It's in HD:
https://budgetlightforum.com/t/-/44344
Nothing actually changed in the code, just some of ATMEL's register macros. As I recall TIMER0_OVF_vect had to change to TIM0_OVF_vect and TIMSK and to change to TIMSK0. there might ahve been another one but it will be obviouus when you try it.
So I change them to _TIMER0_OVF_VECT_ and _TIMSK_ and in fr-tk-attiny.h
add
#if ATTINY == 13
#define _TIMSK_ TIMSK0
...
you get the point.
I'll post this new version up soon though, but that's all I change, oh and removing the override on that on option.