Generic DDR-266 Memory in the 184pin DIMM form / Image Source: Wikipedia
We’ve been telling you that our boring products featured in this series of posts are useful, but still boring. Well, none of them probably do justice with this phrase more than this week’s boring product, Ram.
Boring but Essential
Ram (Random Access Memory) is the most important component of a computer after the processor and it is in fact the most important piece of hardware when it comes to multitasking (that we all love to do).
Similar to a microprocessor, a memory chip is an integrated circuit (IC) made of millions of transistors and capacitors. In the most common form of computer memory, dynamic random access memory (DRAM), a transistor and a capacitor are paired to create a memory cell, which represents a single bit of data. The capacitor holds the bit of information — a 0 or a 1. The transistor acts as a switch that lets the control circuitry on the memory chip read the capacitor or change its state.
Types of Ram
Modern types of writable Ram generally store a bit of data in either the state of a flip-flop, as in SRAM (static Ram), or as a charge in a capacitor (or transistor gate), as in DRAM, EPROM, EEPROM and Flash.
There have been further enhancements in the DRAM such as synchronous dynamic random access memory (SDRAM) and DDR SDRAM, which is used in almost all modern computers.
DDR SDRAM
Compared to the preceding single data rate (SDR) SDRAM, the Double Data Rate synchronous dynamic random access memory (DDR SDRAM) interface makes higher transfer rates possible by more strict control of the timing of the electrical data and clock signals. With a bus frequency of 100 MHz, DDR SDRAM gives a maximum transfer rate of 1600 MB/sec.
DDR SDRAM modules for desktop computers, commonly called DIMMs, have 184 pins (as opposed to 168 pins on SDRAM, or 240 pins on DDR2 SDRAM), and can be differentiated from SDRAM DIMMs by the number of notches (DDR SDRAM has one, SDRAM has two). DDR SDRAM for notebook computers, SO-DIMMs, have 200 pins, which is the same number of pins as DDR2 SO-DIMMs.
Types of DDR
DDR (DDR1) has been superseded by DDR2 SDRAM, which has some modifications to allow a higher clock frequency, but operates on the same principle as DDR. DDR3 SDRAM is a new standard that offers even higher performance and new features.
DDR’s pre-fetch buffer depth is 2 bits, while DDR2 uses 4 bits. The effective clock rates of DDR2 are higher than for DDR.
Data Rate of DDR1, DDR2 and DDR3
With a bus frequency of 100 MHz, DDR SDRAM gives a maximum transfer rate of 1600 MB/sec, DDR2 SDRAM gives a maximum transfer rate of 3200 MB/sec and DDR3 SDRAM gives a maximum transfer rate of 6400 MB/sec.
MDDR
MDDR is an acronym that some enterprises use for Mobile DDR SDRAM, a type of memory used in some portable electronic devices, like mobile phones, handhelds, and digital audio players. While standard DDR SDRAM operates at a voltage of 2.5 V, MDDR operates at voltage of 1.8 V, which allows reduced power consumption.
With rapid development in processor chips, modern processors demand high capacity and faster memory components. Although Ram is an expensive component, the first thing you should add to your shopping list when you plan to upgrade your computer should be Ram as more memory means more multitasking and a faster response time.
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