DrAzzy:
Unfortunately, my core still won't get him support for 128khz operation - I don't have any speeds lower than 1mhz in the list.With some ISP programmers, there are issues with programming when the target chip is running at a very low speed, because the programmer needs to enter a low speed mode, and this mode isn't well exercised (due to very limited interest in low clock speeds) and doesn't work correctly on some programmers (and in some cases, it depends on the firmware version on the programmer - for example, in some versions of the USBAsp firmware, it needs to get told to use low speed mode by avrdude, in others it uses a jumper on the board, and in others it auto-detects it... I think, at least - I haven't played with low speed mode). It's a mess, and the use cases for such low speed operation are limited - usually you can get comparable power consumption with proper use of sleep mode and a higher clock speed.
Your core is the only one I have installed and is what I used for hat screenshot- or do you mean that the frequency isn't well supported even though it is on the list?