Memory

Now we discuss about one of the most important parts of computers i.e memory. Computers generally possess several distinct types of memory, each of which "holds" or stores information for subsequent use. The vast majority of computer memory can be placed into one of two categories: primary memory and secondary memory


Primary memory, often called main memory, constitutes that device, or group of devices, that holds instructions and data for rapid and direct access by the computer's central processing unit (CPU). Primary memory is synonymous with random-access memory (RAM).

Modern RAM is made of semiconductor circuitry. RAM is a volatile form of information storage, meaning that when electrical power is terminated any data that it contains is lost. There are other semiconductor memory devices accessed by the CPU that are generally considered as being distinct from primary memory (i.e., different from RAM). These memory units include cache memory, read-only memory (ROM), and Programmable Read Only Memory (PROM) and EPROM (erasable programmable read-only memory

Secondary memory, also called auxiliary memory or mass storage, consists of devices not directly accessible by the CPU. Hard drives, floppy disks, tapes, and optical disks are widely used for secondary storage. First, most secondary storage devices are capable of containing much more information than is feasible for primary memory (hence the use of the term "mass storage" as a synonym for secondary memory). A second, and essential, feature of secondary memory is that it is non-volatile. This means that data is stored with or without electrical power being supplied to the device, as opposed to RAM, which can retain its data only so long as electrical power is present.

Like primary memory, many secondary memory devices are capable of storing information, as well as retrieving it. Magnetic technology devices (such as hard drives, floppy disks, and tape) have this read-write capability, as do magneto optical drives. However, some mass storage devices can only read data, as in the case of CD-ROM (Compact Disk-Read Only Memory) drives. CD-ROMs utilize 15 optical technology; however, newer optical technologies, such as CD-RW (compact disk-rewriteable), can both read and write information like magnetic storage devices.


The hard disk is the main, and usually largest, data storage device in a computer. The operating system, software titles and most other files are stored in the hard disk. Now let‘s have a Practice Session

Check Your Progress 1 

1. Find shortcut keys for the following: 

a) To Open Help. 

b) To repeat the last action performed. 

c) To save document 

d) To Bold the selected text 

 e) Change the text in Microsoft Word from uppercase to lowercase or capital letter at the beginning of every word. 

2. List use of following function keys: 

 F1, F2, F3, F4, F5, F7, F8, F12 

3. Type the following passage in MS-WORD 

Over the past few years the growth of the computer industry has been quiet remarkable and today it is the fastest growing industry in our economy. Nowadays, many schools are equipped with computers for educating their students. Thereby making computers an integral part of education system. Teachers and professors use computers for teaching, giving presentations, assessing various data banks, maintaining database of students, communication in the form of e mails or chat, browsing the Internet and Preparing students to have a competitive edge in the global job market. Computers have revolutionized the learning for students in a big way. They can watch various films on wild life, history, geography, science and encyclopedias with loud sound and excellent picture quality on Compact Disc‘ sorDVD‘s. 

(a) In this paragraph, there are few spelling errors. Try spelling check for this. Try to find and replace ‗loud‘ by ‗‗excellent‖. 

(b) Now save this paragraph with the name ‗computer‘ on your desktop.

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