Assignment even if power supply is on throughout.

Assignment
# 4

Question:

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What
are the different types of RAM? Briefly describe each type.

RAM:

RAM stands for “Random Access Memory”. It holds data
and instructions temporarily till CPU needs them to process. RAM is considered
“random access” because we can access any memory cell directly if we
know the row and column that intersect at that cell. Any location can be
reached after specifying its address. A program is loaded in RAM before
executing it. The contents of RAM are lost once power supply is cut off so this
means that RAM is a “volatile”
memory. It is also known as “primary
memory”. CPU reads data from RAM and writes data to it.

Two
basic types of RAM are:

Ø  Dynamic
RAM (DRAM)

Ø  Static
RAM (SRAM)

·       
Dynamic
RAM:

Dynamic RAM cannot retain
data for a long time even if power supply is on throughout. It is recharged and
refreshed again and again to maintain its data. This specific operation is the
one from which it gets the name “Dynamic”.
It is the most common type of computer memory. While DRAM is being refreshed,
its contents can’t be accessed. This makes it slow. It is slower and less
expensive than other types.

·       
Static
RAM:

Static RAM can hold data as
long as power supply is on. It uses a technology called “flip flops” to do so. It needs no refreshing to hold data. This
results in it being much faster and expensive than DRAM. They are mainly used
in cache memory.

Ø  Static
RAM forms cache memory while Dynamic RAM forms larger RAM space.

Some
other types of RAM are:

·       
FPM
(Fast Page Mode) DRAM:

This memory is like DRAM but
a little faster. The access time is improved by sending only the row address
once for accessing neighboring memory locations. It is still slower than other
RAMS and is not used for high speed memory purposes.

·       
EDO
(Extended Data Output) RAM:

It can hold data for a
longer period than FPM and can be thought of as an improved version of it. 256
bytes of data is stored in laches and these lashes holds the next same amount
of data. This way programs can be executed sequentially without any delay.

·       
SDRAM
(Synchronous DRAM):

It synchronizes its clock
speed with the system bus. It transfers data when CPU is expecting it. It is
twice faster than EDO RAM.  It works on
Single Data Rate so it can execute only one task per clock cycle.

·       
DDR
(Double Data Rate) SDRAM:

It gives an alternative to
SDRAM. It provides better speed and consumes less power than SDRAM. It sends
data on both edges of the clock.

 

Question:

What
are the different types of ROM? Briefly describe each type.

ROM:

ROM stands for “Read Only Memory”. It is used for
storing data permanently. Unlike RAM, data is not lost when the power supply is
cut off. So, it’s a “non-volatile memory”.
It stores the boot program which runs when the computer is turned on.

Following
are the types of ROM:

·       
PROM:

It stands for “Programmable Read-Only Memory”. Data
is written only once on this type of RAM. Once the data is stored it cannot be
modified so it is called “one-time
programmable device”. PROM is manufactured as blank memory and data is
written on to it using PROM programmer. The process of burning is sometimes
called “PROM burning”.

·       
EPROM

It stands for “Erasable Programmable ROM”. Unlike
PROM it can be programmed more than once. To do so, it is exposed to
ultraviolet light and its contents are removed. After this it can be programmed
again.

 

·       
EEPROM:

It stands for “Electrically Erasable PROM”. It is
like EPROM but its data is removed using electrical current. Unlike EPROM, we
don’t have to erase whole contents of the chip if we need some portion removed.

·       
FLASH
ROM:

It is an updated version of
EEPROM. We can alter many memory locations at once using FLASH ROM.