CassetteMaster | Song of Storms eroding away under UV Light @CassetteMaster | Uploaded 5 years ago | Updated 2 hours ago
What does bit rot sound like?
Here you can hear the Legend of Zelda's Song of Storms song, recorded onto a 128KB EPROM (Erasable Programmable Read-Only Memory) get erased with ultraviolet light.
Link has a sword, and he will slay this data with UV light.
The recording is 8-bit, with a oddball sampling rate of 6622Hz, to make the repeatable song fit perfectly on the 128 kilobytes of space.
An EPROM starts out blank as all ones "FF" in hex. When programming, zeros are written to the IC by injecting charge into floating gate MOSFET transistors. Since the gate is "floating", it acts like a capacitor, and will store the charge for many years. Do discharge the chip, you must shine UV light on it for about 20 minutes (datasheets tend to say 21 minutes). This chip went "blank" in about six minutes.
But beware. Six minutes, and when reading this chip back on an EPROM programmer, there were still three bits I saw that were not blanked. And lowering the Vcc from the requisite 5V down to 3V caused me the be able to recover most of the original data!
What happened, was that enough of the charge had been dissipated to be below the threshold that the chip uses to detect whether the bit is a zero enough to read back as a one when powered at the full 5V, but the threshold was lowered when the chip was read at 3V, causing the data to be visible. So therefore, to fully erase an EPROM, you need the 20 minutes.
Erasing an EPROM live under UV light makes for a fun, interesting experience. The sound stored on EPROM, dissipates, as a strange noise envelops it as all the zeros begin to "avalanche" into ones. EPROMs are a fascinating technology. Thank you, Mr. Dov Frohman!!!
What does bit rot sound like?
Here you can hear the Legend of Zelda's Song of Storms song, recorded onto a 128KB EPROM (Erasable Programmable Read-Only Memory) get erased with ultraviolet light.
Link has a sword, and he will slay this data with UV light.
The recording is 8-bit, with a oddball sampling rate of 6622Hz, to make the repeatable song fit perfectly on the 128 kilobytes of space.
An EPROM starts out blank as all ones "FF" in hex. When programming, zeros are written to the IC by injecting charge into floating gate MOSFET transistors. Since the gate is "floating", it acts like a capacitor, and will store the charge for many years. Do discharge the chip, you must shine UV light on it for about 20 minutes (datasheets tend to say 21 minutes). This chip went "blank" in about six minutes.
But beware. Six minutes, and when reading this chip back on an EPROM programmer, there were still three bits I saw that were not blanked. And lowering the Vcc from the requisite 5V down to 3V caused me the be able to recover most of the original data!
What happened, was that enough of the charge had been dissipated to be below the threshold that the chip uses to detect whether the bit is a zero enough to read back as a one when powered at the full 5V, but the threshold was lowered when the chip was read at 3V, causing the data to be visible. So therefore, to fully erase an EPROM, you need the 20 minutes.
Erasing an EPROM live under UV light makes for a fun, interesting experience. The sound stored on EPROM, dissipates, as a strange noise envelops it as all the zeros begin to "avalanche" into ones. EPROMs are a fascinating technology. Thank you, Mr. Dov Frohman!!!
