Workaround for the obsolete ATTINY15 1.5Mhz clock for FCC exemption?
The RC oscillator of the ATtiny26L can be programmed to run at 1.0, 2.0, 4.0, or 8.0MHz directly without running through a prescaler. Its PLL will still perform a 64x though, so make sure it is disabled if the device must be eligible for the exemption.