Monthly Archives: May 2015

The elements of computer

Main Memory: Main memory work as a paper.Which corresponds in the  manual calculation.It’s work is to store instruction and data.

CPU:Central Processing Unit.It acts a brain of the computer.

PCU:Program Control Unit is a part of CPU.It fetch instructions from memory and interpret them.It also known as Instruction unit.

ALU:It’s also a part of CPU .Known as arithmetic logic unit.It’s work is to CPU’s data execution or data processing and carries out the instruction.

Brain vs The Computer

We have to use our brain to calculate something manually like we write with pen/pencils for income tax return in the paper where paper act as a storage which is storing info about my/our income tax

The info contains some procedures which is known as algorithm,instructions or programs which carrying out the calculations,numbers or data.

During the calculation data takes process in the human brain which serve as central processor and the  initial,intermediate an final results are included/recorded in the paper.

The brain performs two distinct functions:
1.A control function
2.Executive function.

Control function actually interprets the instructions and check that the instructions performed perfectly and in the proper sequence.
And an executive function performs the specific steps to performs addtition,multiplication,subtraction and division.
Example: A pocket calculator serves as a aid to the brain

Computer Architecture

Computing and Computer:

We can divide the computer and computing in two categories by nature and limitation:

a. The Nature of Compuing:

1.The brain vs the computer
2.Abstract number

b. Limitations of Computer

We can also divide by evolution:

A. THE evolution of computer

First Generation Computer

2nd generation copmputer

3rd generation computer

4th generation computer(VLSI)

We can also divide the VLSI by three categories:

By Integrated Circuits:

IC Density
IC Families

By Processor Architecture:

Personal Computers
Performance Considerations
Performance Measures
Speed Up Technics

By System Architecture:

Basic Organizations
Computer Networks
Parallel Processing

What to do If fresh installed ubuntu does not find wifi ?

What to do If fresh installed ubuntu does not find wifi ?

I have just installed the recent 15.04 ubuntu but after installing the fresh ubuntu I didn’t find wifi

So what I did to restore my wifi

I connected my LAN cable in my laptop’s ethernet port then I opened up terminal and typed


after this command you can restart your system and get your wifi back 🙂

Create subdomain in custom directory in sentora 1.0.0

In this version we can’t define the custom directory after creating a subdomain

So I followed some tricks by researching the net and used my brain to findout how can it be possible 🙂

Ok so at first I logged in the root mysql via phpmyadmin and then created a root ftp account in the sql table and have given access to my root directory of my vps ubuntu linux

and also added the subdomain directory to my custom directory in mysql sentora core table


create a DNS record for subdomain from the Sentora domain management>DNS manager


after logging in via FTP client using root username and password at /etc/sentora/configs/apache at this directory found a file named httpd-vhosts.conf downloaded this file and then changed the document root for the subdomain section on the file then uploaded in the server again and overwrite it with the old one

then just restarted the apache server..

That’s it 🙂

[Caution: Don’t forget to backup the file httpd-vhosts.conf if any error happens then the backup will be helpful in this case]

Edit php.ini file of your VPS via SSH

Use vi editor to open php5’s php.ini file at ubuntu or any debian based os:

Root login to your VPS then write the command

To save this change:

Exit without save:

Restart web server to perform the changes: