Inside the Memory

Computer Memory comes in two basic types : RAM (Random Access Memory) and ROM (Read Only Memory).

In memory, each types of memory has number of cells (storage location) and each cell has unique address. The lowest address is typically '0' and highest address is determined by processor. This range of address is known as machine address space. When computer wants to read/write a location in memory it needs to do 2 things :

1. Specify an address
2. Read or write an address location

 This is done by placing the address on address bus where it is carried to memory/processor. Processor also specifies whether it wants to read/write on specified location. If the processor specifies writes or read operation, then the processor places information on the data bus, address on the address bus and copies the data to the specified location. This mechanism supports JVIV architecture.

Computer Architecture

One of the great success and failures towards the development of computer was Babbage Folly Machine which was supposed to be first automatic mechanical computer but it never worked. The machine however generated the idea about processing the information.

Babbage divided the machine into three parts:

1. Store
2. Mill
3. Control

The Store is what we call memory on today's days. Folly machine had 2 stores : 1 for holding data and other for holding the instruction which is told what to happen to the data. The Mill is the part of the machine that performs instruction on the data. The Control is the part which over saw the movement of data and instructions. 

 First Electronic Computer

During 1940s, the 'MARK' series of computer were developed at Harvard University. It stored and counted numbers mechanically using 3,000 decimal storage wheels, 1,400 rotatory dial switches, 500 miles of wires. It was programmed by using punch cards, and it weighed 5 tons and could do multiplication operation in 6 seconds. MARK-I computer stored data in a separate part of machine from the instruction. The instructions were stored in different format than the data. This technique has been recognized as 'Harvard architecture'.

A major problem with early computers were the size of the components which made computers heavy. In 1950s, transistors were used instead of vacuum tubes which was 1/200 size of vacuum tubes. And so on, as the time passed, the computer became more powerful in terms of speed and memory and less in size. 

Some Generic Terms of a Computer

Processor : Processor is like the brain of the computer which organizes and carries out instructions.

In a PC, processor consists of one or more processors which are made up of silicon and other materials connected with many tiny electrical circuit. This microprocessor is connected into a circuit board which is also known as motherboard. Motherboard is a rectangular card that connects processor to other hardware.

Memory : Programs are loaded into and run from memory. Data used by program is also located into memory. The most common type of memory is RAM (Random Access Memory) which is a volatile memory i.e. it needs constant power supply. When we turn off the computer, everything in RAM will be erased. One of the factors which affects the computer speed is RAM. Computer memory is commonly described in bytes.

• 1 KB (Kilobyte) = 1024 Bytes
• 1 MB (Megabyte) = 1024 KB
• 1 GB (Gigabyte) = 1024 MB
•  1 TB (Terabyte) = 1024 GB

Input devices are the medium through which user can interact with computer i.e. feeding the input. In other words, input devices are those devices through which user inputs / gives commands to the computer. The most commonly used input device are mouse, keyboard, etc. 

Storage devices : Along with the processor, memory, input and output devices, computer also needs a place to keep programs and other stuffs. The purpose of storage device is to hold program and data files when computer is not using them. Some of the storage devices are non-volatile  whereas some are volatile. The storage devices capacity is much higher and less cheaper than the memory. Example : 1 GB RAM and 16 GB pen drive costs similar. Most commonly used storage devices are hard disk, floppy disk (rarely found nowadays), optical disks, etc.

Introduction to Computer

Computer is a machine that performs calculation and processes information with  great accuracy and speed. It can handle vast amount of information and solve complicated problems. The powerful computers can perform billions of calculation per second. The two principal characteristics of computer are :

1. It responds to specific set of instructions in a well-defined manner.
2. It can execute a prerecorded list of instruction (program).

Importance of Computer

With the help of computers, we can simplify difficult or time-consuming tasks. These tasks are :

1. Solving numerical problems :  With the help of computers, the numerical complicated problems can be completed easily. Such problems mainly occurs in scientific research or in huge mathematical calculations.
2. Storing and retrieving information : Information stored in a computer is called database. Computer nowadays are used to store small to huge amount of data. Example : country census data, etc.
3. Creating & Displaying documents and pictures : Computer can store huge no. of words in such a way that makes it easy to manipulate them. Example : Microsoft Words.

Characteristics of Computer

1. Word-length
2. Speed
3. Storage
4. Accuracy
5. Versatility
6. Automatic
7. Diligence 

Word-length : A computer operates on binary digits - '0' and '1'. A group of 8-bit is called a byte. The number of bits that a computer can process at any given time is called it's word-length. Word-length is computing power of computer. Commonly used word-length are : 8, 16, 32, 64. Example : When we say 64-bit Windows, it means that the word-length is 64.

Speed : Computers can calculate at very high speed. For example : super computers can operate at speed measured in nanoseconds or even in pico-seconds.

• 1 millisecond = 10^-3 seconds
• 1 microsecond = 10^-6 seconds
• 1 nanosecond = 10^-9 seconds
• 1 picosecond = 10^-12 seconds 

Storage : Computer have main memory and auxiliary memory which helps to store large amount of data. The factors that makes computer storage unique is not only storing power but also the fact that it can retrieve information that users wants in matter of seconds.

Accuracy : Computer can process a information in high accuracy. There is no chance of computer that it gives wrong output. As we know 'GIGO [Garbage In Garbage Out]', computer only displays wrong output when the input is wrong. Computer can perform complicated operations accurately and in high speed.

Versatility : Computer can run multiple tasks at a time. It has ability to process more than one information at a time. For example : a user can listen to music, create documents, upload/download, all at a same time.

Automatic : Computer is an automatic machine. A user just has to give a command to it and all the information are processed automatically by the machine. Such characteristic of computer is Automatic. For example : a user just gives a command to calculate something and the computer automatically calculates it and displays the result.

Diligence : Computer is never tired of doing same task again and again. Computer does not display bored or tired message of doing same task again and again. The same task can be processed infinite times by the computer, which is known as diligence.