The Indirect with Displacement mode reaches 63 address locations from the base address given
by the Y- or Z-register.
When using register indirect addressing modes with automatic pre-decrement and post-incre-
ment, the address registers X, Y, and Z are decremented or incremented.
The 32 general purpose working registers, 64 I/O registers, and the 4096 bytes of internal data
SRAM in the ATmega128 are all accessible through all these addressing modes. The Register
file is described in “General Purpose Register File” on page 12.
Figure 9. Data Memory Map
Memory Configuration A
Memory Configuration B
Data Memory
Data Memory
$0000 - $001F
$0020 - $005F
160 Ext I/O Reg. $0060 - $00FF
32 Registers
64 I/O Registers $0020 - $005F
$0060
$0000 - $001F
32 Registers
64 I/O Registers
Internal SRAM
(4000 x 8)
$0100
Internal SRAM
$0FFF
$1000
(4096 x 8)
$10FF
$1100
External SRAM
(0 - 64K x 8)
External SRAM
(0 - 64K x 8)
$FFFF
$FFFF
20
ATmega128(L)
2467P–AVR–08/07
ATMEL [ ATMEL ]
