Primary Storage

Primary storage is volatile, usually has small capacities and is relatively much faster than secondary storage.

Primary Memory Includes:

• • RAM

  • ROM (see ROM)

  • Cache Memory (See CPU)

  • Registers (See CPU)

Random access memory (RAM)

The name given to this group of primary storage hardware is in fact incorrect. It should more correctly have been called non sequential access memory,(perhaps NSAM is a silly acronym and that is why they gave it an easier, but incorrect name) There is nothing at all random about the way in which the RAM is accessed. It was developed in a time when data was being stored on tapes and the issue with a tape is that it is long and thin and if you want a piece of data that is at the end of the tape you have to wind the tape all the way to the end in order to get it... which takes time. Electronic storage was developed where any piece of data stored at any place in the circuit could be accessed in the same amount of time... no need for winding the tape. This ability to get to any data at any time was why it was named "RANDOM ACCESS".... and the name stuck.

There are several different types of RAM, The first type of RAM that was used for System memory was magnetic core memory, it was very bulky and not very reliable.

Dynamic RAM

Dynamic RAM is made of capacitors.[stores a tiny charge to represent a one or no charge to represent a zero]

Dynamic RAM is cheap, compact and works well.  it is used at primary memory in the computer system because large volumes of RAM [several gigabytes] relatively cheaply.  The frequency at which modern dynamic RAM operates is in excess of 2Ghz which means that the data transfer rate between the RAM and the CPU is significantly better than in recent history where this bottleneck has persisted for 20 years.

Dynamic RAM needs to be refreshed often as the capacitors lose their charge after a fraction of a second. The refreshing of the data in the RAM takes time and that slows the computer down.

Static RAM

Static RAM is made from transistors.  [Switches] These switches can be set to on(one) or off(zero) and while the hardware has electric power the transistors [switches] will stay in that position, effectively keeping the data.  

Static RAM has a much shorter access time than dynamic RAM because it does not have to be refreshed and more logically it is made of "the same stuff" as a CPU so it can operate at exactly the same frequency as the CPU.  

The disadvantage of static RAM is that it is far more bulky than dynamic RAM so it takes up a lot more space to have 1Gb or Static RAM, and Static RAM is far more expensive so it is not practical to place 8Gb or Static RAM on a motherboard, it would be too expensive and take up so much space that it would be ineffective.

Static RAM is used to create cache memory, small amounts of it are placed very close to the CPU and help to buffer the data coming out and going into the CPU.  Hardware manufacturers and software developers have tried to use Static RAM to compensate for the inefficiencies associated with Dynamic RAM.

The aim of cache memory [made of static RAM] is to reduce the number of clock cycles that are wasted while the CPU waits for the the front side bus to store or retrieve data from the system primary memory [made of Dynamic RAM]

Double Data Rate (DDR)

It is an advanced version of SDRAM, a type of computer memory. DDR-SDRAM, sometimes called "SDRAM II," can transfer data twice as fast as regular SDRAM chips. This is because DDR memory can send and receive signals twice per clock cycle. The efficient operation of DDR-SDRAM makes the memory great for notebook computers since it uses up less power.  DDR2 and DDR3 are more modern faster kinds of DDR memory.

Dual Channel Memory

RAM can be separated into two banks.  Both banks can be read from and written to at the same time effectively doubling the speed of RAM.