You have heard a lot of memory such as RAM memory, ROM memory, HDD memory or USB memory is also memory, etc. So how are they classified? Let’s find out together.
1. Types of computer memory
Computer memory can be divided into: primary memory (ROM and RAM) and secondary memory (other storage devices).
It is also called internal memory (ROM and RAM) and external memory (other storage devices).
2. ROM memory and types of ROM memory
2.1. ROM memory (Read Only Memory)
ROM is non-volatile memory, stored data is not lost when the computer is turned off. It is used to store BIOS program.
The BIOS program stores the specifications of the hardware components, startup program of computer is pre-loaded by the manufacturer.
How to recognize ROM?
- Shape: rectangle, square
- Manufacturer: usually AMI, Phoenix-Award, Winbond
- How to connect: solder or mount to socket
2.2. Types of ROM memory
ROM memory includes the following types:
PROM (Programmable ROM)
PROM is read-only and can be programmed (BIOS loaded) but only once. This chip is programmed once and the data on the chip cannot be erased. PROM was invented in 1956 by Wen Tsing Chow.
EPROM (Erasable Programmable ROM)
EPROM stored data and these data can be erased with ultraviolet light. It was invented in 1971 by Dov Frohman.
EEPROM (Electrically Erasable Programmable ROM)
EEPROM stored data can be electrically erased and then rewritten without having to be removed from the computer.
In 1972, EEPROM was manufactured by the National Research Institute of Japan.
Flash memory
Flash memory was invented by Fujio Masuoka at Toshiba in 1972. This memory is a type of EEPROM with high speed and large capacity. It works on NOR and NAND logic gates.
