EPROM


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EPROM

Computing
erasable programmable read-only memory

EPROM

[′ē‚präm]

EPROM

EPROM

(Erasable Programmable Read Only Memory) A rewritable storage chip that held its content without power. EPROM chips were written on an external programming device before being placed on the circuit board. For reprogramming, the chip was extracted from the circuit board and placed under an intense ultraviolet (UV) light for approximately 20 minutes (see ultraviolet light).

No longer used, EPROMS evolved into EEPROMs and flash memory, both of which can be erased in place on the circuit board. See EPROM programmer, EEPROM, flash memory and memory types.

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

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


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






The Glass Window
EPROM packages had a glass cover so that the chip could be exposed to ultraviolet (UV) light for erasure. The ceramic chip package had a small quartz window for re-programming, and the package was more costly than other housings. The window was covered with opaque, sticky tape.
References in periodicals archive ?
The EPROM encoder used to generate the binary pattern can be set to develop a 12-bit parallel code, the binary state of which corresponds to either the digital inputs connected to ground or to the supply voltage.
Unlike an EPROM, which requires a separate UV eraser and programmer that can take more than 30 minutes to erase and reprogram, an MTP device can be electrically erased and reprogrammed at least 1,000 times in a few seconds using the same programmer.
imposed anti-dumping duties on Japanese DRAMs and EPROMs and later negotiated a comprehensive agreement to end dumping and open the Japanese market.
Multiple equations of state and calculation algorithms to API, AGA and ISO standards are programmed into the flow computers using EPROM technology.
1977-96 [Percent] Chip type Fisher Laspeyres Paasche Cheapest chain chain chain DRAM's -31.1 -28.2 -34.0 -28.7 EEPROM's -17.8 EPROM's -27.8 -27.9 -28.0 -32.3 ROM's -37.4 -39.3 -35.4 -40.1 Flash (1988-96) -21.7 Fast SRAM's -26.7 -27.3 -25.2 -28.6 Slow SRAM's -19.9 -21.2 -18.5 -28.3
1971: Dov Frohman, an Intel engineer from Israel, invents the EPROM chip, which retains its memory even when the power is turned off.
It incorporates 36 I/Os (four of them selectable), eight counters, four step counters, four digital and four analog timers, and an 800-instruction memory in RAM, EEPROM, or EPROM. The unit operates on 24-v d-c power and has a reaction (throughput) time of under 2 millisec.
Intel Corporation invented the first commercial microprocessor in 1971 and introduced the dynamic random-access memory (DRAM) chip, the erasable programmable read-only memory (EPROM) chip, and the math coprocessor.
The Japanese share of the European EPROM chip market rose from 60% in 1984 to 78% in 1986 (Paltrow, 1987).
Furthermore, in order for the students to experience the complete board-level software design cycle, they write 8085 code to perform a certain task, assemble it, and burn the resulting hexadecimal code into an EPROM. This memory chip is then added to the 8085-based microcomputer board.
The paper documents the processes leading Intel Corporation to exit from dynamic random access memory (DRAM) design and manufacturing in 1984-1985, to halt capacity expansion for erasable programmable read only memory (EPROM) manufacturing in 1991, and to transform itself from a "memory" company into a "microcomputer" company.