(Useful Term for Student of Computer Hardware Servicing NC II)
RAM (Random Access memory) basically known as the Computer Memory or Computer Data Storage. It allows keep information to be accessed in terribly nearly an equivalent quantity of your time for any storage location, thus information is accessed quickly in any random order.
There are two main types or forms of RAM; the SRAM (Static RAM) and DRAM (Dynamic RAM). SRAM is a form of RAM that is costlier to provide, however is usually quicker and needs less power than DRAM and, in trendy computers, is usually used as cache memory for the electronic equipment While DRAM stores a bit of data using a transistor and capacitor pair, which together comprise a memory cell. To read more about basics on RAM click here.
Different Versions of RAM
1. SDRAM (Synchronous Dynamic Random-Access Memory) - is dynamic random access memory (DRAM) that is synchronized with the system bus. Classic DRAM has an asynchronous interface, which means that it responds as quickly as possible to changes in control inputs. SDRAM has a synchronous interface, meaning that it waits for a clock signal before responding to control inputs and is therefore synchronized with the computer's system bus. The clock is used to drive an internal finite state machine that pipelines incoming commands. The data storage area is divided into several banks, allowing the chip to work on several memory access commands at a time, interleaved among the separate banks. This allows higher data access rates than an asynchronous DRAM.
Source: http://en.wikipedia.org/wiki/Synchronous_dynamic_random-access_memory
2. DDR SDRAM (Double Data Rate Synchronous Dynamic Random-Access Memory) - is a class of memory integrated circuits used in computers. Sometime referred to as DDR1 SDRAM. Compared to single data rate (SDR) SDRAM, the DDR SDRAM interface makes higher transfer rates possible by more strict control of the timing of the electrical data and clock signals. Implementations often have to use schemes such as phase-locked loops and self-calibration to reach the required timing accuracy.
Source: http://en.wikipedia.org/wiki/DDR_SDRAM
3. DDR2 SDRAM (Double Data Rate Synchronous Dynamic Random-Access Memory) - It supersedes the original DDR SDRAM specification and has itself been superseded by DDR3 SDRAM. DDR2 is neither forward nor backward compatible with either DDR or DDR3.
In addition to double pumping the data bus as in DDR SDRAM (transferring data on the rising and falling edges of the bus clock signal), DDR2 allows higher bus speed and requires lower power by running the internal clock at half the speed of the data bus. The two factors combine to require a total of four data transfers per internal clock cycle. With data being transferred 64 bits at a time, DDR2 SDRAM gives a transfer rate of (memory clock rate) × 2 (for bus clock multiplier) × 2 (for dual rate) × 64 (number of bits transferred) / 8 (number of bits/byte). Thus with a memory clock frequency of 100 MHz, DDR2 SDRAM gives a maximum transfer rate of 3200 MB/s.
Source: http://en.wikipedia.org/wiki/DDR2_SDRAM
4. DDR3 SDRAM (Double Data Rate Synchronous Dynamic Random-Access Memory) - is a modern kind of dynamic random access memory (DRAM) with a high bandwidth interface, and has been in use since 2007. DDR3 SDRAM is neither forward nor backward compatible with any earlier type of random access memory (RAM) due to different signaling voltages, timings, and other factors.
DDR3 is a DRAM interface specification. The actual DRAM arrays that store the data are similar to earlier types, with similar performance.
Source: http://en.wikipedia.org/wiki/DDR3_SDRAM
5. DDR4 SDRAM (Double Data Rate Synchronous Dynamic Random-Access Memory) - is a type of dynamic random-access memory (DRAM) with a high bandwidth interface expected to be released to market in 2012. It is one of several variants of DRAM which have been in use since the early 1970s. And is not compatible with any earlier type of random access memory (RAM) due to different signaling voltages, physical interface and other factors.
Source: http://en.wikipedia.org/wiki/DDR4_SDRAM
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