memory types


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memory types

Following are the different types of RAM and storage technologies used in electronic devices. They fall into two categories: volatile and non-volatile. Volatile chips lose their content the instant power is removed, while non-volatile memories retain their content. Although all the following technologies have the word "memory" in their names, non-volatile memories are really storage chips (see storage vs. memory). For a blast from the past, see early memory.

Volatile Memory



Rewritable - Byte Addressable (DRAM and SRAM)
Dynamic RAM (DRAM) and static RAM (SRAM) chips are the "working storage" in every computer. DRAM is the main memory in a computer and SRAM is used for high-speed caches and buffers. Both types are "byte addressable," which means that data can be read and written one byte at a time. Their major drawback is that DRAM and SRAM require power to hold their content. See dynamic RAM, static RAM and byte addressable.

Future Memories
The Holy Grail for future computer memories is to create a byte addressable RAM chip with the speed of static RAM, the density of dynamic RAM and the non-volatility of flash. See future memory chips.





Non-Volatile Storage



Rewritable Flash - Block Writes - Asymmetric
Flash memory is the most widely used non-volatile storage chip in both computers and consumer electronics (CE) devices. Although reads are random access to the byte level, writing is done at the block level similar to writing a disk sector. Speeds are asymmetric; it takes longer to write than read. See flash memory.

Rewritable - Byte Addressable - Symmetric
EEPROM chips and F-RAM, which have been on the market for some years, along with newer memory technologies, offer the byte addressability of DRAM and SRAM, but do not lose their content when the power is turned off. In addition, read and write speeds are equal or nearly the same. See EEPROM, F-RAM and future memory chips.

Rewritable When Removed (EPROM)
EPROM chips were initially written in an external "programmer" device and had to be removed from the circuit board and placed back in the device for reprogramming. See EPROM.

Permanent (ROM and PROM)
Data and instructions in ROM and PROM chips can never be changed. ROMs are manufactured, while PROMs are programmed in an external device like EPROMs. See ROM and PROM.
References in periodicals archive ?
Using the Wilcoxon signed-rank test, no significant differences were found (p > .05) between the number of specific and categorical memories retrieved by the subjects during the task (M = 13.55, SD = 6.55, and M = 15.82, SD = 10.08, respectively) nor in the latencies for each memory type (M = 9.07 seconds, SD = 5.36 in specific memories, and M = 7.72 seconds, SD = 3.97 in categorical memories).
In summary, this study demonstrated that (-)-linalool, impairs acquisition de several memory types. These data agree with other studies that used other competitive NMDA antagonists in the same tasks.
The same test and repair engine can be programmed with all the test and repair algorithms for all memory types. Typically, designs have clusters of memories within a certain area of a design and incorporate similar memory sizes and types within the clusters.
The typing rules also use region types (Y), which assign a type to every location allocated in a region, and memory types ([Psi]), which assign a region type to every region allocated in memory.
Four DDR4 2400 MHz UDIMM sockets can provide storage up to 64 GB and support both ECC and non-ECC memory types. To enhance reliability, this SMB network appliance platform supports data protection via two pairs of latch-type LAN bypass functions for fail-over option and features BIOS console redirection.
so why are manufacturers trying to sell me all these new memory types, faster buses and different chip interconnect protocols?
In delivering these new features, platform architects must determine the right mix of memory types to balance escalating performance and storage needs against unit costs.
Consequently, the question is how to accommodate not only different memory types at wafer sort, but also different test methodologies.
The reports also reveal distinct memory types and describe a molecule essential to long-term memory storage.