CBSE Class 11: Computer System Organization 3

Secondary Memory role in Computer Systems and Organization

Secondary memory is also known as auxiliary memory. It stores data permanently. It has a larger storage capacity than primary memory. Data written on secondary memory must be brought up on to primary memory before use.


Storage Devices

Hard Disk

• It has magnetic storage to store data, retrieve data
• It has rotating platters coated with magnetic material
• These platters are paired with magnetic heads
• Magnetic heads are arranged on a moving actuator arm that read and write data to platter surfaces
• It is a non-volatile memory
• It has a large storage capacity compared to other secondary storage devices




IO and Battery are two devices which are performing the tasks of supplying input and output power in Computer Systems and Organization.

• It pronounced as “eye-oh”
• Refers to a program, operation or devices that transfer data to or from a computer and to or from a peripheral device
• The transfer is input for one device and output for another device
• Example: Writable CD



• Supplies power to a device that allows operating computer without power
• It runs computers several hours with power backup
• They are rechargeable components
• Three types of batteries are used in computers i. Backup Battery: These batteries hold computer settings such as date and time, other devices. Ex. CMOS Battery
• Main Battery: Main batteries refer to an alternate source of energy when the computer is not connected with the wall outlet Ex. Laptop Battery
• Bridge Battery: It allows us to remove the main battery and replace it without having to turn off the computer.