Random Access Memory (RAM) is a type of computer memory. It derives its name from the fact that any piece of data stored on it can be accessed at any time. RAM however stores data for as long as the computer is switched on or is in use. It is the most common type of computer memory available today. The very first form of RAM was the magnetic core memory. It was in use till the introduction of static and dynamic integrated RAM. Prior to that, computers utilized vacuum tubes, ferromagnetic material coated drums, capacitors and so on to store, read and write data.

A memory chip is an integrated circuit which comprises of millions of transistors and capacitors. A single transistor and capacitor are coupled together to form a memory cell. The capacitor is responsible for saving the bit of data: that is either 0 or 1. The transistor acts as a toggle to enable the control circuitry to access the capacitor or alter its state.

What does RAM Stand For?

Classification of RAM

The two main classifications of RAM are:

Dynamic Random Access Memory (DRAM)

This type of RAM holds each bit of data in an individual capacitor in an integrated circuit. It is dynamic in the sense that the capacitor charge is repeatedly refreshed, to ensure the data remains intact. Implementation of DRAM is uncomplicated as only one transistor and capacitor are required for each bit of memory. DRAM is built in the following form factors:

  • Dual In-Line Package (DIP)
  • Single In-Line Pin Package (SIPP)
  • Single In-Line Memory Module (SIMM)
  • Dual In-Line Memory Module (DIMM)
  • Rambus In-Line Memory Module (RIMM)
  • Small Outline DIMM (SO-DIMM)
  • Small Outline RIMM (SO-RIMM)

Static Random Access Memory (SRAM)

This type of RAM is static in nature, as it does not have to be refreshed at regular intervals. It uses bistable latching circuitry to store each bit of data. Each bit of data is stored on four transistors. Two transistors act as the storage cell which represents 0 and 1. The other two transistors act as access transistors to manage access to the storage cell throughout the read and write processes. SRAM is mainly used as memory cache, due its high cost of implementation. It is also used for hard disk buffers, router buffers, CDROM and CDRW buffers. SRAM is built in the following form factors:

  • Non Volatile SRAM
  • Asynchronous SRAM
  • Synchronous SRAM