Google suggests that a HCS412 is a KEELOQ=AE Code Hopping Encoder and
Transponder from Microchip.
http://ww1.microchip.com/downloads/en/DeviceDoc/41099D.pdf
(which was aimed primarily at the car fob market)
My best guess is that the 1 at the end is the temperature range. (see page
49)
Could also be a customized version for some large volume OEM, but I doubt
it.

BTW, these are security devices... trying to circumvent it not recommended
or supported by this list.

-Denny



On Mon, Feb 3, 2014 at 1:38 PM, Luis Moreira <
luis.moreira1575@googlemail.com> wrote:

> Hi Guys,
> Looking for some info on a microchip device, the part number on it is
> HCS4121. I not even know what it is, I presume it is a microcontroller or=
 a
> dedicated frequency generating chip. A datasheet would be nice.
> This is from a car remote fob.
> Thank you.
> Best Regards
>                         Luis
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