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Will the Sun clear the EPROM?

TechEkspert 20958 35

TL;DR

  • A 27C256 EPROM was tested to see whether sunlight can erase its contents.
  • The chip sat on a building roof for two weeks, and another sample on the eastern wall was read periodically with an Arduino Mini and SD card.
  • The 27C256 stores 32KB, or 32,768 bytes, and the author cites a required dose of 15Ws/cm2 at 253.7nm UV-C.
  • After two weeks in sunlight, most of the EPROM had been deleted, showing that the method works.
  • The erase rate is unpredictable and depends on the weather, so exposure time is hard to estimate.
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  • #31 17873486
    Hektar Zahler
    Level 34  
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    There are cases that are almost documented - e.g. BSI computer in Peżota. Until some time I did not believe it until I found the FF in the eeprom, probably 307. The memory almost erased before my eyes during the replacement of the battery for new - I emphasize because it could have been significant. All settings (ie car configuration) simply "checked" and I had to re-load VIN, PIN code, settings, keys ... Read about it BSI is already writing books. Interestingly, after uploading the settings, the machine works without any reservations.

    ps

    The previous battery was scrap - maybe there is something in it?
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  • #32 17873541
    DJ_Opornik
    Level 21  
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    Indeed, it is not known whether the drivers that came to me in the "virgin" state did not come from machines, eg burned from the starter - no one ever revealed the circumstances of the defect.
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  • #33 17873625
    Hektar Zahler
    Level 34  
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    So it is possible? Unexplainable coincidence - CB radio microphone. The controller has the markings scuffed, but it looks like a D8751H. I left the microphone on while it was connected to the battery and forgot to turn it off. The memory was cleared in this way for about a week before the voltage dropped to zero during that time.

    Will the Sun clear the EPROM? Will the Sun clear the EPROM?
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  • #34 17873901
    HD-VIDEO
    Level 43  
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    Hektar Zahler wrote:
    Can I destroy the UV Win.CIH eprom?
    - YES, because the virus generates random strings to do this.


    Now write how he reprogrammed EPROMA
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  • #35 17873957
    Hektar Zahler
    Level 34  
    Posts: 2333
    Help: 230
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    Buddy, you can program the eprom in the record holder, because that's what we did in the technical school. And even you can see by hand - Link
  • #36 17873968
    HD-VIDEO
    Level 43  
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    Hektar Zahler wrote:
    Buddy, you can program the eprom in the record holder, because that's what we did in the technical school


    You have to write specifically, Win.CIH is to do it on the EPROM CD, damaging it by overwriting the contents.
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Topic summary

✨ The discussion revolves around the effects of UV radiation and other forms of radiation on EPROM (Erasable Programmable Read-Only Memory) chips, particularly in the context of hobbyist practices for erasing and programming these devices. Users share experiences regarding the challenges of erasing EPROMs, the potential for damage from environmental radiation, and comparisons with modern FLASH memory. The conversation also touches on the historical context of EPROM usage in devices like PC motherboards and automation systems, as well as anecdotal evidence of failures attributed to radiation exposure. Additionally, there are mentions of testing methods and the importance of understanding the durability of memory types against various radiation sources.
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FAQ

TL;DR: Sunlight can erase up to 90 % of a 27C256 EPROM in 14 days [Elektroda, TechEkspert, post #15866935]; “first errors showed after two weeks” [Elektroda, TechEkspert, post #15867500] Outdoor UV-C is weak, so full erasure varies with weather and chip design. Why it matters: Field devices that still use windowed EPROMs can lose code unexpectedly if left unshielded.

Quick Facts

• EPROM erase spec: 15 Ws/cm² at 253.7 nm, 12 mW/cm² for 20 min [Elektroda, TechEkspert, post #15866935] • Data-retention rating: >200 years when shielded [Elektroda, TechEkspert, post #15866935] • First bit flips in sunlight: ≈14 days; avalanche after ≈21 days [Elektroda, TechEkspert, post #15867500] • Atmospheric UV-C at ground level: <0.5 % of space value EPA UV Factsheet • Soviet 2716 clones needed several hours of UV to clear [Elektroda, deus.ex.machina, post #15871604]

Can direct sunlight really erase a windowed EPROM?

Yes. A 27C256 left on a roof for two weeks showed most cells changed to 1 (state FF) [Elektroda, TechEkspert, post #15866935] The quartz window passes the UV-B/UV-C that accumulates charge and clears the floating gate.

What wavelength and intensity does a professional EPROM eraser use?

Manufacturers specify 253.7 nm (mercury line). The required dose is 15 Ws/cm², achievable with 12 mW/cm² UV-C for 20 minutes [Elektroda, TechEkspert, post #15866935]

What early symptoms show radiation damage before full erase?

Single ‘0’ bits flipping to ‘1’ appear first. In the monitored chip these isolated errors started after two weeks, long before bulk erase [Elektroda, TechEkspert, post #15867500]

Are modern Flash or EEPROM memories also vulnerable?

Flash lacks a window, yet high-energy particles cause single-event upsets. Space tests record SEU rates around 10⁻⁹ errors/bit-day in low-earth orbit [Ferlet-Cavrois, 2015]. Ground-level UV has negligible effect because the package is opaque.

What protection steps stop accidental field erasure?

  1. Cover the window with a UV-opaque label.
  2. Store boards inside opaque enclosures.
  3. Insert leads into conductive foam to avoid ESD; sunlight can generate surface charge that damages inputs [Elektroda, deus.ex.machina, post #15868080]

Can software like the CIH virus overwrite an EPROM BIOS?

No. Classic desktop BIOS chips after 1995 were Flash, not UV-erasable EPROM. CIH corrupts Flash electrically; true windowed EPROMs need high-voltage VPP pulses unavailable on a running PC [Elektroda, HD-VIDEO, post #15877235]

Edge case: what happens if only part of the chip is lit?

Shadow from the ceramic lid left border rows almost intact while the center erased, creating uneven yellow zones in the image map [Elektroda, krru, post #15867279]
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