Question:
My PIC16F628A fails to connect, why?
Answer:
The PIC16F62xA (and older PIC16F62x) only have VPP first programming method, so programmer must power target. They also default to LVP (Low Voltage Programming) enabled in configuration word, and will enter LVP mode instead of HVP unless PGM pin is grounded, or connected to the programmer, even if you select HVP method.