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Dual-ported RAM (DPRAM), also called dual-port RAM, is a type of random-access memory (RAM) that can be accessed via two different buses.. A simple dual-port RAM may allow only read access through one of the ports and write access through the other, in which case the same memory location cannot be accessed simultaneously through the ports since a write operation modifies the data and therefore ...
Synchronous dynamic RAM (SDRAM) significantly revises the asynchronous memory interface, adding a clock (and a clock enable) line. All other signals are received on the rising edge of the clock. The RAS and CAS inputs no longer act as strobes, but are instead, along with WE , part of a 3-bit command:
DPRAM Texas Instruments? NMOS ? [73] [74] January 1985: μPD41264 256 kbit DPRAM (VRAM) NEC ? NMOS ? [75] [76] June 1986? 1 Mbit PSRAM Toshiba ? CMOS ? [77] 1986 ? 4 Mbit DRAM NEC 800 nm NMOS 99 mm 2 [65] Texas Instruments, Toshiba 1,000 nm CMOS 100–137 mm 2: 1987 ? 16 Mbit DRAM NTT 700 nm CMOS 148 mm 2 [65] October 1988? 512 kbit HSDRAM IBM ...
If at this point, CPU 2 issues a test-and-set to memory location A, the DPRAM detects the special flag value, and as in Variation 1, issues a BUSY interrupt. Whether or not CPU 2 was trying to access the memory location, the DPRAM now performs CPU 1's test. If the test succeeds, the DPRAM sets memory location A to the value specified by CPU 1.
The DDR interface accomplishes this by reading and writing data on both the rising and falling edges of the clock signal. In addition, some minor changes to the SDR interface timing were made in hindsight, and the supply voltage was reduced from 3.3 to 2.5 V. As a result, DDR SDRAM is not backwards compatible with SDR SDRAM.
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DDR3 is a DRAM interface specification. The actual DRAM arrays that store the data are similar to earlier types, with similar performance. 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 ...
Low-Power Double Data Rate (LPDDR), also known as LPDDR SDRAM, is a type of synchronous dynamic random-access memory (SDRAM) that consumes less power than other random access memory designs and is thus targeted for mobile computing devices such as laptop computers and smartphones.