dynamic RAM


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dynamic RAM

dynamic RAM

The most common type of computer memory and generally available today in the form of synchronous dynamic RAM chips (see SDRAM). Most all volatile memory is dynamic RAM because it uses only one transistor and one storage capacitor for each bit. It is denser and much less costly than "static RAM," its faster counterpart.

Dynamic RAM Is a Total Loser
Unlike non-volatile firmware chips (flash, ROM, EEPROM, etc.), which hold their contents when the power is turned off, both dynamic RAM (DRAM) and static RAM (SRAM) require constant power.

The capacitors in a dynamic RAM chip are electrical storage tanks that do a poor job of holding a charge. They constantly leak, and the memory chip would lose its content were it not for the refresh circuitry that continuously re-energizes the capacitors approximately 15 times per second.

In 1968, dynamic RAM was patented by IBM, and the first commercial chips came from Intel and Mostek in the early 1970s with a capacity of 1,000 bits. See static RAM and memory types.


A Dynamic RAM Cell
DRAM cells are very simple. The combination of voltage on the row and column lines charges a capacitor. The only problem is that the capacitors keep losing their charges, and the bits must be read and re-written to the same state several times each second.







References in periodicals archive ?
When occurs the cache line loading from dynamic RAM, the two LSB bits, are obtained from the numerator, which increments the address with four locations.
These new devices could enable the fabrication of cost-effective memory devices that combine both the high speed of static RAM devices and the high density of dynamic RAM devices.
For those who like to know how these things work: the pup runs on a 64-bit RISC computer processor with eight megabytes of dynamic RAM and a newly developed integrated circuit.
Personal computers, however, will still use the inexpensive dynamic RAM chips and hard drives.
A midrange model, the CPA 2514 dual-LAN router has two synchronous serial ports for connection to a WAN, 4MB dynamic RAM, 32K nonvolatile RAM and 4MB flash memory for running the Cisco Internetwork Operating System.

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