Start up and Initialization code

[Bella]

I have to code firmware for encoding and decoding the siganls for the wireless Presentation Mouse.
Transmitter
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Infrared Emitter - Vishay TSAL6200
Encoder Microcontroller - PIC 16F627
Receiver
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Infrared receiver - Vishay TSOP4836
Decoder Microcontroller - PIC 16C745

Is it necessary to code the startup code for the PIC microcontroller? or Is it available?. Is it necessary to initialize the PIC microcontroller? Is the initialization code available?.