This document discusses random access memory (RAM). It defines RAM as a form of computer data storage that allows accessing stored data in any random order. The document summarizes the characteristics, types, and evolution of RAM including static RAM, dynamic RAM, synchronous DRAM, and asynchronous DRAM. It also compares RAM and ROM and discusses modern RAM technologies and other applications of RAM like virtual memory and RAM disks.

1. M.KUMARASAMY
COLLEGE OF ENGINEERING
(AUTONOMOUS)
01/10/2013
Guided by,
R.MOHAN,M.Tech
AP/IT DEPT,
Presented by,
M.ANAND(12BIT2003),
R.JEGANATHAN(12BIT2024),
A.KARTHIKA(12BIT2027),
R.KEERTHANA(12BIT2032),
P.KIRUTHIKA(12BIT2033)
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What is RAM…?
Characteristics of RAM,
Types of RAM,
LATEST RAMs,
Other applications,
RAM Vs ROM,
Conclusion.
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4. INTRODUCTION
Random-access memory (RAM) is a form of
computer data storage.
Access stored data in any random order.
form of integrated circuits.
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5. CHARACTERISTICS OF RAM
Volatile;
memory controller;
It allows reading and writing;
Store many words, one per address;
Read and write at a particular address;
space in megabytes(but now in GB);
speed in nanoseconds.
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6. WHY WE GO FOR RAM….?
To read data quickly to run applications.
As Memory cells that can be accessed to
transfer data.
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7. EVOLUTION:
The first RAM modules in 1951 until(1960s-
1970s)
1st generation- MRAM ( 128 KB)in 2003.
In June 2004, Infineon Technologies - 16 MB
RAM.
Since 2006, "solid-state drives“
-256 GB become available.
difference in performance.
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8. BLOCK DIAGRAM OF RAM
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CS- enables or disables the RAM.
ADRS- specifies the address to read from or write
to.
WR-selects reading from or writing to the memory
To read from memory, we set WR=0.
To write to memory, we set WR = 1.
2k x n memory
ADRS OUT
DATA
CS
WR
k
n
n
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9. TYPES OF RAM
RAM
DYNAMIC
S-DRAM A-DRAM
STATIC
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10. STATIC RAM
A type of semiconductor memory.
Modeled using one latch for each bit of storage.
A latch consists of more than 5 transistor.
Uses bistable latching circuitry to store each bit.
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11. Contd.,
most commonly used in video cards.
more expensive.
less dense than DRAM.
An SRAM cell has three different states.
standby (the circuit is idle),
reading (the data has been requested)
writing (updating the contents).
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12. DYNAMIC MEMORY
A single bit of data can be stored with just one
capacitor and one transistor.
physically smaller than SRAMs.
requires constant refreshing.
Memory lasts for Few milliseconds
used for a computer’s main memory.
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13. Contd.,
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disadvantage of DRAM is its speed.
Uses a circuit that acts like a
capacitor.
Types:
Synchronous dram,
Asynchronous dram.
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14. SYNCHRONOUS DRAM
Memory chips are organized into “modules”-
connected to the CPU
Speeds are rated in megahertz
revises the asynchronous memory interface.
All other signals are received on the rising edge
of the clock.
The /RAS and /CAS inputs along with /WE.
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15. Contd.,
programmed into the SDRAM chip itself,
called CAS latency.
The "Load mode register" command is used to
transfer this value to the SDRAM chip.
support for multiple internal banks inside the
DRAM chip.
keep the data bus busy.
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16. ASYNCHRONOUS DRAM
it has power connections, address inputs, & a
bidirectional data lines.
Four active-low control signals:
/RAS, the Row Address Strobe.
/CAS, the Column Address Strobe.
/WE, Write Enable.
/OE, Output Enable.
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17. Contd.,
the signals are generated by a clocked memory
controller,
RAS Only Refresh (ROR)
CAS before RAS refresh (CBR)
Hidden refresh
Classic asynchronous DRAM is refreshed by
opening each row in turn.01/10/2013 RANDOM ACCESS MEMORY 17

18. MODERN RAMs:
Double Data Rate RAM
Similar to regular SDRAM.
memory speeds be 200-266MHz.
lower power consumption.
good for notebooks and other mobile
devices.
RDRAM
in Play station 2 & pentium 4
computers.
transfer rate of 1.6GB per second.01/10/2013 RANDOM ACCESS MEMORY 18

19. OTHER USES OF RAM
Virtual memory:
A part of the hard drive is set aside for a paging file .
physical RAM +paging file = virtual memory.
"swap" portions of RAM to the paging file .
RAM disk:
Shadow RAM:
Shadowing, in computers & embedded systems.
“use shadow BIOS”
ROM will use DRAM locations.
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20. RECENT DEVELOPMENTS:
Non-volatile RAM
Carbon nanotubes are used.
Thermal Assisted Switching (TAS) by crocus
technology.
Spin Torque Transfer (STT) by CROCUS,
HYNIX, IBM technologies.
"Eco RAM", for low power consumption.
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21. RAM vs ROM
RAM ROM
DEFINITION a form of data storage that
can be accessed randomly at
any time, in any order and
from any physical location.
a form of data storage that
can not be easily altered or
reprogrammed.
STANDS FOR Random Access Memory Read-only memory
USE read data quickly to run
applications. It allows
reading and writing.
stores the program required
to initially boot the
computer. It only allows
reading.
VOLATILITY volatile (contents are lost
when the device is powered
off).
non-volatile (contents are
retained even when the
device is powered off).
TYPES static RAM and dynamic
RAM.
PROM, EPROM and EEPROM.
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22. CONCLUSION:
A RAM looks like a bunch of registers connected
together, allowing users to select a particular address
to read or write.
By providing a general interface, it’s easy to connect
RAMs together to make “longer” and “wider”
memories.
REFERENCES:
[1].`Hynix produces its first DDR4modules` -by Graham Smith, Darien. .
[2].`Next-Generation DDR4 Memory to Reach 4.266 GHZ`-by Kingston
technology.
[3].`The DRAM Story`-by ieee.org, 2008.
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