Study of MemoriesTypes of Memory

Memory can be divided into two types, Volatile Memory and Non-Volatile Memory volatile memory temporarily stores the It loses data as soon as the system supply is turned off. Non volatile memory stores data permanently

The different types of memory

Ram stand for Random Access Memory it is a semiconductor based memory where the CPU or the other hardware devices can read and write data it temporarily stores the data and it volatile memory.

Rom stands for Read Only Memory. It stores the data permanently and it is a non- volatile memory. It does not lose the data even after the system turns off. As a result, ROM is a permanent data storage area.

PROM Stands for the Programmable Read Only Memory. It stores programs permanently and is a non-volatile memory. Programming the ROM is sometimes referred to as burning and it requires a special machine called a device programmer or ROM burning.

EPROM stands for the Erasable Programmable Read Only Memory. Ultra- Violet rays can remove the programs from this memory.

EEPROM stands for the Electrically Erasable Programmable Read Only Memory. Electrical signal removes the programs from this memory.

SRAM stands for the Static Random Access Memory

It is a type of semiconductor memory it stores the data. As long as the power is supplied to the system. Once the

Power is turned off or is lost temporarily data stored in sram is lost sram uses six transistors for each memory.

DRAM Stands for the dynamic Random Access Memory

The lifetime of the data in dram is very short . It is approximately for fou.milliseconds. The data in dram are stored in memory cells.

Types of DRAM

Synchronous Dynamic Random Access Memory

SDRAM synchronizes the memory speed with the CPU clock speed.the speed the sdram on the speed of the cpu bus.

It is faster than Sram dram edo dram and vram memories.

Rambus Dynamic Random Access Memory

RDRAM is the fastest computer memory. It sends data very frequently on the dat bus and on very rcycle as a result, the RDRAM memory gets the data transfer speed of 800 MHz.The video memory on the graphic accelerator cards and tha cache memories use this chip.

Double data rate 1:

Receptor tyrosine kinesis (RTKs) play a key role in the communication of cells with their microenvironment. These molecules are involved in the regulation of cell growth, differentiation and metabolism. The protein encoded by this gene is a RTK that is widely expressed in normal and transformed epithelial cells and is activated by various types of collagen. This protein belongs to a subfamily of tyrosine kinas receptors with a homology region to the Dictyostelium disodium protein discoid in I in their extracellular domain. Its autophosphorylation is achieved by all collagens so far tested (type I to type VI). A closely related family member is the DDR2 protein.  In situ studies and Northern-blot analysis showed that expression of this encoded protein is restricted to epithelial cells, particularly in the

kidney, lung, gastrointestinal tract, and brain. In addition, this protein is significantly over-expressed in several human tumors from breast, ovarian, esophageal, and pediatric brain. This gene is located on chromosome 6p21.3 in proximity to several HLA class I genes. Alternative splicing of this gene results

Double data rate 2

DDR2 SDRAM is a double data rate   synchronous dynamic random-access memory  interface. It superseded the original DDR SDRAMspecification, and has since been superseded by DDR3 SDRAM. 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. With data being transferred 64 bits at a time, DDR2 SDRAMgives a transfer rate of (memory clock rate) × 2 (for bus clock multiplier) × 2 (for dual rate) × 64 (number of bits transferred) / 8 (number of bits/byte). Thus with a memory clock frequency of 100 MHz, DDR2 SDRAM gives a maximum transfer rate of 3200 MB/s.