Original firmware had 1mhz, 2mhz, and others...
if that's true then the original firmware must be seriously ancient.
On start up it showed 1.12k
I think the list was 10Hz, 50Hz, 100Hz, 250Hz, 439.9956Hz, 441.9890Hz, 443.0170Hz, 1kHz, 2.5kHz, 5kHz, 10kHz, 25kHz, 50kHz, 100kHz, 153.8462kHz, 250kHz, 500kHz, 1mHz, 2mHz, 1000mHz