Presentation on DDR RAMs.

1. DDR - SDRAMs
MADE BY : PRANKIT MISHRA (141CC00007)
UNDER THE GUIDANCE OF : MR. NISHANT MATHUR(FACULTY INCHARGE)
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2. Content
•RAM
•CLASSIFICATION OF DRAMS
•SDRAM
•TYPES OF SDRAM
•DDR 1
•DDR 2
•DDR 3
•DDR 4
•COMPARISION BETWEEN SDRAM
•REFERENCES
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3. RAM
•RAM is an acronym for random access memory, a type of computer memory that can
be accessed randomly; that is, any byte of memory can be accessed without touching the
preceding bytes.
•RAM is the most common type of memory found in computers and laptops.
•The two types of RAM differ in the technology they use to hold data, with DRAM being the more
common type. In terms of speed, SRAM is faster.
•DRAM needs to be refreshed thousands of times per second while SRAM does not need to be
refreshed, which is what makes it faster than DRAM.
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4. ClassificationOf DRAMs
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5. SDRAM
•It stands for Synchronous Dynamic Random Access Memory. "Synchronous" tells about the
behaviour of the DRAM type.
•In late 1996, SDRAM began to appear in systems.
•Unlike previous technologies, SDRAM is designed to synchronize itself with the timing of the
CPU. This enables the memory controller to know the exact clock cycle when the requested data
will be ready, so the CPU no longer has to wait between memory accesses.
•SDRAM have to wait for the completion of the previous command to be able to do another
read/write operation.
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6. Types of SDRAM
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7. DDR 1
•Double data rate synchronous dynamic random-access memory (DDR SDRAM) is a class of
memory integrated circuits used in computers.
•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.
•With data being transferred 64 bits at a time, DDR SDRAM gives a transfer rate of (memory bus
clock rate) × 2 (for dual rate) × 64 (number of bits transferred) / 8 (number of bits/byte). Thus,
with a bus frequency of 100 MHz, DDR SDRAM gives a maximum transfer rate of 1600 MB/s.
•"Beginning in 1996 and concluding in June 2000, JEDEC developed the DDR (Double Data
Rate) SDRAM specification (JESD79)." JEDEC has set standards for data rates of DDR
SDRAM, divided into two parts. The first specification is for memory chips, and the second is for
memory modules.
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8. DDR 2
•DDR2 SDRAM is a double data rate synchronous dynamic random-access memory interface.
•DDR2 was introduced in the second quarter of 2003 at two initial clock rates: 200 MHz (referred to as
PC2-3200) and 266 MHz (PC2-4200).
•It superseded the original DDR SDRAM specification, and is superseded by DDR3 SDRAM (launched
in 2007).
•DDR2 DIMMs are neither forward compatible with DDR3 nor backward compatible with DDR.
•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 produce a total of four data transfers per internal clock cycle.
•Since the DDR2 internal clock runs at half the DDR external clock rate, DDR2 memory operating at
the same external data bus clock rate as DDR results in DDR2 being able to provide the same
bandwidth but with higher latency.
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9. DDR 3
•Double data rate type three SDRAM (DDR3 SDRAM) is a type of synchronous dynamic
random-access memory (SDRAM) with a high bandwidth ("double data rate") interface, and has
been in use since 2007.
•It is the higher-speed successor to DDR and DDR2 and predecessor to DDR4 synchronous
dynamic random-access memory (SDRAM) chips.
•DDR3 SDRAM is neither forward nor backward compatible with any earlier type of random-
access memory (RAM) because of different signalling voltages, timings, and other factors.
•The primary benefit of DDR3 SDRAM over its immediate predecessor, DDR2 SDRAM, is its
ability to transfer data at twice the rate (eight times the speed of its internal memory arrays),
enabling higher bandwidth or peak data rates.
•Compared to DDR2 memory, DDR3 memory uses less power.
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10. DDR 4
•In computing, DDR4 SDRAM, an abbreviation for double data rate fourth-generation
synchronous dynamic random-access memory, is a type of synchronous dynamic random-
access memory (SDRAM) with a high bandwidth ("double data rate") interface.
•Released to the market in 2014, it is one of the latest variants of dynamic random-access
memory (DRAM), some of which have been in use since the early 1970s, and a higher-speed
successor to the DDR2 and DDR3 technologies.
•DDR4 is not compatible with any earlier type of random-access memory (RAM) due to different
signalling voltages, physical interface and other factors.
•The primary advantages of DDR4 over its predecessor, DDR3, include higher module density and
lower voltage requirements, coupled with higher data rate transfer speeds. The DDR4 standard
theoretically allows for DIMMs of up to 512 GiB in capacity, compared to DDR3's theoretical
maximum of 128 GiB per DIMM.
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11. COMPARISIONBETWEEN SDRAMs
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12. REFERENCES
•https://www.transcend-info.com/Support/FAQ-296
•http://in.pcmag.com/cpus-components/88228/feature/ddr-vs-ddr2-vs-ddr3-types-of-ram-
explained
•http://www.hardwaresecrets.com/everything-you-need-to-know-about-ddr-ddr2-and-ddr3-
memories/
•http://in.pcmag.com/cpus-components/88228/feature/ddr-vs-ddr2-vs-ddr3-types-of-ram-
explained
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13. THANK YOU
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