This document discusses different types of computer memory. It begins by defining memory and its role in storing programs and data. Memory is then classified as either volatile or non-volatile. Volatile memory, also known as RAM, loses its contents when power is removed but allows for fast read/write access. RAM types are SRAM and DRAM. Non-volatile memory, also called ROM, retains data without power and can only be read. ROM types include Masked ROM, PROM, EPROM, EEPROM, and Flash. Secondary memory, located externally, stores information permanently even without power and includes floppy disks, hard disks, magnetic tapes, USB drives, and optical disks.

1. K.C.S.KASI NADAR COLLEGE OF ARTS & SCIENCE
(Belongs to S.V.H.N.A. Dharma fund)
Accredited with B++ Grade by NAAC
DEPARTMENT OF COMPUTER SCIENCE
MEMORY
By
Mrs.B.RAMA PRABHA,
ASSISTANT PROFESSOR,
DEPARTMENT OF COMPUTER SCIENCE 1

2. Topics to be Covered
Memory
Classification of Memory
RAM
ROM
Secondary Memory
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3. Memory
 It refers to the physical devices used to store programs
(sequences of instructions) or data (e.g. program state
information) on a temporary or permanent basis for use in
a computer or other digital electronic devices.
 It is required for storage and subsequent retrieval of the
instructions and data.
 It exhibits a wide range of technology and types.
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4. Memory Classification
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5. RAM
 RAM stands for Random Access Memory.
 RAM loses its contents when the power is turned
OFF.
 RAM is also called volatile memory.
 The microprocessor can write into or read from this
memory.
 The read/ write memory (R/W M) is popularly known
as Random Access memory (RAM).
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6. DRAM(Dynamic Random Access Memory)
 Dynamic RAM also known as
DRAM, its stored information in a
very short time (a few
milliseconds) even though the
power supply is ON.
 The Dynamic RAM are cheaper
and moderate speed and also they
consume less power.
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7. SRAM(Static Random Access Memory)
 Static RAM- Static RAM also
known as SRAM ,retain stored
information as long as the power
supply is ON.
 SRAM are of higher coast and
consume more power .
 They have higher speed than
Dynamic RAM
RAM
SRAM DRAM
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8. ROM(Read Only Memory)
 ROM does not loses its content when the power turned
off.
 It’s a NON VOLATILE Memory.
 The Microprocessor can only read from this memory.
 Types of ROM:
 Masked ROM
 PROM
 EPROM
 EEPROM
 FLASH
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9. Masked ROM
In this ROM, a bit pattern is permanently
recorded by the masking and
metallization process.
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10. PROM(Programmable Read Only Memory)
 PROM stands for Programmable Read Only Memory.
 This memory has nichrome or poly-silicon wires arranged in a
matrix; these wires can be functionally viewed as diodes or fuses.
 This memory can be programmed by the user with a special
PROM programmer that selectively bums the fuses according to
the bit pattern to be stored.
 The process is known as “burning the PROM,” and the
information stored is permanent 10

11. EPROM(Erasable Programmable Read Only
Memory)
 This memory stores a bit by charging the floating gate of an field
effect transistor.
 Information is stored by using an EPROM programmer, which applies
high voltages to charge the gate.
 All the information can be erased by exposing the chip to ultraviolet
light through its quartz window, and the chip can be reprogrammed.
 Because the chip can be reused many times, this memory is ideally
suited for product development, experimental projects, and college
laboratories. 11

12. EEPROM(Electrically Erasable Programmable
Read Only Memory)
• This memory is functionally similar to EPROM, except that
information can be changed by using electrical signals at the
register level rather than erasing all the information.
• If EE-PROMs are used in the systems, they can be updated from a
central computer by using a remote link via telephone lines.
• This memory also includes a Chip Erase mode, whereby the entire
chip can be erased in 10 ms.
• This memory is expensive compared to EPROM or flash memory.
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13. Flash Memory
 This is a variation of EE-PROM that is becoming popular. The
major difference between the
 flash memory and EE-PROM is in the erase procedure.
 The EE-PROM can be erased at a register level, but the flash
memory must be erased either entire level or at the sector
(block) level.
 These memory chips can be erased and programmed at least a
million times.
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14. SECONDARY MEMORY
 Secondary Memory / Non Volatile
Memory–
 Secondary Memory is external
memory of the computer.
 It is also known as Auxiliary
memory and permanent memory.
 It is used to store the different
programs and the information
permanently.
 Secondary Memory is nature non
volatile. It means data is stored
permanently even if power is
switched off.
The secondary storage devices are:
– Floppy Disks
– Magnetic (Hard) Disk
– Magnetic Tapes
– Pen Drive
– Winchester Disk
– Optical Disk(CD,DVD)
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15. Thank You!!
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