MEMORY

A memory is a temporary storage that computers uses to hold data and instructions.

One of the most important storage devices is random access memory(RAM), that is the

 fastest way in which data can get to the processor. Random access memory (RAM) is the

temporary storage for data and programs that are being accessed by the CPU.

Non volatile / volatile

• A volatile memory, lose its data when the computer is powered off.

• On the other hand, a Non Volatile memory that does not lose its data when switched off.

Different types:

RAM: 

Is one of the most important storage devices, is a volatile memory, that stores data and programs that are being accessed by the CPU. RAM is a volatile memory.

ROM:

Read-only memory (ROM)  contains basic instructions for booting the computer and loading the operating system. ROM, on the other hand, is a Non Volatile memory

CACHE:

Is fast and expensive as well. It is located inside the processor. The main function is to save common instructions.

The different types of RAM are:

Dynamic Random Access Memory (DRAM) is a memory chip that is used as main memory. DRAM must be constantly refreshed with pulses of electricity in order to maintain the data stored within a chip.

Static Random Access Memory (SRAM) is a memory chip that is used as cache memory. SRAM is much faster than DRAM and does not have to be refreshed as often.

Fast Page Mode DRAM (FPM Memory) is memory that supports paging. Paging enables faster access to the data than regular DRAM. Most 486 and Pentium systems from 1995 and earlier use FPM memory.

Extended Data Out RAM (EDO Memory) is memory that overlaps consecutive data accesses. This speeds up the access time to retrieve data from memory, because the CPU does not have to wait fro one data access cycle to end before another data access cycle begins.

Synchronous DRAM (SDRAM) is DRAM that operates in synchronization with the memory bus. The memory bus is the data path between the CPU and the main memory.

Double Data Rate SDRAM (DDR SDRAM) is memory that transfers data twice as fast a SDRAM. DDR SDRAM increases performance by transferring data twice per cycle.

Double Data Rate 2 SDRAM (DDR2 SDRAM) is faster than DDR SDRAM memory. DDR2 SDRAM improves performance over DDR SDRAM by decreasing noise and crosstalk between the signal wires.

RAMBus DRAM (RDRAM) is a memory chip that was developed to communicate at very high rates of speed. RDRAM chips are not commonly used.

Early computers had RAM installed on the motherboard as individual chips. The individual memory chips, called dual inline package (DIP) chips, were difficult to install and often became loose on the motherboard. To solve this problem, designers soldered the memory chips on a special circuit board called a memory module. The different types of memory modules are:

Dual Inline Package (DIP) is an individual memory chip. A DIP had dual rows of pins used to attach it to the motherboard.

Single Inline Memory Module (SIMM) is a small circuit board that holds several memory chips. SIMMs have 30-pin and 72-pin configurations.

Dual Inline Memory Module (DIMM) is a circuit board that holds SDRAM, DDR SDRAM, and DDR2 SDRAM chips. There are 168-pin SDRAM DIMMs, 184-pin DDR DIMMs, and 240-pin DDR2 DIMMs.