Arduino Tiny ISP code modified to program ATMEGA MCU hooked up to slow oscilator crystals
Original code: https://code.google.com/p/arduino-tiny/downloads/detail?name=tiny-isp-2-0100-0001.zip&can=2&q=
Modifications: TinyISP_SPI.cpp - line 152 and 162 - delay time increased in bit-banging SPI code for slow clocks. Values 55 works for 32768Hz. For slower clocks, they need to be increased further.