ATEMGA128 View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'ATEMGA128' PDF : 395 Pages View PDF
The five different addressing modes for the data memory cover: Direct, Indirect with Dis-
placement, Indirect, Indirect with Pre-decrement, and Indirect with Post-increment. In
the Register file, registers R26 to R31 feature the indirect addressing pointer registers.
The direct addressing reaches the entire data space.
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-
increment, 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 inter-
nal 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
32 Registers
64 I/O Registers
160 Ext I/O Reg.
Internal SRAM
(4096 x 8)
$0000 - $001F
$0020 - $005F
$0060 - $00FF
$0100
$10FF
$1100
External SRAM
(0 - 64K x 8)
Data Memory
32 Registers
64 I/O Registers
Internal SRAM
(4000 x 8)
$0000 - $001F
$0020 - $005F
$0060
$0FFF
$1000
External SRAM
(0 - 64K x 8)
$FFFF
$FFFF
20 ATmega128
2467O–AVR–10/06
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