Ram Harddisk keyboard & Mouse connects to a computer

How keyboard connects to a computer?

Computer Keyboard can connect with a computer through a cable or signal (wireless connection). Until recently, a keyboard used to connect with the standard PS/2 type or Serial.

Now, this trend has changed and the connection is replaced by USB (universal serial bus) and wireless connectors. Most modern PCs (motherboards) even don't have PS/2 connectors, only USB.

Since, there is no cable connection with main PC, wireless keyboard gets power from battery or a/c power connection. This is the side effect of wireless keyboards; you often have to change battery.

Mouse

The mouse is a small device used to point to a particular place on the screen and select in order to perform one or more actions. It can be used to select menu commands, size windows, start programs etc. The most conventional kind of mouse has two buttons on top: the left one being used most frequently.

Mouse buttons

Primary button / left button for left click

Secondary button / right button for right click

Scroll wheel for moving page up or down

Mouse Actions

Pointing    : Point the object

Left Click: Used to select an item.

Double Click: Used to start a program or open a file. 

Right Click: Usually used to display a set of commands.

Drag and Drop: It allows you to select and move an item from one location to another. To achieve this place the cursor over an item on the screen, click the left mouse button and while holding the button down move the cursor to where you want to place the item, and then release it.

How Mouse is connected to PC

Mouse is connected to pc similarly as keyboard. It can be connected with either PS/2 connectors or USB. The connections can be through a cable or wirelessly as well.

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 optical technology; however, newer optical technologies, such as CD-RW (compact disk-rewriteable), can both read and write information like magnetic storage devices.

Hard Disk

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.