(EPROM). The device is organized into 64K words by. 8 bits (64K bytes). Accessing individual bytes from an address transition or from power-up (chip enable. DESCRIPTION. The M is a , bit UV erasable and electrically programmable memory EPROM. It is organized as 65, words by 8 bits. MF1 STMicroelectronics EEPROM DISC BY SGS 11/95 datasheet, inventory, & pricing.

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From Wikipedia, the free encyclopedia. The switching state of the field-effect transistor is controlled by the voltage on the control gate of the transistor. Retrieved from ” https: It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages than those normally used in digital circuits.

Since the whole memory array is exposed, all the memory is erased at the same time. Exposure time for sunlight of one week or three years for room fluorescent lighting may cause erasure.

Often this label was foil-backed to ensure its opacity to UV. Shining ultraviolet light on any part of an unpackaged device causes a photocurrent to flow from the floating gate back to the silicon substrate, thereby discharging the gate to its initial, uncharged condition photoelectric effect.

Each field-effect transistor consists of a channel in the semiconductor body of the device. Each bit of the word is seprom 1 or 0, depending on the storage transistor being switched on or off, conducting or non-conducting.

27512 EPROM

Source and drain contacts are made to regions at the end of the channel. Photons of the UV light cause ionization within the silicon oxide, which allow the stored charge on the floating gate to dissipate. Like EPROM chips, such microcontrollers came in windowed expensive versions that were used for debugging and program development.


As the quartz window is expensive to make, OTP one-time programmable chips were introduced; here, the die is mounted in an opaque package so it cannot be erased after programming — this also eliminates the need to test the erase function, further reducing cost. In other words, to erase your EPROM, you would first have to X-ray it and then put it in an oven at about degrees Celsius to anneal semiconductor alterations caused by the X-rays.

Even dust inside the package can prevent some cells from being erased. By using this site, you agree to the Terms of Use and Privacy Policy. Leaving the die of such a chip exposed to light can also change behavior in unexpected ways when moving from a windowed part used for development to a non-windowed part for production.

EPROM – Twisty Wrist Arcade and Pinball Parts

Presence of a voltage on this gate creates a conductive channel in the transistor, switching it on. Development of the EPROM memory cell started with investigation of faulty integrated circuits where the gate connections of transistors had broken.

The floating-gate electrode has no connections to other parts of the integrated circuit and is completely insulated by the surrounding layers of oxide. Views Read Edit View history.

While parts of the same size from different manufacturers are compatible in read mode, different manufacturers added different and sometimes multiple programming modes leading to subtle differences in the programming process.

This page was last edited on 8 Novemberat The programming process is not electrically reversible. An insulating layer of oxide is grown over the channel, then a conductive silicon or aluminum gate electrode is deposited, and a further thick layer of oxide is deposited over the gate electrode. The recommended erasure procedure is exposure to UV light at To retrieve data from the EPROM, the address represented by the values at the address pins of the EPROM is decoded and used to connect one word usually an 8-bit byte of storage to the output buffer amplifiers.


This method of erasure allows complete testing and correction of a complex memory array before the package is finally sealed.

The same chip came in somewhat cheaper opaque OTP packages for production. EPROMs are easily recognizable by the transparent fused quartz window in the top of the package, through which the silicon chip is visible, and which permits exposure to ultraviolet light during erasing.

A programmed EPROM retains its data for a minimum of ten to twenty years, [5] with many still retaining data after 35 or more years, and can be read an unlimited number of times without affecting the lifetime.

In effect, the stored 72512 on the floating gate allows the threshold voltage of the transistor to be programmed. Archived PDF from the original on In other projects Wikimedia Commons. The erasing window must be kept covered with an opaque label to prevent accidental erasure by the UV found in 2751 or camera flashes. Digital Design and Fabrication. A control gate electrode is deposited and further oxide covers it. Paper data storage Drum memory Magnetic-core memory Plated wire memory Core eperom memory s Thin-film memory Disk pack Twistor memory — Bubble memory — Floppy disk Cambridge University Press, p.

EPROMs had a limited but large number of erase cycles; the silicon dioxide around the gates would accumulate damage from each cycle, making the chip unreliable after several thousand cycles.