What is RAM?
. Random Access Memory is a type of computer data storage.
. It provides space for your computer to read and write data to be accessed by the CPU (central processing unit).
. If you add more RAM to your computer, it reduces time for CPU to read data from hard disk.
. RAM is volatile, so data stored in RAM stays there only as long as your computer is running.
. As soon as you turn the computer off, the data stored in RAM disappears.
. RAM comes in variety of capacities (MB-GHz), speed (MHz-GHz) and architectures.
. Many devices like desktops, laptops, mobiles, tablets etc make use of RAM.
. If you add more RAM to your computer, it reduces time for CPU to read data from hard disk.
. RAM is volatile, so data stored in RAM stays there only as long as your computer is running.
. As soon as you turn the computer off, the data stored in RAM disappears.
. RAM comes in variety of capacities (MB-GHz), speed (MHz-GHz) and architectures.
. Many devices like desktops, laptops, mobiles, tablets etc make use of RAM.
Types of RAM:
. Static RAM: Used in routers, printers, digital cameras
. Dynamic RAM: Used in system memory, video graphics memory.
. Synchronous Dynamic RAM: Used in computer memory and video game consoles.
. Single Data Rate Synchronous Dynamic RAM: Used in computer memory and video game consoles.
. Double Data Rate Synchronous Dynamic RAM: Used in computers.
. Graphics Double Data Rate Synchronous Dynamic RAM: Used in video graphics, tablets.
What is ROM?
. Read Only Memory is a type of storage medium which permanently stores data.
. Contains programming need to start a PC and computer to boot up.
. Data in ROM is not lost even power is off.
. It is found as chips on the motherboard and it mainly stores firmware data.
. Example is BIOS which stores program to turn on the computer using ROM.
. ROM is used not only in computer, but also in other types of devices like washing machine, microwave oven etc.
Types of ROM:
. Mask ROM: Data is written during manufacturing of chip.
. Programmable ROM (PROM): Data is written after creation of chip. It is non changable.
. Erasable PROM (EPROM): Data on this chip can be erased using uv light exposure. It takes 40 minutes to erase data.
. Electrical EPROM (EEPROM): Data on this chip is erased using electric current. It takes 4-10 milliseconds to erase and program data.
RAM Vs ROM:
| Difference | RAM | ROM |
|---|---|---|
| Volatality | Volatile memory. When computer is switched off, data is lost. | Non-Volatile memory. When computer is switched off, data is retained. |
| Function | Stores current active program and its data. | Stores certain fixed routines like boot-up etc. |
| Data | Not stored permanently but it can be altered number of times. | Data in ROM is stored permanently, it can be altered in limited times. |
| Accessibility with CPU | CPU can directly access the data stored in it. | CPU cannot directly access data from ROM. Inorder to access, first data is copied into RAM and accessed. |
| Speed | It is high speed memory. | It is slower than RAM. |
| Size and Capacity | Large size with higher capacity. | Small size with less capacity. |
| Usage | Primary memory, CPU Cache. | Firmware start up programs like BIOS, electronic devices to start up. |
| Cost | It is costlier compared to ROM. | It is cheaper compared to RAM. |