difference between EPROM and EEPROM?  

EPROM requires exposure to short wave UV to be erased and reporgrammed. EEPROM can be reprogrammed selectively (ie just one byte in the middle)

EEPROM are often called flash ROM but it's not quite the same thing.

Answered by pooja at 8:16 PM on April 20, 2008

The difference between EPROM and EEPROM lies in the way that the memory programs and erases. EEPROM can be programmed and erased electrically using field emission (more commonly known in the industry as "Fowler-Nordheim tunneling").
EPROMs can't be erased electrically, and are programmed via hot carrier injection onto the floating gate. Erase is via an ultraviolet light source, although in practice many EPROMs are encapsulated in plastic that is opaque to UV light, and are "one-time programmable".
Most NOR Flash memory is a hybrid style-programming is through Hot carrier injection and erase is through Fowler-Nordheim tunneling.

Answered by ayisha at 8:20 PM on April 09, 2008

EPROM requires exposure to short wave UV to be erased and reporgrammed. EEPROM can be reprogrammed selectively (ie just one byte in the middle)
EEPROM are often called flash ROM but it's not quite the same thing.

Answered by Kajal at 6:06 PM on April 09, 2008

kaushal it is Acronym for electrically erasable programmable read-only memory. Pronounced double-e-prom or e-e-prom, an EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. Like other types of PROM, EEPROM retains its contents even when the power is turned off. Also like other types of ROM, EEPROM is not as fast as RAM. EEPROM is similar to flash memory (sometimes called flash EEPROM). The principal difference is that EEPROM requires data to be written or erased one byte at a time whereas flash memory allows data to be written or erased in blocks. This makes flash memory faster.

Flash Memory: A special type of EEPROM that can be erased and reprogrammed in blocks instead of one byte at a time. Many modern PCs have their BIOS stored on a flash memory chip so that it can easily be updated if necessary. Such a BIOS is sometimes called a flash BIOS. Flash memory is also popular in modems because it enables the modem manufacturer to support new protocols as they become standardized.

Answered by raj u at 3:46 PM on April 09, 2008

EPROM: EPROM stands for Erasable Programmable Read only memory. It is similar to PROM, but its information can be be erased later on by ultra violet light and it can be reprogrammed.

EEPROM: EEPROM stands for Electrically Erased Programmable Read Only memory. It is similiar to EPROM, but its information can be erased by using an high voltage current.

Answered by Deepak at 7:16 AM on April 09, 2008

The difference between EPROM and EEPROM lies in the way that the memory programs and erases. EEPROM can be programmed and erased electrically using field emission (more commonly known in the industry as "Fowler-Nordheim tunneling").

EPROMs can't be erased electrically, and are programmed via hot carrier injection onto the floating gate. Erase is via an ultraviolet light source, although in practice many EPROMs are encapsulated in plastic that is opaque to UV light, and are "one-time programmable".

Most NOR Flash memory is a hybrid style—programming is through Hot carrier injection and erase is through Fowler-Nordheim tunneling.

Answered by Tarun arora at 11:02 PM on April 08, 2008

well kausal EPROM (erasable programmable read-only memory) is programmable read-only memory (programmable ROM) that can be erased and re-used. Erasure is caused by shining an intense ultraviolet light through a window that is designed into the memory chip. (Although ordinary room lighting does not contain enough ultraviolet light to cause erasure, bright sunlight can cause erasure. For this reason, the window is usually covered with a label when not installed in the computer.)

A different approach to a modifiable ROM is electrically erasable programmable read-only memory (EEPROM).
whereas EEPROM (electrically erasable programmable read-only memory) is user-modifiable read-only memory (ROM) that can be erased and reprogrammed (written to) repeatedly through the application of higher than normal electrical voltage. Unlike EPROM chips, EEPROMs do not need to be removed from the computer to be modified. However, an EEPROM chip has to be erased and reprogrammed in its entirety, not selectively. It also has a limited life - that is, the number of times it can be reprogrammed is limited to tens or hundreds of thousands of times. In an EEPROM that is frequently reprogrammed while the computer is in use, the life of the EEPROM can be an important design consideration.

A special form of EEPROM is flash memory, which uses normal PC voltages for erasure and reprogramming.

Answered by sujata at 8:47 PM on April 08, 2008

An EPROM, or Erasable Programmable Read-Only Memory, is a type of computer memory chip that retains its data when its power supply is switched off. In other words, it is non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages than those normally used in electronic circuits. Once programmed, an EPROM can be erased only by exposing it to strong ultraviolet light. That UV light usually has a wavelength of 235nm (for optimum erasure time) and belongs to the UVC range of UV light. EPROMs are easily recognizable by the transparent fused quartz window in the top of the package, through which the silicon chip can be seen, and which permits UV light during erasing.

EEPROM (also written E2PROM and pronounced e-e-prom or simply e-squared), which stands for Electrically Erasable Programmable Read-Only Memory, is a type of non-volatile memory used in computers and other electronic devices to store small amounts of data that must be saved when power is removed, e.g., calibration tables or device configuration.

When larger amounts of more static data are to be stored (such as in USB flash drives) other memory types like flash memory are more economical.

EEPROMs are realized as arrays of floating-gate transistors.

Answered by Bishan Preet at 8:40 PM on April 08, 2008

Acronym for electrically erasable programmable read-only memory. Pronounced double-e-prom or e-e-prom, an EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. Like other types of PROM, EEPROM retains its contents even when the power is turned off. Also like other types of ROM, EEPROM is not as fast as RAM. EEPROM is similar to flash memory (sometimes called flash EEPROM). The principal difference is that EEPROM requires data to be written or erased one byte at a time whereas flash memory allows data to be written or erased in blocks. This makes flash memory faster.

Answered by Ashish Yadav at 7:25 PM on April 08, 2008

The EEPROM uses the same principle as the UV-EPROM. Electrons trapped in a floating gate will modify the characteristics of the cell, and so a logic “0” or a logic “1” will be stored.

The EEPROM is the memory device that implements the fewest standards in cell design. The more common cell is composed of two transistors. The storage transistor has a floating gate (sim-ilar to the EPROM storage transistor) that will trap electrons. In addition, there is an access tran-
sistor, which is required for operations. Figure 9-10 shows the voltages applied on the memorycell to program/erase a cell. Note that an EPROM cell is erased when electrons are removed from the floating gate and that the EEPROM cell is erased when the electrons are trapped in the float-
ing cell. To have products electrically compatible, the logic path of both types of product will give a “1” for erase state and a “0” for a programmed state.

Answered by keshto at 7:17 PM on April 08, 2008