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Basics of Computers Primary Memory

Basics of Computers Primary Memory

Memory is needed for storing data and instructions in computers. Memory is arranged mechanically as a vast number of cells, capable of storing one bit each. We are logically arranged as groups of bits called terms, which are given an address. Such memory handles are used to view data and instructions.

It may be seen that computer memory is arranged in a hierarchical manner where memory with the quickest access speeds and the highest cost is at the peak, and those with the lowest speeds and thus the lowest cost are at the bottom. Memory is of two types depending on this definition-primary and secondary. This is where we'll look in detail at primary memory.

Primary memory's key features the distinguish it from secondary memory are −

  • The processor gets full access to it
  • This is the speediest usable memory
  • Every single word is stored as well as
  • It is unpredictable, indicating that its contents will be lost until power is turned off


RAM stands for Random Access Memory. The processor explicitly accesses all memory addresses, irrespective of the word length, allowing storing and retrieval fast. RAM is the best usable memory, and also the most expensive. Those two variables indicate RAM is usable in very low quantities of up to 1 GB. RAM is volatile, but my being of one of these 2 types

DRAM (Dynamic RAM)

Can memory cell in a DRAM consists of one transistor and one condenser to store a bit of data. This unit, though, begins to lose its charge, and thus stored data in less than a thousandth of a second. Then it has to be updated a thousand times a second, which eats up processor time. Nonetheless, one DRAM may have a huge number of cells due to the limited size of each cell


Every cell in SRAM consists of a flip flop which stores a bit. This holds the bit when the power supply is on and can not be renewed like DRAM does. This also has shorter read-write cycles than DRAM. SRAM is used in specialized systems.


ROM stands for Read Only Memory. As the name suggests, ROM can only be read by the processor. Unable to insert fresh data into ROM. In the development process itself, the data to be processed in ROM is written down. These include details which need not be changed, such as a computer's boot sequence or algorithmic tables for mathematical applications. ROM is slower and thus less costly than RAM.

Even when power is turned off, it maintains its data, i.e. it is non-volatile ROMs can not be modified like the way RAM can be, however, technologies are accessible to customize these ROMs –

PROM (Programmable ROM)

PROM may be configured using a PROM programmer or PROM burner, a special hardware device.

EPROM (Erasable Programmable ROM)

EPROM may be removed with different electrical signals or UV rays and then configured. EPROMs which can be deleted with UV radiation are called UVEPROM, and those which can be removed with electrical signals are called EEPROM. But it is simpler and better to treat electrical signals than UV rays.

Cache Memory

Short piece of high-speed transient memory accessible to the processor is called cache memory for quick processing. The cache may be a dedicated main memory component, another CPU core, or an isolated high-speed storage unit. Cache processing is constructed of SRAMs with rapid pace. Caching is also the method of storing such data and instructions in the cache memory for quicker entry.

Whenever the processor needs some piece of data or commands, it searches the cache first. If it is inaccessible there, then the main memory and eventually secondary memory is reached.