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RAM
(random access memory) is a part of the computer's main memory that is directly
accessible by the CPU. RAM is used to read and write data to it that is
accessed randomly by the CPU. RAM is unstable in nature, which means that if
power is lost, the stored information is lost. RAM is currently used to store
data that has been processed by the CPU. Most programs and data that are
interchangeable are stored in RAM.
The
complete form of RAM is random access memory. The information stored in this
type of memory is lost when the power supply to the PC or laptop is turned off.
The information stored in RAM can be verified with the help of BIOS. This is
commonly referred to as main memory or temporary memory or cache memory or
unstable memory of a computer system.
Integrated
RAM chips are available in two forms:
1.
SRAM (Static RAM)
2.
DRAM (Dynamic RAM)
SRAM
memories have circuits that are capable of maintaining stored information as
long as the power is applied. This means that this type of memory requires
constant power. SRAM memories are used to create cache memory.
SRAM
Memory: Static memory (SRAM) is memories that contain circuits that are able to
maintain their state as long as the power is on. Thus these types of memories
are called unstable memories. The figure below shows the cell diagram of SRAM.
A latch is made by two inverters as shown in the figure. Two transistors T1 and
T2 are used to connect the latch with two bit lines. The purpose of these
transistors is to act as a switch that can be opened or closed under the
control of the word line, which is controlled by the address decoder. When the
word line is at the 0-level, the transistors are turned off and the latch
remains aware. For example, the cell is at state 1 if the argument value at
point A is 1 and point B is 0. This state persists until the word line is
activated.
For
the write operation, the address provided to the decoder activates the word
line to close both switches. The bit value that is to be written to the cell is
then provided through the sense / write circuit and the signals in the bit
lines are then stored in the cell.
DRAM
DRAM
stores binary information as an electric charge that is applied to capacitors.
The information stored on the capacitor is lost over a period of time and thus
the capacitor must be periodically recharged so that their use can be retained.
Main memory is usually made up of DRAM chips.
DRAM
memory: Although SRAM is very fast, but it is expensive because each of its
cells requires multiple transistors. Each cell has a relatively less expensive
RAM DRAM due to the use of a transistor and a capacitor, as shown in the figure
below, where C is the capacitor and T is the transistor. Information is stored
in the DRAM cell as a charge on the capacitor and this charge needs to be
periodically recharged.
To
store information in this cell, transistor T is switched on and an appropriate
voltage is applied to the bit line. This causes a known amount of charge stored
in the capacitor. After the transistor is switched off, its discharge starts,
due to the property of the capacitor. Therefore, the information stored in the
cell can be read correctly only when it is read below some threshold value
before the charge on the capacitor.
Types
of DRAM
There
are mainly 5 types of DRAM:
1.
Asynchronous DRAM (ADRAM): The DRAM described above is asynchronous type DRAM.
The time of the memory device is controlled asynchronously. A special memory
controller generates the control signal required to control circuit timing. The
CPU must take into account the delay in response to memory.
2.
Synchronous DRAM (SDRAM): The access speed of these RAM chips is directly
synchronized with the clock of the CPU. For this, the memory chips are ready
for operation when the CPU expects them to be ready. These memories work on the
CPU-memory bus without imposing weight states. SDRAM is commercially available
as a module for incorporating multiple SDRAM chips and creating the necessary
capacity for modules.
3.Double-Data-Rate
SDRAM (DDR SDRAM): This fast version of SDRAM operates on both sides of the
clock signal; While a standard SDRAM performs its operation on the rising edge
of the clock signal. Since they transfer data to both sides of the clock, the
data transfer rate doubles. To access data at a high rate, memory cells are
organized into two groups. Each group is reached separately.
Rambus
DRAM (RDRAM): RDRAM provides a much higher data transfer rate over a narrow
CPU-memory bus. It uses various speedup mechanisms, such as synchronous memory
interfaces, caching inside DRAM chips, and very fast signal timing. The width
of the Rambus data bus is 8 or 9 bits.
Cache
DRAM (CDRAM): This memory is a special type of DRAM memory consisting of
on-chip cache memory (SRAM) which acts as a high-speed buffer for the main
DRAM.
RAM
usage
Here,
there are important uses of RAM:
RAM
is used in computers as a scrappad, buffer, and main memory.
This
provides a faster operating speed.
It
is also popular for its compatibility
It
provides low power dissipation
Conclusion:
The
complete form of RAM is random access memory.
There
are two main types of RAM: 1) static RAM and 2) dynamic RAM
Static
RAM is the full form of SRAM. In this type of RAM, data is stored using the
state of six transistor memory cells.
DRAM
stands for Dynamic Random Access Memory. This is a type of RAM that allows you
to store each bit of data in a separate capacitor.
FPM
DRAM is a full form of full page mode dynamic random access memory
Rambus
Dynamic Random Access Memory is an extended form of RDRAM
The
RAM optimized for video adapters is called VRAM.
EDO
DRAM is an abbreviation for extended data output random access memory.
Flash
memory is an electrically erasable and programmable permanent type of memory
The
full form of DDR RAM is double the data rate.
SRAM
has shorter access time, so it is faster than DRAM.
RAM
is used in computers as a scrappad, buffer, and main memory.
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