On the 18th day of A2Z Challenge 2019, I shall about A2Z of RAM (Random Access Memory) and ROM (Read Only Memory). In the world of computers, there are two kinds of primary memory (main memory) – RAM and ROM. RAM stores data as long as the computer is switched on. Once you switch off your computer, all the data is lost. This is why it is also known as volatile memory. ROM is non-volatile because its contents don’t get erased even when the computer is switched off.
A2Z of RAM
RAM is the internal memory that can be read from as well as written to. It is highly volatile because it can hold data temporarily. It requires a continuous flow of electricity. If the power supply is interrupted, data is lost. There are two types of RAM:
- SRAM: SRAM stands for Static RAM. It requires a constant power supply to store information. SRAM is commonly used in cache memory and Graphics card memory.
- DRAM: DRAM stands for Dynamic RAM. It stores data in a cell containing a capacitor and a transistor. These cells must be refreshed with electrical impulses at regular intervals. This allows it to keep the electrical charge and hold data as long as needed. It is slower, less expensive and consumes less power than SRAM.
A2Z of ROM
ROM is the internal memory that can only be read. Contents of ROM remains stored even if the computer is switched off. ROM can be further divided into three types:
- PROM: PROM stands for Programmable ROM. Once programmed, the data can’t be erased.
- EPROM: EPROM stands for Erasable Programmable ROM. Data can be erased by exposing the chip to ultra-violet light.
- EEPROM: EEPROM stands for Electrically Erasable Programmable ROM. This chip can be erased and reprogrammed with the help of electrical pulses.
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