Memory Map

Memory Map

Additional RAM is assigned to 0x00200000

0x00000000 ~ 0x00007FFFWork area
0x00008000 ~ 0x001FFFFFUser RAM
0x80000000 ~ 0x80FFFFFFPorts Write
0x80700000 ~ 0x807FFFFFEXTIO area
0xA0000000 ~ 0xA3FFFFFFPort 0x304 Read
0xA4000000 ~ 0xA7FFFFFFPort 0x404 Read
0xA8000000 ~ 0xABFFFFFFPort 0x504 Read
0xAC000000 ~ 0xAFFFFFFFPort 0x604 Read
0xB0000000 ~ 0xB3FFFFFFPort 0x304 Write
0xB4000000 ~ 0xB7FFFFFFPort 0x404 Write
0xB8000000 ~ 0xBBFFFFFFPort 0x504 Write
0xBC000000 ~ 0xBFFFFFFFPort 0x604 Write
0xE0000000 ~ 0xE7FFFFFFInternal backup memory
0xE8000000 ~ 0xEFFFFFFFExternal backup memory
0xEA000000Unknown
0xF8000002 ~ 0xFFEFFFFFPIO
0xFFF00000 ~ 0xFFFFFFFFROM

ROM

The beginning of the ROM holds the entrypoint

0xFFF00000Reset (EXTIO, BMP bootable)
0xFFF00004Reset (EXTIO, BMP can't boot)
0xFFF00008System function vector
0xFFF0000CGet font vector
0xFFFFFD00 ~Debugger interrupt vector
0xFFFFFE00 ~Interrupt handler table
0xFFFFFFF0 ~Hardware reset entries

EXTIO

0x80700000 ~ 0x807FFFFF is probably the EXTIO ROM.

0x807FFFC0 (16 byte)Identification string "PC-FX EXTIO Boot"
0x807FFFD0 (12 byte)Unknown
0x807FFFDC (1 word)Execution vector

Work area

Applications using the official libraries must use the function ROM. How safe is 0x0000 ~ 0x7FBF without official libraries?

0x0000 ~ 0x00C7Pad handling
0x7E00 ~Debugger work?
0x7F00 ~ 0x7F0FUnknown (7up address?)
0x7F20 ~ 0x7F37FONT address
0x7F58 (WORD)Unknown (BMP related)
0x7F5C (WORD)The amount of RAM
0x7FC0 ~ 0x7FFFInterrupt vectors
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