Presentation Topic:

DRAM(Dynamic RAM) and its types.

What is RAM?• RAM is extra memory that provides space for

the Central Processing Unit (CPU) to read and write data.

• The more RAM your computer has, the less the CPU has to read data from your hard disk. This usually allows your computer to run faster since RAM is faster than the hard disk.

Cont..• Ram is volatile, meaning is does not retain data

when the electric power is turned off or fails, so if you turn of your computer, all memory stored in RAM is lost.

• When your computer is turned on again, the BIOS reads your operating system and related files from the hard disk and loads them back into RAM.

Types Of RAM:

SRAM(Static Random Access Memory)DRAM(Dynamic Random Access Memory)

Dynamic random-access memory (DRAM):- is a type of random-access memory that stores each bit of data in a separate capacitor within an integrated circuit. The capacitor can be either charged or discharged; these two states are taken to represent the two values of a bit, conventionally called 0 and 1. Since even "nonconducting" transistors always leak a small amount, the capacitors will slowly discharge, and the information eventually fades unless the capacitor charge is refreshed periodically. Because of this refresh requirement

Cont...• The main memory (the "RAM") in personal

computers is dynamic RAM (DRAM). It is the RAM in desktops, laptops and workstation computers as well as some of the RAM of video game consoles

Cont...

Types Of DRAM:-

There are four main types of RAM:• SDRAM•DDR•Rambus DRAM•DRAM

SDRAM(Synchronous DRAM)

• SDRAM started out running at 66 MHz, while older fast page mode DRAM and EDO max out at 50 MHz. SDRAM is able to scale to 133 MHz (PC133) officially, and unofficially up to 180MHz or higher. SDRAM is pretty much outdated now. More recent types of RAM, such as DDR and RDRAM, are required to get proper performance.

DDR(Double Data Rate SDRAM)• Double data rate SDRAM (DDR) was a later development

of SDRAM, used in PC memory beginning in 2000. Subsequent versions are numbered sequentially (DDR2, DDR3, etc.). DDR SDRAM internally performs double-width accesses at the clock rate, and uses a double data rate interface to transfer one half on each clock edge. DDR2 and DDR3 increased this factor to 4× and 8×, respectively, delivering 4-word and 8-word bursts over 2 and 4 clock cycles, respectively. The internal access rate is mostly unchanged (200 million per second for DDR-400, DDR2-800 and DDR3-1600 memory), but each access transfers more data

RDRAM(Rambus DRAM)• RDRAM is a serial memory technology that

arrived in three types, PC600, PC700, and PC800. PC800 RDRAM has double the maximum throughput of old PC100 SDRAM, but a higher latency. RDRAM designs with multiple channels, such as those in Pentium 4 motherboards, are currently at the top of the heap in memory throughput, especially when paired with PC1066 RDRAM memory.

DRAM memory module formats• Single In-line Memory Module, SIMM:

This type of DRAM or memory package holds up to eight nine RAM chips (8 in Macs and 9 in PCs where the 9th chip is used for parity checking). Another important factor is the bus width, which for SIMMS is 32 bits.

Cont.

• Dual In-line Memory Module, DIMM: With the increase in data bus width, DIMMs began to replace SIMMs as the predominant type of memory module. The main difference between a SIMM and a DIMM is that a DIMM has separate electrical contacts on each side of the module, while the contacts on a SIMM are on both sides are redundant. Standard SIMMs also have a 32-bit data bus, while standard DIMMs have a 64-bit data bus.

Cont.

• Rambus In-line Memory Module, RIMM: This type of DRAM memory package is essentially the same as a DIMM but is referred to as RIMMs because of their manufacturer and proprietary slot required

Major Manufacturers• Corsair Memory• Crucial Technology• EDGE Tech Corp• GEIL• G.Skill• Hynix• Infineon Technologies• Kingston Technologies • Micron Technology• PNY• OCZ Technology• Rambus• Samsung• SimpleTech