ATtiny4/5/9/10 have one calibration byte. The calibration byte contains the calibration data for the internal oscillator and resides in the calibration section. During reset, the calibration byte is automatically written into the OSCCAL register to ensure correct frequency of the calibrated internal oscillator.
| Calibration word address | Configuration word data | |
|---|---|---|
| High byte | Low byte | |
| 0x00 | Reserved | Internal oscillator calibration value |
| 0x01 ... 0x07 | Reserved | Reserved |