What is MEMORY:
Memory means data storage
in the form of chips, and the word storage refers to memory located in tapes
and disks. However, the meaning of memory is taken as short hand of physical
memory, which means chips that can store data. Some computers use virtual memory,
which increases physical memory on the hard disk.
Each computer comes with
some fixed amount of physical memory. Which is called main memory or RAM.
Think of main memory as
an array in which every box can store single byte information. A computer whose
memory is 1 megabyte. Can store information of 1 Million bytes.
Memory Manufacturers
Kingston, Rambus, Crucial, Samsung, PNY, Micron, Centon.
MEMORY TERMINOLOGY:
Memory Speed: It is
measured in nanoseconds. This is the time at which store data is accessed in
memory. (2 ns-80 ns).
Parity: An easy way in
which error in memory can be checked.
ECC: It is used for
memory correction.
MEMORY BANKS:
This is a socket where
memory is installed.
Example: 4 bank can
install 8 MB memory, so total 32 MB memory.
There are several types
of memory:
ROM computer always keeps
ROM store in small amount, which contains instructions to start the computer.
Nothing can be written to ROM like RAM. It is non-volatile, that is,
information is stored in memory even when computer is turned off.
PROM (Programmable read-only memory):
PROM is a memory chip on
which data can be written only once. Once a program is written to PROM, it is always
located there. Unlike RAM, data remains safe even after the computer is turned
off in PROM. The difference between PROM and ROM (read-only memory) is that
PROM is created as an empty memory, while ROM is programmed only when created.
Writing a data to a PROM chip requires a specific device called the PROM
programmer or PROM burner. The process of programming a PROM is sometimes
called a burning of a PROM.
EPROM (erasable Programmable read-only memory):
There is a specific type
of PROM that is erase by placing it against an ultra-violet light. Once erase
is done it can be reprogrammed. EPROM is also similar to PROM, but requires
electricity to erase it.
EEPROM (Electrically erasable programmable read-only memory):
This is a specific type
of PROM that can be erase by electrical charge. Like other types of PROMs,
EEPROM also retains data even after power off. Like other ROMs, EEPROM is not
as fast as ROM. EEPROM (flash memory) is similar to flash memory (also called
flash EEPROM). The main difference in this is that in EEPROM, data can be
written or read one byte, while in flash memory, data can be written or read in
a block. This makes flash memory faster in speed.
RAM (Random Access Memory):
A volatile storage area
is used by the CPU. Before the program is run, it is loaded into memory which
allows the CPU to directly access the program. Memory is required for any
computer and 64MB of memory is required for your IBM or macintosh.
RAM is the same as man
memory. RAM, when used on its own, means reading and writing memory, meaning
that you can both read and write data from RAM. Most of the RAM is volatile,
which means that it needs a constant flow of power to keep the data secure. The
data in the RAM is erased as soon as the power is turned off.
Types of RAM
SRAM (Static random-access memory):
There is a type of memory
that is much faster and more reliable than DRAM (dynamic RAM). The word static
is derived from the fact that it does not need to be refreshed like dynamic
RAM. Where RAM has an access-time of 60 Nano-seconds, SRAM can provide a
reduced access time of up to 10 nano-seconds. Additionally, its cycle-time is
much shorter than DRAM. Because it does not have to stop between accesses. Its
production is more expensive than DRAM. Due to its high cost, SRAM is often
used similar to memory cache.
DRAM stands for:
Dynamic is from
random-access memory that is used in most personal computers.
Types of DRAM
packages and DRAM memory:
LAPTOP memory:
SODIMM (Small outline DIMM):
There is a smaller
version of DIMM, commonly used in notebook computers. 144 SODIMM pins which
support full transfer of 64 bit.
FPM RAM (Fast Page Mode RAM):
A type of dynamic RAM
that allows fast access to data in a row or page. The function of the page-mode
memory is to eliminate the need for a row address if the data accessed is
located in the previous row. This is sometimes called page mode memory.
SIMM (single-in-line memory module):
There is a small circuit
board consisting of a cluster of memory chips. The SIMM consists of 8 (on
Macintosh) or 9 (on PC) RAM chips. The 9th chip on PC is often used for Parity
error checking. Unlike memory chips, SIMM is measured in bytes rather than
bits. Installing a SIMM is easier than a memory chip. A SIMM is of 30 or 72
pins.
EDODRAM (Extended Data Output Dynamic RAM):
There is a type of DRAM
that is faster than DRAM. Unlike DRAM, which can only access one block of data
at a time, EDORAM starts fetching the next block of memory at the same time the
previous block is sent to the CPU.
DIMM (Dual in-line memory module):
There is a small circuit
board containing memory chips. The SIMM has a 320-bit path for memory chips,
while DIMM requires a 64-bit path, so you can install two SIMMs at a time. You
can only install one at a time in DIMM. The DIMM consists of 168 pins.
SDRAM (Synchronous DRAM):
New type of DRAM which is
much faster than memory. SDRAM in reality synchronizes itself with the CPU's
bus and has the ability to run at a speed of 133 MHz. Ja is three times faster
than FPMRAM and two times faster than FDODRAM. SDRAM is being used in place of
EDODRAM in many new computers. SDRAM provides data in high speed burst. .
DDRSDRAM (Double Data Rate Synchronous DRAM):
A type of SDRAM that
facilitates data transfer at both ends of each clock cycle, effectively
doubling the memory data. DDR-SDRAM is also known as SDRAMII.
RIMM (Rambus Inline Memory Module):
Memory module used with RDRAM
chips. It is similar to the DIMM package, but has a different type of pin
setting. Rambus fired RIMM like a word. It is a term used for modules using the
Rambus technique. It is also sometimes mistakenly used for the Rambus Inline
Memory Module. The RIMM consists of 184 pins. All sockets should be used in
RIMM Installation. RDRAM (Rambus DRAM) is a type of memory (DRAM) used by
Rambus, Inc. , And use C-RIMM to terminate banks.
RDRAM (Rambus DRAM):
It is a type of memory
(DRAM) created by Rambus. The current memory technology used in PC's or
computers transfers data at speeds of 100 MHz, while RDRAM transfers data at
speeds of 300 MHz. In 1997 Intel announced that it would license Rambus
technology to be installed in its future motherboards. Memory from
Rambus technology became
a standard for architecture. But some computer manufacturers are working on
different memory architecture. Called Sync Link DRAM (SLDKAMS)
In some Graphic
accelerator boards, ADRAM is being used instead of VRAM. Intel Pen Pentium III
Xenon processor since late 1999 and Pen
Intel pentium III Xenon
processor # Bir Pentium IV processor # RDRAM was used. Working for a new
version of Intel and Rambus RDRAM is called nPRAM, and which will transfer data
at a speed of 1600 MHz.
SIMM and DIMM sockets
SLDRAM (Sync Link DRAM):
The consortium of some
computer manufacturers called Sync Link consortium developed a new type of
memory. Which is called SLDRAM. SLDRAM is competing against Rambus Memory
(DRAM) for the future PC memory architecture. RDRAM chips now video boards
And other devices have
started to be installed, but SLDRAM is still on paper, that is, imaginary.
Intel backs IRDRAM, ie supports. Therefore, SLDRAM is not yet such an essential
technology.
