Memory

Random Access Memory(RAM)

Random Access Memory or RAM is a general purpose memory. The purpose of RAM is to hold user programs run time data. This is a non-volatile memory i.e., it loses the data on power off or on reset action. Most of the microcontrollers comes with some amount of RAM, depending upon the peripherals incorporated and the end-application of the microcontroller.

Read Only Memory(ROM)
Read Only Memory or ROM is used to hold the user program. The ROM memory are also useful to hold the users fixed data. This is volatile memory i.e., it can retain the user data even in power shutdown or reset action. The content of ROM can not be changed once written. ROMs are the cost effective solution to generate number of copies of users final program.

Programmable Read Only Memory(PROM)
Programmable Read Only Memory or PROM is type of ROM memory. This is also a volatile memory. The PPROM can be programmed using suitable programming devices. PROM is used to store the user program and the content of it can not be change once written. This memory is useful for lower rate of production.

Erasable Programmable Read Only Memory(EPROM)
Erasable Programmable Read Only Memory or EPROM is also a type of ROM memory. This is a volatile memory. This memory can be erased by focusing Ultra Violate(UV) light on a small glass window available at the top of chip. To program or write EROM suitable programming devices are available. EPROM can be erased and reused to store the user program, till the satisfaction of user. EPROMs are also available with OTP(One Time Programmable) versions.

Electrically Erasable Programmable Read Only Memory(EEPROM)

Electrically Erasable Programmable Read Only Memory or EEPROM is a nonvolatile Read Only Memory. This memory can be used for many purposes depending on the user application like to save fixed information, System Default Configurations, System Default Values or User Data and more. EEPROM can programmed using Memory Programmer’s or using a Microcontroller program. EEPROM are comparatively costly and slow in operation. EEPROMs are available with serial and parallel communication bus.

Flash
Flash is a nonvolatile and reprogrammable Read Only memory. Flash has become very popular in microcontroller applications and widely in many microcontrollers. Flash is used mostly to store the user program, but it can also be use to save the useful data. Suitable Memory Programmers are available to erase and write Flash memory.