$A130xx area usage

The $A13000 to $A130FF address range is special in that the /TIME signal on the cartridge slot is asserted whenever the 68000 accesses it (simplifying the wiring for extra on-cartridge hardware). However it's a limited range, so we want to make sure to avoid stepping on each other.

List of already used $A130xx addresses
AddressesUsed by
$A13000 to $A1300FPrivate use
$A130C0 to $A130CFMega Wifi
$A130D0 to $A130E7Mega Everdrive
$A130EC to $A130EF32X signature
$A130F0 to $A130FFSega mapper

Pier Solar uses the $A13000 to $A1300F region for its custom mapper and EEPROM access. It wouldn't be recommended to put anything there that you want to be usable across multiple games.

$A130E8 is being eyed for potential standarization on EEPROM use.