EPROM is a type of memory chip that can be erased and reprogrammed, allowing data to be updated or changed. It uses ultraviolet light to erase data from all memory cells at once through a transparent window in the chip's package. EPROM is programmed by applying small electrical charges to floating gate transistors within each of the thousands of individual storage cells on the chip.

1. EPROM internal
structure

2. • EPROM means Erasable Programmable Read Only
Memory.

3. • It allows to store data and to erased data and add
new data means it is erasable and
reprogrammable ROM (Read Only Memory).

4. • It is useful for changing or updating memory.

5. • Ultraviolet (UV) light is use for erasing data from
EPROM therefore these chips are mounted on
package which have transparent window.

6. • It is exposed to Ultraviolet (UV) light for about 20
minutes and quartz window is use.

7. • EPROM is programmed by forcing small electrical
charge on a floating gate.

8. • EPROM consists of thousands of storage cells.

9. • Programming phenomenon is called hot electrons
injection.

10. • Floating gate is made from polysilicon material
and it is located in memory cell.

11. • When EPROM exposed to UV light it erased all
data from chip means selective data erasing is
not possible with EPROM.

12. • It is same like ROM but it consists of special
transistor connected through ground.

13. • Special transistor is act as switch and it is
normally turned off.

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