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3. What are Upgrade limitation of system?
1.What is Computer memory and Why Do
We Need It?
2. What are the Type of Computer memory
and how they compared?
4. What they mean by multiple channel memory?
5. How to identify memory of pc?
flash ROM and CMOS RAM
Read-Only Memory Read-Write Memory
• non-volatile • volatile
Volatile Memory losses contents when power is
Flash CAMDAM SAM
DAM SAM CAM
SIMM DIMM DDR DDR2 DDR3
DAM (Direct Access Memory)
- direct access to all memory cells
SAM (Sequential Access Memory)
- data reading in sequence
- HDD, optical discs
CAM (Content Addressable Memory)
- associative memory
- returns value according to supplied
The computer can access information held
anywhere in RAM by addressing that part of the
e.g if information stored in the 1000th location in
memory the system does not have to read the
information in the preceding 999 locations to get
there, instead it can access the 1000th location
simply by specifying it.
RAM (Random Access Memory)
Holds data and instructions used by CPU
any piece of data can be returned in a
SRAM (Static Random Access Memory)
-does not need to be periodically refreshed
- more complex internal structure, more expensive,
less capacity than DRAM
DRAM (Dynamic Random Access Memory)
-to keep information must be periodically refreshed
- structural simplicity, high capacity
PRAM( phase change memory )
Single Inline Memory Module
Pins on opposite sides form a single set of
EDO = Extended Data Out
Resides on SIMMs
Sends and receives data
Maximum transfer rate to L2 cache is
approximately 264 megabytes per
DIMM(dual in-line memory module)
Small Outline DIMM(SO-DIMM)
DIMM mean module has Ics
or chips and connection
b/w both side in single line.
Buffered memory put less strain on the electrical load
in Memory controller allowing a stable System that has
several memory module.
ability to detect and correct the error during data
SDRAM PC66 transfer 533MB/s at 66Mhz
SDRAM PC100 Desktop Memory transfer 800MB/s at 100Mhz
SDRAM PC100 Server Memory (ECC) transfer 800MB/s at 100Mhz
SDRAM PC133 Desktop Memory transfer 1,066MB/s at 133 Mhz
SDRAM PC133 Server Memory (ECC) transfer 1,066MB/s at 133 Mhz
Figure -Timeline of memory technologies based on Standard Organization
• Goal of new technology
o Increase overall throughput while retaining accuracy
o RAM manufacturers continue to produce older RAM
Cl or CAS rating
Nomenclature(Identification of module)
Comparison of DDR module notch
Synchronous Graphics RAM
SGRAM is a variant of SDRAM
SGRAM makes use of block-writes to
increase video processing speeds.
SGRAM is single-ported so the CPU
cannot write to it at the same time the
image is being refreshed.
SGRAM is used in high-end graphics
Open the case and look at memory slots
How many slots?
How many filled?
Review module imprint
Examine module for physical size and notch
Read motherboard documentation
See if board supports dual channels or triple
Take motherboard and old memory modules to
a good computer parts store for conformation
Virtual memory takes the place of RAM
You should have a 2:1 ratio of RAM to