another.

Flash ROM
Advancements in EEPROM technology have produced Flash ROM devices that enable new BIOS information to be written (downloaded) into the ROM to update it. The download can come from an update disk or another computer.

Flash ROM Information
Unlike RAM ICs, the contents of the Flash ROM remain after the power has been removed from the chip.

Random Access Memory

The other type of high-speed semiconductor memory used with computers and peripheral devices is IC random access memory or RAM. The term "random access" means that any address location in the memory can be accessed as quickly as any other location.

Read/Write Memories
Because there are other types of RAM memory, IC devices used for primary memory are more appropriately referred to as Read/Write (R/W) memories. In the case of primary memory, the generic term "RAM" always refers to semiconductor R/W memory.

Working with Microprocessors
Semiconductor RAM memories are fast enough to work directly with the microprocessor without slowing it down. The computer uses the RAM portion of primary memory to hold programs and data currently being executed by the microprocessor.

RAM Addresses
During the execution of a program, the contents of many RAM address locations are changed as the microprocessor updates the program, by storing intermediate or final results of operations performed.

Types of RAM
Like semiconductor ROM, semiconductor RAM has more than one type. As a matter of fact, it has two general categories: Static RAM (SRAM) Dynamic RAM (DRAM) Although they both perform the same function, the methods they use are completely different

SRAM
Static RAM (SRAM) stores binary bits in such a manner that the bits remain in RAM as long as power to the chip is not interrupted

DRAM
Dynamic RAM (DRAM), on the other hand, requires that stored data be refreshed, or rewritten, periodically to keep it from fading away. As a matter of fact, each bit in the DRAM must be refreshed at least once every 2 milliseconds or the data dissipates

DRAM vs. SRAM
Although the extra circuitry and inconvenience associated with refreshing may initially make DRAM memory seem the obvious second choice behind SRAM, this is not the case.

The Economical Choice
Due to the simplicity of DRAM's internal structure, the bit storage capacity of a DRAM chip is much greater than that of a similar SRAM chip. The DRAM chip also offers a much lower rate of power consumption. Both of these factors contribute to making DRAM memory the economical choice in certain RAM memory systems.

Using SRAM or DRAM
Generally, SRAM is used in smaller memory systems where the added cost of refresh circuitry would greatly add to the cost per bit of storage.  DRAM is used in larger memory systems where the extra cost of refresh circuitry is distributed over a greater number of bits and is offset by the reduced operating cost associated with DRAM chips.

Volatile Memory
Both SRAM and DRAM have the disadvantage of being volatile. This means that any data stored in RAM is lost if power to the computer is disrupted for any reason. On the other hand, both types of RAM have the advantage of being fast: They can be written into and read from with equal ease.

DIP
In earlier PC designs — XT and AT — the system's RAM memory was comprised of banks of discrete RAM ICs in Dual In-line Pin (DIP) sockets.

SIP
Intermediate clone designs placed groups of RAM ICs on small 30-pin daughterboards that plugged into the system board vertically.  This mounting method required less horizontal board space.  These RAM modules had pins along one side of the board and were referred to as single in-line pin (SIP) modules.

SIMMs and DIMMs
Further refinements of the RAM module produced snap-in, single in-line memory modules (SIMMs), and dual in-line memory modules (DIMMs). SIMM and DIMM units mount vertically on the system board. However, rather than using a pin and socket arrangement, both use special snap-in sockets that support the module firmly.

SIMM and DIMM Qualities
SIMMs and DIMMs are also keyed, so that they cannot be plugged in backwards.
SIMMs are available in 30- and 72-pin versions; DIMMs are larger 168-pin boards.

Memory Modules
PCs are usually sold with less than their full RAM capacity. This enables a user to purchase a less expensive computer to fit the user's individual needs, and yet retain the option to install more RAM if future applications call for it.

Creating a linux man page

Structure of a Man page

Header Name Synopsis Description Options Resources Diagnostics See also
Copyright Bugs Authors

mymanpage.1 —————————————————————

.TH MYMANPAGE 1

.SH NAME mymanpage \- A Demo

.SH SYNOPSIS .B mymanpage [\-option …]

.SH DESCRIPTION .PP \fImymanpage\fP is a complete application that does
nothing useful.

.PP It was written for demo

.SH OPTIONS .PP It doesn't have any, but let's pretend, to make this
template complete:

.TP .BI \-option If there was an option …

.SH RESOURCES .PP mymanpage uses almost no resources.

.SH DIAGNOSTICS The program should provide info about what it does

.SH SEE ALSO The only other program we know with this little
functionality is the hello world application.

.SH COPYRIGHT

This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.

.SH BUGS There were a few bugs

.SH AUTHORS Raja AG

———————————————————–

After saving the file, type at the terminal: [root@AGRAJA~]#groff
-Tascii -man mymanpage.1

Installing the man page: [root@AGRAJA~]#gzip mymanpage.1
[root@AGRAJA~]#cp mymanpage.1.gz /usr/share/man/man1

Test the man page: [root@AGRAJA~]#man mymanpage

Excel Keyboard Shortcuts

Shortcut key

Action             Menu Equivalent                     Comments                                Version

Ctrl+A	Select All	None	All
Ctrl+B	Bold	Format, Cells, Font, Font Style, Bold	All
Ctrl+C	Copy	Edit, Copy	All
Ctrl+D	Fill Down	Edit, Fill, Down	All
Ctrl+F	Find	Edit, Find	All
Ctrl+G	Goto	Edit, Goto	All
Ctrl+H	Replace	Edit, Replace	All
Ctrl+I	Italic	Format, Cells, Font, Font Style, Italic	All
Ctrl+K	Insert Hyperlink	Insert, Hyperlink	Excel 97/2000
Ctrl+N	New Workbook	File, New	All
Ctrl+O	Open	File, Open	All
Ctrl+P	Print	File, Print	All
Ctrl+R	Fill Right	Edit, Fill Right	All
Ctrl+S	Save	File, Save	All
Ctrl+U	Underline	Format, Cells, Font, Underline, Single	All
Ctrl+V	Paste	Edit, Paste	All
Ctrl W	Close	File, Close	Excel 97/2000
Ctrl+X	Cut	Edit, Cut	All
Ctrl+Y	Repeat	Edit, Repeat	All
Ctrl+Z	Undo	Edit, Undo	All
F1	Help	Help, Contents and Index	All
F2	Edit	None	All
F3	Paste Name	Insert, Name, Paste	All
F4	Repeat last action	Edit, Repeat. Works while not in Edit mode.	All
F4	While typing a formula, switch between absolute/relative refs	None	All
F5	Goto	Edit, Goto	All
F6	Next Pane	None	All
F7	Spell check	Tools, Spelling	All
F8	Extend mode	None	All
F9	Recalculate all workbooks	Tools, Options, Calculation, Calc,Now	All
F10	Activate Menubar	N/A	All
F11	New Chart	Insert, Chart	All
F12	Save As	File, Save As	All
Ctrl+:	Insert Current Time	None	All
Ctrl+;	Insert Current Date	None	All
Ctrl+"	Copy Value from Cell Above	Edit, Paste Special, Value	All
Ctrl+'	Copy Fromula from Cell Above	Edit, Copy	All
Shift	Hold down shift for additional functions in Excel's menu	none	Excel 97/2000
Shift+F1	What's This?	Help, What's This?	All
Shift+F2	Edit cell comment	Insert, Edit Comments	All
Shift+F3	Paste function into formula	Insert, Function	All
Shift+F4	Find Next	Edit, Find, Find Next	All
Shift+F5	Find	Edit, Find, Find Next	All
Shift+F6	Previous Pane	None	All
Shift+F8	Add to selection	None	All
Shift+F9	Calculate active worksheet	Calc Sheet	All
Shift+F10	Display shortcut menu	None	All
Shift+F11	New worksheet	Insert, Worksheet	All
Shift+F12	Save	File, Save	All
Ctrl+F3	Define name	Insert, Names, Define	All
Ctrl+F4	Close	File, Close	All
Ctrl+F5	XL, Restore window size	Restore	All
Ctrl+F6	Next workbook window	Window, ...	All
Shift+Ctrl+F6	Previous workbook window	Window, ...	All
Ctrl+F7	Move window	XL, Move	All
Ctrl+F8	Resize window	XL, Size	All
Ctrl+F9	Minimize workbook	XL, Minimize	All
Ctrl+F10	Maximize or restore window	XL, Maximize	All
Ctrl+F11	Inset 4.0 Macro sheet	None in Excel 97. In versions prior to 97 - Insert, Macro, 4.0 Macro	All
Ctrl+F12	File Open	File, Open	All
Alt+F1	Insert Chart	Insert, Chart...	All
Alt+F2	Save As	File, Save As	All
Alt+F4	Exit	File, Exit	All
Alt+F8	Macro dialog box	Tools, Macro, Macros in Excel 97 Tools,Macros - in earlier versions	Excel 97/2000
Alt+F11	Visual Basic Editor	Tools, Macro, Visual Basic Editor	Excel 97/2000
Ctrl+Shift+F3	Create name by using names of row and column labels	Insert, Name, Create	All
Ctrl+Shift+F6	Previous Window	Window, ...	All
Ctrl+Shift+F12	Print	File, Print	All
Alt+Shift+F1	New worksheet	Insert, Worksheet	All
Alt+Shift+F2	Save	File, Save	All
Alt+=	AutoSum	No direct equivalent	All
Ctrl+`	Toggle Value/Formula display	Tools, Options, View, Formulas	All
Ctrl+Shift+A	Insert argument names into formula	No direct equivalent	All
Alt+Down arrow	Display AutoComplete list	None	Excel 95
Alt+'	Format Style dialog box	Format, Style	All
Ctrl+Shift+~	General format	Format, Cells, Number, Category, General	All
Ctrl+Shift+!	Comma format	Format, Cells, Number, Category, Number	All
Ctrl+Shift+@	Time format	Format, Cells, Number, Category, Time	All
Ctrl+Shift+#	Date format	Format, Cells, Number, Category, Date	All
Ctrl+Shift+$	Currency format	Format, Cells, Number, Category, Currency	All
Ctrl+Shift+%	Percent format	Format, Cells, Number, Category, Percentage	All
Ctrl+Shift+^	Exponential format	Format, Cells, Number, Category,	All
Ctrl+Shift+&	Place outline border around selected cells	Format, Cells, Border	All
Ctrl+Shift+_	Remove outline border	Format, Cells, Border	All
Ctrl+Shift+*	Select current region	Edit, Goto, Special, Current Region	All
Ctrl++	Insert	Insert, (Rows, Columns, or Cells) Depends on selection	All
Ctrl+-	Delete	Delete, (Rows, Columns, or Cells) Depends on selection	All
Ctrl+1	Format cells dialog box	Format, Cells	All
Ctrl+2	Bold	Format, Cells, Font, Font Style, Bold	All
Ctrl+3	Italic	Format, Cells, Font, Font Style, Italic	All
Ctrl+4	Underline	Format, Cells, Font, Font Style, Underline	All
Ctrl+5	Strikethrough	Format, Cells, Font, Effects, Strikethrough	All
Ctrl+6	Show/Hide objects	Tools, Options, View, Objects, Show All/Hide	All
Ctrl+7	Show/Hide Standard toolbar	View, Toolbars, Stardard	All
Ctrl+8	Toggle Outline symbols	None	All
Ctrl+9	Hide rows	Format, Row, Hide	All
Ctrl+0	Hide columns	Format, Column, Hide	All
Ctrl+Shift+(	Unhide rows	Format, Row, Unhide	All
Ctrl+Shift+)	Unhide columns	Format, Column, Unhide	All
Alt or F10	Activate the menu	None	All
Ctrl+Tab	In toolbar: next toolbar	None	Excel 97/2000
Shift+Ctrl+Tab	In toolbar: previous toolbar	None	Excel 97/2000
Ctrl+Tab	In a workbook: activate next workbook	None