3. Introduction
RAM “Random Access Memory” is a form of
data storage that can be accessed randomly at
any time, in any order and from any physical
location., allowing quick access.
RAM is volatile i.e. its contents are lost when
the device is powered off.
RAM allows the computer to read data quickly
to run applications. It allows reading and
writing.
4. RAM types
The two main types of RAM are static
RAM and dynamic RAM.
Static RAM (SRAM)
4 times more expensive
Very low access time .
Information stored on
RS flip-flops .
No need for refreshing .
They made of transistors
it is used in cache .
They can be either
Bipolar or MOS
technology .
Dynamic RAM (DRAM)
Low cost .
Consumes less power .
Information stored on
FET transistors .
Needs to be refreshed .
These are mostly made
of capacitors .
it is used in main
memory
These are available
only in MOS technology
6. FPM RAM
• Fast Page Mode Dynamic Random Access Memory
It was the original form of DRAM. It waits through the entire
process of locating a bit of data by column and row and then
reading the bit before it starts on the next bit. Maximum
transfer rate to L2 cache is approximately 176 Mbps.
7. EDO RAM
• Extended data-out Dynamic Random Access Memory
does not wait for all of the processing of the first bit before
continuing to the next one. As soon as the address of the first
bit is located, EDO DRAM begins looking for the next bit. It is
about five percent faster than FPM. Maximum transfer rate to
L2 cache is approximately 264 Mbps.
8. SDRAM
• Synchronous DRAM .
• SDRAM is a type of dynamic random access memory which is
synchronized with the clock speed that the microprocessor is
optimized for. SDRAM is about five percent faster than EDO
RAM and is the most common form in desktops today. Maximum
transfer rate to L2 cache is approximately 528 Mbps.
9. DDR RAM
• Double data rate synchronous dynamic RAM is just like
SDRAM except that is has higher bandwidth, meaning greater
speed. It is a newer variant of SDRAM. Maximum transfer rate
to L2 cache is approximately 1,064 Mbps .
10. DDR2 RAM
• Double Data Rate 2 .
• newer version of DDR .
• twice as fast as the original DDR RAM.
• 2003 .
• still is double data rate just like the original DDR.
• DDR2-RAM has modified signaling which enables higher
speeds to be achieved with more immunity to signal noise
and cross-talk between signals .
13. RDRAM
• Rambus dynamic random access memory : Designed by
Rambus, RDRAM uses a Rambus in-line memory module
(RIMM), which is similar in size and pin configuration to a
standard DIMM. RDRAM memory chips work in parallel to
achieve a data rate of 800 MHz, or 1,600 Mbps. Since they
operate at such high speeds, they generate much more heat
than other types of chips .
Dynamic RAM (DRAM)
The term "Fast Page Mode" comes from the capability of memory being able to access data that is on the same page.
486 and Pentium .
Extended Data Out DRAM
Once the required data is found the searching for the next bit will start
Output is about 264 Mbps .
refers to fact that the data output drivers on the memory module are not switched off when the memory controller removes the column address to begin the next cycle .
Synchronous DRAM
Once the first bit is found reads the data from the entire row. Relies on the fact that data is written in rows
Output is about 528 Mbps
SDRAM is capable of running at 133MHz which is about three times faster than FPM RAM and twice as fast as EDO RAM .
Double Data Rate SDRAM
Reads data from memory on the rising clock and falling clock signal. Allowing double capacity over SDRAM
Output is about 1064 Mbps
transfers data twice per clock cycle which effectively doubles the data rate .
become mainstream in the graphics card market and has become the memory standard.