EPROM

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EPROM

Computing
erasable programmable read-only memory

EPROM

[′ē‚präm]

EPROM

EPROM

(Erasable Programmable ROM) A rewritable memory chip that holds its content without power. EPROM chips are written on an external programming device before being placed on the circuit board. The chip requires an expensive ceramic chip package with a small quartz window that is covered with opaque, sticky tape. For reprogramming, the chip is extracted from the circuit board, the tape is removed, and it is placed under an intense ultraviolet (UV) light for approximately 20 minutes (see ultraviolet light).

Although still used, EPROMS evolved into EEPROMs and flash memory, both of which can be erased in place on the circuit board. See EPROM programmer, EEPROM and memory types.

A Floating Gate Holds the Charge
EPROMs use a transistor with a floating gate underneath a control gate. To program the bit, a high voltage is applied to the control gate. This causes electrons to tunnel through the insulating oxide layer into the floating gate, which impedes the subsequent operation of the control gate. The 0 or 1 is determined by whether the voltage on the control gate is blocked or not.

The floating gate can hold the charge for more than a decade or until the device is erased; however, EPROMs only support a few hundred erase-write cycles.


An EPROM Cell
An EPROM cell acts like a permanently open or closed transistor. Charging is accomplished by applying voltage to the control gate. When the "floating gate" is charged, it impedes the flow of electrons from the control gate to the silicon, and the 0 or 1 is determined by whether the voltage on the control gate is blocked or not.






The Glass Window
EPROM packages have a glass cover so that the chip can be exposed to ultraviolet (UV) light for erasure.
References in periodicals archive ?
Tower offers a unique combination of an aggressive logic process with the densest EPROM in the industry.
Tower's customers will develop System-level ICs with embedded EPROM for a wide variety of microcontroller and other embedded applications.
Potential risks and uncertainties include, without limitation, risks and uncertainties associated with the (I) development of the EPROM compiler and (ii) development and qualification of the EPROM process.
Tower's target is to begin volume EPROM manufacturing for Fairchild in the second half of this year.
In this long term relationship, Fairchild will provide product definition designed specifically for Tower's dense EPROM process.
In combination with the advanced architecture we use, Tower's silicon will help us deliver the smallest, most cost effective die in the world, density for density," said Howard Shumway, Fairchild's EPROM Product Line Director.
The new products broaden Cypress's EPROM market coverage by addressing lower-speed applications with high-density requirements.
Steve Schrepferman, EPROM product marketing manager for Cypress, said, "While other vendors have exited the EPROM market, Cypress continues to strengthen our commitment to compete aggressively in this area.
Separate Suspension Agreements for DRAMs and EPROMs were concluded at that time between Japanese corporations and the U.
At the same time, a new Suspension Agreement on EPROMs was concluded effective August 1, 1991 between Japanese corporations and the U.
The ability to do full performance test at probe, can mean a very significant savings in test time, especially when testing embedded EPROMs.
New multisite testing capabilities allow testing of up to 16 devices in parallel, greatly reducing overall test time of digital and digital mixed-signal devices with embedded RAM and EPROM.