6.6.4 Extended Z-Pointer Register
This register is concatenated with the Z-register for indirect addressing
(LD/LDD/ST/STD)
of the whole data memory space on devices with more than 64 KB of data memory. If
the device supports more than 64 KB of program memory, the RAMPZ register extends
the Z-pointer to address the entire program memory using the
ELPM/SPM instructions. For more details
regarding the ELPM/SPM instructions usage, refer
to the instruction set summary.
This register is not available if the data memory and program memory in the device are less than 64 KB.
| Name: | RAMPZ |
| Offset: | 0x0B |
| Reset: | 0x00 |
| Property: | - |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| RAMPZ[7:0] | |||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W | |
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Bits 7:0 – RAMPZ[7:0] Extended Z-pointer Address Bits
These bits hold the MSB of the 24-bit address created by RAMPZ and the 16-bit
Z-register. Only the number of bits required to address the available data and
program memory is implemented for each device. Unused bits will always read
‘0’.
- The
LPMinstruction is not influenced by the RAMPZ setting.