Memory Mapping

Mapping Table

Region	Start	End	Size	Notes
Boot ROM	0x0000_0000	-	-	Initial boot code
Main RAM	0x8C00_0000	0x8CFF_FFFF	16 MB	OS + apps + heap
Cached ROM	0x8000_0000	0x81FF_FFFF	512 MB	Cached access
MCS FS	0x8E00_0000	-	-	Filesystem (avoid overwriting!)
Uncached ROM	0xA000_0000	0xA1FF_FFFF	512 MB	Direct, no cache
CPG	0xA415_0000	0xA415_FFFF	64 KB	Clock control
Touch?	0xA405_0100	-	-	Touch register at 0xA405_01F3
Display DMAC	0xB400_0000	-	-	Display DMA controller
XRAM	0xE500_7000	0xE500_9000	8 KB	Fast data RAM (Bank 1)
YRAM	0xE501_7000	0xE501_9000	8 KB	Fast data RAM (Bank 2)
IL Memory	0xE520_0000	0xE520_4000	16 KB	Fast instruction RAM
Direct I/O	0xFEC0_0000	0xFEFF_FFFF	4 MB	Hardware registers
RS Memory	0xFD80_0000	0xFD80_07FF	2 KB	CRITICAL. Retained during standby

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Here’s some informations gathered about the mapping :

• boot rom is at 0x0000_0000, it’s taken from the first part of the flashed rom

• bootloader is at 0x0000_0300 with the LV777 then CASIOABS at 0x0000_3380

• Clock Pulse Generator (CPG) is at 0xA415_0000 to 0xA415_FFFF

• 0xA405_0100 may be the touchscreen, where 0xA405_01F3 changes when screen it touched

• RAM is 0x8c00_0000 to 0x8cff_ffff

• MCS starts at 0x8e00_0000

• Cached ROM is 0x8000_0000 to 0x81ff_ffff

• Uncached ROM is 0xa000_0000 to 0xa1ff_ffff

• Display DMAC start at 0xb400_0000

• There are some “direct Io” from 0xFEC0_0000 to 0xFEFF_FFFF

RAM

When loading a .bin program, it is copied at 0x8cff_0000 and the PC jump to this offset

For hollyhock, we usually use the end of the ram, that space is usually occupied by the mcs file system, but if it’s not fully full, then it should work. Just note that the hollyhock launcher is running from ram, so it can’t overwrite itself…8C00_0000 to 8CFF_FFFF is ram, we use 8CFE_0000 for the launcher (from the run.bin file) and 8CFF_0000 for programs, just look at the launcher how big it is, you can squeeze out a bit if you start your program at 8CFE_8000…