ATtiny4/5/9/10 have one configuration byte, which resides in the configuration section.
| Configuration word address | Configuration word data | |
|---|---|---|
| High byte | Low byte | |
| 0x00 | Reserved | Configuration Byte 0 |
| 0x01 ... 0x07 | Reserved | Reserved |
The next table briefly describes the functionality of all configuration bits and how they are mapped into the configuration byte.
| Bit | Description | Default Value | |
|---|---|---|---|
| 7:3 | – | Reserved | 1 (unprogrammed) |
| 2 | CKOUT | System Clock Output | 1 (unprogrammed) |
| 1 | WDTON | Watchdog Timer always on | 1 (unprogrammed) |
| 0 | RSTDISBL | External Reset disable | 1 (unprogrammed) |
Configuration bits are not affected by a chip erase but they can be cleared using the configuration section erase command (see Erasing the Configuration Section in this chapter). Note that configuration bits are locked if Non- Volatile Lock Bit 1 (NVLB1) is programmed.