I'm trying to simulate my project for the last couple of days. But I'm unable to do so because I can't find the perfect software to simulate.
My project components are:

433MHz RF Tx/Rx
HT12E-HT12D (Encoder-Decoder)
MC89S52
16x2 LCD
UNL2803 (Relay Driver IC)
12V Relay

I was suggested to use Proteus and it doesn't have HT12E-HT12D so I was unable to simulate and wasted days on it.

So, My question is that where can I simulate the circuit comprising all these components?

OR

Any alternative to HT12E-HT12D (Encoder-Decoder) without changing circuit?

 

I doubt you'll get simulators that will sim RF components in real time... When I need to sim this sort of thing I make two halves of each circuit.. then use actual encoder / decoders and use the USB to connect.. Using the COMP component I can get the 4 wires needed through an FT232RL ... This way I can debug the first or second circuit individually in Proteus..