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simple question about new eprom?

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Moss

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When the eprom(27C512) is new , all bytes are FF? Corect?
 

mr_ghz

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Hi Moss,

Yes, you're right. An unprogrammed EPROM cell (no charge on the gate)
gives a logic '1'. If you put charge on this gate (programming), the
corresponding bit changes to '0'. With UV-Light (ionizing the air), this
charge can be removed and the bit changes back to '1'.
Without UV-Light the charge lasts for many years (data rentention),
normally >10 years fo old EPROM's newer normally >100 years.

Bye
 

BENOIT

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Note that Cypress Eproms have 00 inside when Blank.
MB.
mr_ghz said:
Hi Moss,

Yes, you're right. An unprogrammed EPROM cell (no charge on the gate)
gives a logic '1'. If you put charge on this gate (programming), the
corresponding bit changes to '0'. With UV-Light (ionizing the air), this
charge can be removed and the bit changes back to '1'.
Without UV-Light the charge lasts for many years (data rentention),
normally >10 years fo old EPROM's newer normally >100 years.

Bye
 

Moss

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Thanks both of you!
My chips are ST, so new must be filled with FF.
 

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