What is an RRAM transistor

DRAM - Dynamic RAM

DRAM is the simplest, slowest, and cheapest type of memory there is. DRAM chips are produced in gigantic quantities around the world. Mostly in the SDRAM variant. For a long time, only this one type of memory was known in the computer sector for the working memory or main memory.

DRAM memory cell

A DRAM memory cell consists of a transistor and a capacitor (1T1C), which is the actual storage element. A bit is stored in a DRAM memory cell by the charge on the capacitor.
Reading and writing takes place via the transistor, which works as a switch and isolates the charge on the capacitor or releases it onto the bit line. The transistor is addressed via the word line.
The disadvantage of this type of memory is that the capacitor discharges due to leakage currents and the memory state has to be updated again and again (refresh). In order to maintain the charge in the capacitor, a refresh is necessary several thousand times a second.

Properties of DRAM

  • Data storage in a capacitor
  • needs refresh
  • low energy consumption
  • Use as main memory or graphics memory

Memory access

A memory chip consists of many memory cells that are arranged in a matrix. These memory cells are addressed via rows and columns.
A 16 Mbit memory chip has 4,096 x 4,096 bits (16.8 million memory cells). To be able to address all of these, 12 rows and 12 columns are required. This makes it possible to 4.096 (212) To be able to map addresses or states.
However, this 16 Mbit memory chip does not have far more than 24 connections. For reasons of space saving and manufacturing costs, fewer are used. In order to still be able to reach the 4,096 addresses, the technique of multiplexing is used. The same lines are used to transmit row and column addresses.
When addressing a memory cell, first the row address (row access strobe, RAS) and then the column address (column access strobe, CAS) are transmitted.
The external speed of a memory depends, among other things, on how quickly you can switch between RAS and CAS.

The addressing of the memory can be simplified by arranging the RAM memory cells in a matrix or table. After each clock cycle, a switch is made between specifying the column address (RAS, Row Address Signal) and the row address (CAS, Column Address Signal). In the Fast-Page-Mode this RAS / CAS method is optimized and allows access to the data up to three times faster than with conventional DRAM. The creation of the same line address is saved during continuous memory access. It is sufficient to specify the row address once and the respective column address. Access is much faster.

SDRAM - Synchronous DRAM

The property of SDRAM is that its read and write access is based on the system clock. That means it works synchronously with the memory bus. This allows the control of the memory to be significantly simplified and accelerated. Normal DRAM works asynchronously.

Overview: semiconductor memory

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Everything you need to know about computer technology.

Computer technology primer

The computer technology primer is a book about the basics of computer technology, processor technology, semiconductor memory, interfaces, data storage devices, drives and important hardware components.

I want that!