AI Interactive Datasheet ATmega128
AVR · megaAVR

ATmega128 memory map

Where everything sits, at its exact address. The ATmega128 keeps program and data apart (Harvard): flash is read in words by the CPU, while registers, I/O and SRAM share one data address space.

Program memory

Flash, with the boot section at its top. Addresses in bytes.

Boot section0x1E000 – 0x1FFFF8 KB
Flash0x0000 – 0x1FFFF128 KB

Data memory

Working registers, I/O registers and SRAM in one space.

External RAM0x1100 – 0xFFFF59.8 KB
SRAM0x0100 – 0x10FF4 KB
I/O registers0x0020 – 0x00FF224 B
Working registers R0–R310x0000 – 0x001F32 B

EEPROM

Non-volatile data, kept without power.

EEPROM0x0000 – 0x0FFF4 KB

Every segment

SegmentSpaceStartEndSizePage
Working registers R0–R31data0x00000x001F32 B
I/O registersdata0x00200x00FF224 B
SRAMdata0x01000x10FF4 KB
External RAMdata0x11000xFFFF59.8 KB
EEPROMeeprom0x00000x0FFF4 KB8 B
FUSESfuses0x00000x00023 B
LOCKBITSlockbits0x00000x00001 B
OSCCALosccal0x00000x00034 B
Flashprog0x00000x1FFFF128 KB256 B
Boot sectionprog0x1E0000x1FFFF8 KB256 B
Boot sectionprog0x1F0000x1FFFF4 KB256 B
Boot sectionprog0x1F8000x1FFFF2 KB256 B
Boot sectionprog0x1FC000x1FFFF1 KB256 B
SIGNATURESsignatures0x00000x00023 B