Thank you everyone for your time.
I have just completed testing the program successfully.
The Quad 7 Segment display is counting up. No flickering. :D

The power supply is the same as before.

I can't say what the problem was.

However I have removed the UPS from my Computer and the USB ports ...

While running I am using an external power source.

A 12V transformer
Full Bridge rectifier using 4 X 1N4007 diodes
2200uf 50V Capacitor
7805
103 Ceramic capacitor in Input and Ground Pin of 7805
103 Ceramic capacitor in Output and Ground Pin of 7805

I am getting 4.99 to 5.00 V between ...

I am using a 20MHz crystal oscillator. The numbers are not correctly formed or may be I can't understand the numbers due to flickering.

Today while loading program in the Microcontroller I got an electric shock. Now my Microcontroller is not working at all. No flickering and nothing.
The USB gives ...

Thank you Medelec35 for your reply.

I've tried the One_second Flasher in my Microcontroller.
One second counting is fine. I counted for a minute using stopwatch.

Here is the flowcode: Please suggest How can I stable the Quad 7 segment displays Flickering.

Thank you

Dear Sir,

I am using free version of Flowcode 9.
My problem is:
I have loaded the two Example programs (provided in your website) of Quad 7 segment display into my Microcontroller 16F877A .

https://www.flowcode.co.uk/wiki/index.php?title=Component:_7Segment_(Quad)_(Displays:_Segment)

But the 7 ...