Ссылки - Прошивка atmega8

Programming ATmega8 Using Arduino IDE
https://www.hackster.io/hami/programming-atmega8-using-arduino-ide-90c2ad

ATmega8 bootloader, code, Arduino IDE
https://www.youtube.com/watch?v=62rhbh9_GKw

(прошивка через ардуино)

How To Burn Arduino Bootloader and sketch for ATMEGA8 ?
https://www.youtube.com/watch?v=eX4m_YXit9U

https://arduino-projects-free.blogspot.com/2017/10/how-to-burn-arduino-bootloader-and.html

Adition:

Programming ATtiny13 with Arduino Uno
https://www.hackster.io/taunoerik/programming-attiny13-with-arduino-uno-07beba