[Coco] Has anyone seen these? Any info?

[wrcooke at wrcooke.net]

   I stand (partially) corrected.  That chip, the W27c512, is indeed an
   EEPROM.  ALL of the other 27C512's I am aware of are EPROM, not
   electrically erasable.  My apologies.

   Digikey seems to agree.  This search:

   [1]https://www.digikey.com/products/en/integrated-circuits-ics/memory/7
   74?k=27c512

   shows 104 results.  The only one that is EEPROM is the Winbond one.
   Strange.

   As for the intent or uses of OTP, there are, or were, several good
   uses.  For instance, a manufacturer that is making maybe 1000 units
   could not justify a mask-programmed ROM.  A normal EPROM with window
   might cost $3 in that quantity, but a OTP without window might only be
   $1.50.  So once an erasable chip was used for development, the OTP
   would be used for production.  There are quite a few other valid use
   cases, that's just one example.

   As for your original question, I can't absolutely say that the product
   is legitimate, but from what I see I would say it most likely is.
   There are some errors in the description that overall are rather minor
   (chip can't be erased, etc.)  It sounds to me like someone who doesn't
   fully understand the product is selling it.  Probably not the person
   who developed it.  But again, I can't say for certain.

   Will

     On July 9, 2019 at 2:16 PM Salvador Garcia via Coco
     <[2]coco at maltedmedia.com> wrote:
     "... using the Winbond W27C512 (64KB) EERPROM,"
     Then the seller's statement is wrong? (The extra "R" not
     withstanding.)
     And this datasheet also says it is an EEPROM:
     [3]http://pdf.datasheetcatalog.com/datasheet/WinbondElectronics/mXrt
     xsu.pdf
     He references the EPROM when he brings up the OTP:
     "Do NOT buy EPROMs (single 'E', as they can only programmed ONCE and
     are old!"
     I see that some manufacturers do use the OTP EPROM nomenclature
     (Microchip). I guess it doesn't make sense to me, since once the OTP
     is programmed, that's it. It can't be erased, at least not by the
     conventional UV lamp method. If anything, I see OTP ROMs falling in
     the PROM group.
     I am just trying to understand the description and determine whether
     this is a legitimate product, given the inconsistencies that we've
     seen in said description.
     Thanks, Salvador
     On Tuesday, July 9, 2019, 01:35:02 PM CDT, [4]wrcooke at wrcooke.net
     <[5]wrcooke at wrcooke.net> wrote:
     <snipped>
       The 27c512 is an EPROM, not EEPROM.  It is, when the package has a
       quartz window, erasable.  However, they make OTP (one time
     programmable
       ) versions which can't be erased so are effectively not
       reprogrammable.  The quartz window is expensive.  That is a
       cost-cutting measure.
       Will
     <snipped>
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References

   1. https://www.digikey.com/products/en/integrated-circuits-ics/memory/774?k=27c512
   2. mailto:coco at maltedmedia.com
   3. http://pdf.datasheetcatalog.com/datasheet/WinbondElectronics/mXrtxsu.pdf
   4. mailto:wrcooke at wrcooke.net
   5. mailto:wrcooke at wrcooke.net
   6. mailto:Coco at maltedmedia.com
   7. https://pairlist5.pair.net/mailman/listinfo/coco