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. 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 ?
If information is not present in cache (in case of a miss) data must be brought from Dynamic RAM memory.
Magnetic random access memory (MRAM) could enable nonvolatile RAM with the high speed of today's static RAM and the high density of dynamic RAM.
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.
The high-end model will reportedly have a keyboard, mouse, flat-panel monochrome or color screen, modem and connection for ATM or ISDN, video conferencing microphone and camera and 4 Mb each of dynamic RAM and flash RAM in a two-pound, laptop-sized box.
Harnish, CPA, and Liz O'Dell Flash memory, or electronically erasable programmable read-only memory (EEPROM), is rewritable like normal random-access memory (RAM), but unlike dynamic RAM (DRAM) or static RAM (SRAM), holds data after the power is turned off.
TwinStar's Richardson, Texas, facility will produce 16- and 64-megabit CMOS dynamic RAM chips and is expected to begin production in May of 1996.

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