The word Cryptography is somehow a rarely used word in the common conversations and even in some cases; some people have not even heard this word. The origin of the word Cryptography is form the combination of two Greek words kryptos, meaning “hidden” and gráphō, meaning “I write”. The main question now is that: What is the use of Cryptography?

Generally speaking, whatever done on the internet, cell phone, computers and any digital gadgets that need to be safe against unauthorized access use cryptography. Just to give a simple example, let’s have a brief review to what most people do in their daily life with their computer: assume Alice turns on her PC and just when her operating system loaded, she is asked to enter the login password, which she already has set to prevent others from accessing her private data, this password in fact is used to encrypt some data and secure the drives and files inside the hard disk and provide Security for Alice. The act of encryption or coding data is one of the main aspects of cryptography and the person who designs a cryptographic system is called the cryptographist which I believe in an Artist.

Then she (Alice) opens the web browser and tries logging in, into her email; there are a huge amount of cryptographic operations done to bring her the secure communication with the intended mail server. Then she wants to send an email to her friend Bob, the email is digitally signed so that Bob makes sure that the mail is sent from Alice and not anyone else pretending to be Alice. This story can go much further if Alice just wants to buy something from internet or control her bank account.

In fact cryptography involves all the efforts for providing secure communication and keeping secrets from unauthorized parties. Cryptography can be divided into three major branches

1.       Private Key Cryptography

2.       Public Key Cryptography

3.       Un-keyed Systems

In here I just give a very short and brief introduction to these branches and the coming articles I will give more detailed descriptions.

Most of the history of the cryptography is concentrated on Private Key Cryptography, in these systems the main goal is to code data in such a way that just the people who have the key can de-code the data. The data which is intended to be coded is called the Plain-text, and mostly is shown with the word P the coded data is called the cipher-text or the cipher, and is shown as C. The decoded data is shown with D in the formulations. There exists a key in all the Private Key Cryptography systems and the person who has the encryption and decryption machinery and the key can decrypt the cipher-text using it. Imagine Alice wants to send a message to Bob they both have the encryption and decryption machinery (in cryptography it’s assumed that everyone has access the encryption and decryption machinery and just the key is call the secret parameter).

Alice encrypts P using function E() and sends it through an insecure communication channel like blackboard in a class! Bob can read the cipher-text and uses the decryption machinery or the decryption function D() and decrypts the cipher-text.

A notebook computer is designed to be slightly smaller than a laptop. It is called a notebook computer because it is convenient and portable just like a regular notebook is. Than there are of course sub notebooks. They are substantially smaller than notebooks and laptops and they are intended for traveling businessmen who do a lot of work and travel on the road. A lot of traveling sales people use them.

There are also Palmtop computers. But of course these are very rare and extremely expensive at least outside of Japan these days. They are typically made by the computer hardware computer Toshiba. They usually run on the software Windows 9x. The palmtop computers do have a keyboard on them but they are very close together so these computers are not designed for extensive typing but mostly for email, internet access, or just simple field work.

Portable computers really have evolved over the past three decades just like their desktop counter tops. It used to be portable computers were the size of large suitcases. Compaq was the computer hardware company to be the first to market portable computers. In the early 1980's the size and weight were very laughable compared to the portable computers today. But that time they were cutting edge technology for that time period.

The portable computer systems today are less upgradeable or repairable than desktop computers. However portable systems have no need for ribbon cables because they typically use modular components with snap-in connectors. There is only one problem with replacing components in portable systems which is that the hardware tends to be much less generic than it is in desktops.

The majority of laptops and notebooks use multiprocessors. Most portable systems today use the Pentium III, Celeron, or Pentium 4 processor.

Adding memory to a computer is a very common upgrade and notebooks and laptops are no exception. But of course a memory storage on a portable system will last a whole lot longer and faster than the memory on a desktop. Hard disk drive technology is also hardly unchanged in notebook computers. Some systems use a caddy to hold the drive and make the electrical and data connections to the computer system. This makes the physical part of an upgrade as easy as inserting a new drive into the caddy and then mounting it into the system.

Many manufacturers have adapted the 2-½ inch Compaq hard drives on the market for after market use in older notebooks, many of which that have hard drives under 2 GB in size. The Personal Computer Memory Card International Association has established several standards for credit card size expansion boards that fit into a small slot on laptops and notebooks.

PC card and laptop and notebook slots enable you to add memory expansion cards.

Now of course let's talk about the keyboards of a notebook or laptop. The portable computer system has a built in keyboard as you all know which of course makes it very difficult to fix or replace. The numeric keypad should always be the first to go into the notebooks keyboard. Most portable system keyboards are almost the exact same size as that of a desktop. If you plan to perform a lot of numeric data entry with your portable system, look for numeric keypads that can plug right into your system and override the embedded keypad.

Now I will go on about the history of the floppy disk drive. Alan Shugart is responsible for the creation of the floppy. He was an employee of IBM back in 1967 and that was the year when he invented it. At that time the floppy disk was practically 8 inches in diameter and contained very little memory storage. However at that time in 1967 it was very advanced and very state of the art.

The head actuator is what moves the heads across the floppy disk and is driven by a special kind of motor called a stepper motor. This type of motor does not spin in a circular motion, rather this motor turns a distance and stops. A disk drive always has one or more circuit logic boards.

The standard interface used by all computer floppy disk drives is termed the Shugart Associates SA-400 interface, which was invented in the late 1970s and is based on the NEC 765 chip.