1. Random Access Memory (RAM):
The main memory RAM size varies from 16 MB, 32 MB, 64 MB to 8 GB.
Features:
- Fast Memo; EXpensive memory, small size memory, Volatile in nature i.e., data stored on it completely erased as and when the computer is switched ***.
*2. Different types of RAM’ are:
a. Dynamic RAM** (DRAM) – is the most common type of memory and is small and cheap but slow. It pair of transistors and capacitors makes the memory cell where transistors are arranged in matrix form and capacitors are used to hold 0 and 1 bits. DRAM must by refreshed continuously to retain data in memory with the help of refresher circuit.
b. Static RAM ( SRAM) -normally uses 4 to 6 transistors to form the memory cell and takes more space on a chip. No capacitors are used and refreshing is not required. It is much faster than DRAM therefore used in cache memory.
c. Synchronous Dynamic RAM ( SDRAM) – A special type of DRAM where synchronized to the system clock of the CPU thereby reduces CPU waiting time for data.
d. Double Data Rate RAM (DDRRAM) – is the same as SDRAM except data transfer rate is double the rate of SDRAM.
3. Read-Only Memory (ROM):
These are non-volatile fixed size memory usually supplied by manufacturers of motherboards.
Types of ROM
- PROM – Programmable ROM
- EPROM – Erasable Programmable ROM
- EEPROM – Electrically Erasable Programmable ROM
