HT12D/HT12F pdf datasheet (2 S

The 212 decoders are a series of CMOS LSIs for remote
control system applications. They are paired with
Holteks 212 series of encoders (refer to the encoder/decoder
cross reference table). For proper operation, a
pair of encoder/decoder with the same number of addresses
and data format should be chosen.
The decoders receive serial addresses and data from a
programmed 212 series of encoders that are transmitted
by a carrier using an RF or an IR transmission medium.
They compare the serial input data three times continuously
with their local addresses. If no error or unmatched
codes are found, the input data codes are
decoded and then transferred to the output pins. The VT
pin also goes high to indicate a valid transmission.
The 212 series of decoders are capable of decoding
informations that consist of N bits of address and 12N
bits of data. Of this series, the HT12D is arranged to provide
8 address bits and 4 data bits, and HT12F is used to
decode 12 bits of address information.