Hello guys!
HTBoss:
1) Yes, there is no room in the altera to implement timing switch for 1024kb firmware, so, it works only in Pentagon mode.
2) My Dandanator Mini works fine with Karabas-128 and Karabas-128 with 1024 ram mod.
3) The BUS_N_IORQGE signal is LOW by default, there is a pull-down resistor. This is correct for Karabas and it works this way

4) Buzzing in a speaker - that is not normal, probably kind of bad soldering or short somewhere. Please double-check.
Maryjan, i'm the author of the 1024 mod and related altera firmware
