Tom Luxsox Coins

Quarter Ddr

DDR SDRAM And DDR2 SDRAM - A Comparison

The DDR SDRAM or the Double Data Rate synchronous dynamic random access memory can be defined as a ‘class of memory integrated circuits' that are commonly being used in computers. The DDR SDRAM interface definitely makes higher transfer rates achievable as compared to SDR (Single data rate) SDRAM. This is possible through a stricter control of the electrical data and the clock signal timing. In order to reach the timing accuracy, phase locked loops and self calibration schemes have to be used. For lowering of the clock frequency the interface uses a technique called ‘double pumping'. Double pumping is the transferring of data both on the rising and falling edges of the clock signal. By keeping the clock frequency down, the signal integrity requirements on the circuit board that connects memory to controller, get reduced.

The DDR RAM is termed as ‘double data rate' as it is able to achieve, with a certain clock frequency, almost twice the bandwidth of a ‘single data rate' the (SDR) SDRAM, which is running at the same clock frequency. On the transfer of data of 64 bits at one time, the DDR SDRAM gives the following transfer rate:

• (memory bus clock rate) x 2(for dual rate) x 64(number of bits transferred)/8(number of bits/byte)
• Thus the DDR SDRAM is able to give a maximum transfer rate of 1600 MB/s with a bus frequency of 100 Mhz.
• The DDR SDRAM got superseded by a newer DDR2 SDRAM. Therefore it is sometimes also referred to a DDR1 SDRAM.

 

The DDR2 SDRAM has an additional feature in addition to double pumping of data bus as in DDR SDRAM. It allows higher bus speed and it needs lower power. This is possible by running the internal clock at one quarter of the speed of the data bus. Both these factors put together, require a total of 4 data transfers per internal clock.

The DDR2 SDRAM is able to give the following transfer rate, when data is transferred at 64 bits at a time:

• (memory clock rate) x 2(for bus clock multiplier) x 2 (for dual rate) x 64(number of bits Transferred)/8(number of bits/byte).
• Thus DDR2 SDRAM can give a maximum transfer rate of 3200MB/s with a memory clock frequency of 100 MHz. Compared to the best rated DDR memory modules, the best rated DDR2 memory modules work atleast twice as fast.

In both DDR and DDR2 the memory is stored in memory cells that get activated with a clock signal that aligns its operation with an external data bus. In both, the ‘double pumping' technique takes place i.e the I/O buffer transfers data on the rising as well as the falling edge of the clock. The principal difference between the DDR and DDR2 is that in case of DDR2 the memory cells are clocked at one quarter the rate of the bus rather than half. This needs a 4 bit deep prefetch queue. DDR2 is able to operate most efficiently at twice the bus speed of DDR, and that too without changing the memory cells. The electrical improvements, prefetch buffers, on-die termination and off-chip drivers boost up the bus frequency. But latency is greatly increased. The prefetch buffer is 4 bits deep for DDR2, 2 bits deep for DDR and 8 bits deep for DDR3. Latencies are between 2 and 3 bus cycles for DDR SDRAM and between 4 and 6 cycles for DDR2. Hence to achieve the same latency, the DDR2 memory needs to be operated at twice the data rate.

The DDR2 chips are packaged in a BGA package that is more expensive and more difficult to assemble, leading to an increased bandwidth cost. As the manufacturing process is improved because of die shrinkage, power savings are being achieved.

About the Author

The author is an expert writer in the field of the technology. Presently writing on various topics related to computer hardware and peripherals like computer RAM; sdr, ddr sdram, ddr2 sdram, ddr3 sdram and other computer memory products.

No Quarter $7.49 No Quarter

Quarter $87.62 High Quality Content by WIKIPEDIA articles Quarter is one fourth,, or 25. Quarter may also refer to: Quarter (academic), a division of an academic year lasting from 8 to 12 weeks Quarter (United States coin), valued at onefourth of a U.S. dollar Quarter (Canadian coin), valued at onefourth of a Canadian dollar Quarter day, in British and Irish tradition, one of four dates in each year on which rents, etc. were due Quartering (heraldry), joining several coats of arms on one shield partitioned in four Quarters, a drinking game Academic quarter, term used by universities in various European countries for the 15 minutes between the defined start time for a lecture and the actual time it will start Fiscal quarter, three months of a fiscal year An imperial measure of weight, equal to 28 pounds. (See hundredweight) Author: Surhone, Lambert M./ Timpledon, Miriam T./ Marseken, Susan F. Binding Type: Paperback Number of Pages: 132 Publication Date: 2010/06/12 Language: English Dimensions: 5.98 x 9.01 x 0.30 inches

1GB DDR -TOUGHBOOK 51 $214.99 1GB DDR -TOUGHBOOK 51

Das Beste Der Ddr $9.99 Das Beste Der Ddr

Jewellery Quarter $9.49 Jewellery Quarter

Cisco 512MB DDR SDRAM Memory Module 512MB DDR SDRAM MEM2811256U768D $2422.25 Cisco 512MB DDR SDRAM Memory Module 512MB DDR SDRAM MEM2811256U768D

Avant / 512MB 400MHz DDR / DDR40064X64 $27.58 Avant - 512MB 400MHz DDR - DDR40064X64

256MB DDR PC2100 HP DC164A $92.75 256MB DDR PC2100 HP DC164A

Crucial 512MB DDR SODIMM CT6464X335X $37.48 Crucial 512MB DDR SODIMM CT6464X335X

256MB DDR Dimm 100pin Q262760002 $41.16 256MB DDR Dimm 100pin Q262760002

512MB DDR 184pin ECC MEM3800256U768D $2422.25 512MB DDR 184pin ECC MEM3800256U768D

Cisco Memory 512MB DDR MEM2821512D= $2422.25 Cisco Memory 512MB DDR MEM2821512D=

Cisco Memory 256MB DDR MEM2811256D= $1387.25 Cisco Memory 256MB DDR MEM2811256D=

Cisco Memory 512MB DDR MEM2811512D= $2422.25 Cisco Memory 512MB DDR MEM2811512D=

256MB Cisco Memory DDR MEM2821256D= $1387.25 256MB Cisco Memory DDR MEM2821256D=

Cisco Memory 256MB DDR MEM2851512D= $2422.25 Cisco Memory 256MB DDR MEM2851512D=

1GB PC-3200 DDR For Optima D1GBPC32OPT $33.31 1GB PC-3200 DDR For Optima D1GBPC32OPT

128MB DDR PC-3200 400MHz 184pin $4.97 128MB DDR PC-3200 400MHz 184pin

2GB DDR (1x2GB) PC-3200 73P4793 $152.25 2GB DDR (1x2GB) PC-3200 73P4793

256MB DDR Module Edge Q2627APE $28.1 256MB DDR Module Edge Q2627APE

Wii Ddr Hottest Party 2 $20.99 WII DDR HOTTEST PARTY 2

Das Beste Der Ddr (Uk) $9.99 Das Beste Der Ddr (Uk)

Ddr: Dragon Destiny Radio (Japan) $79.99 Ddr: Dragon Destiny Radio (Japan)

In the Quarter, $28.84 This is a reproduction of a book published before 1923. This book may have occasional imperfections such as missing or blurred pages, poor pictures, errant marks, etc. that were either part of the original artifact, or were introduced by the scanning process. We believe this work is culturally important, and despite the imperfections, have elected to bring it back into print as part of our continuing commitment to the preservation of printed works worldwide. We appreciate your understanding of the imperfections in the preservation process, and hope you enjoy this valuable book.

In the Quarter $44.28 One evening in May, 1888, the Caf des coles was even more crowded and more noisy than usual. The marbletopped tables were wet with beer and the din was appalling. Someone shouted to make himself heard. Any more news from the Salon? Yes, said Elliott, Thaxtons in with a number three. Rhodes is out and takes it hard. Cliffords out too, and takes it Author: Chambers, Robert W./ 1st World Library Binding Type: Hardcover Number of Pages: 260 Publication Date: 2006/02/01 Language: English Dimensions: 8.50 x 5.50 x 0.75 inches

In The Quarter $13.6 No Synopsis Available