Memory Map

This page describes the physical memory layout of the ESP8266 family.

Reset Vector

The reset vector is 40000000h or 50000000h, which maps to internal ROM.

Memory Layout

Address	Name	Size	Type	R/W	Description
3FF00000h	dport0	16	I/O	RW?	Memory-mapped I/O.
3FF40000h	drom0	<40000h	ROM	R?	Unconfirmed. Known from the XT2000 memory map.
3FF80000h	dram1	<40000h	RAM	RW	Unconfirmed. Known from the XT2000 memory map.
3FFE8000h	dram0	80k	RAM	RW	User data RAM. Available to applications.
40000000h	brom?	64k	ROM	RW?	Internal ROM. May be writable somehow, but details unknown.
40100000h	iram1	32k	RAM	RW	Instruction RAM. Shadowed version of 40200000h.
40200000h	irom0	<100000h	ROM	RW	SPI Flash ROM?
40211000h	irom0	<100000h	ROM	RW	User Application, slot 1.
40240000h	irom0	<100000h	ROM	RW	User Application start. Mapped to SPI ROM 40000h.
40251000h	irom0	<100000h	ROM	RW	User Application, slot 2.
50000000h	srom	<1000000h	ROM	R?	Unconfirmed. Known from the XT2000 memory map.
60000000h	sram	<4000000h	RAM	RW	Unconfirmed. Known from the XT2000 memory map.
70000000h	iocch	<E000000h	I/O	RW?	Cached I/O. Unconfirmed. Known from the XT2000 memory map.
80000000h	rambp	<10000000h	RAM	RW	Uncached RAM. Unconfirmed. Known from the XT2000 memory map.
90000000h	iobp	<E000000h	I/O	RW?	Uncached I/O. Unconfirmed. Known from the XT2000 memory map.

Exception Vectors

Unconfirmed. From the XT2000 memory map.

Address	Name
40000000h	Reset
40000010h	DebugException
40000020h	NMIException
40000030h	KernelException
40000050h	UserException
40000070h	DoubleException

References

• Forum post Memory Layout, p274
• lx106-rc-2010.1/xtensa-elf/lib/xt2000-rt/memmap.xmm
• ESP SDK linker scripts