ff3:ff3us:patches:madsiur:sram

Name SRAM Expansion 2.0
Author madsiur
Link Download
ROM Name Final Fantasy III (USA) 1.0
ROM SHA-1 4F37E4274AC3B2EA1BEDB08AA149D8FC5BB676E7
Header No
$C0FFD8 Internal header SRAM size (from $03 to $05)
Bank $C3 A few offsets related to saving and loading (see asm file)
$C3F091-$C3F122 Extra code (see asm file)
Slot 1 expansion:  $306A00-$307FFF
                   $306000-$3069FF = $7E1600-$7E1FFF

Slot 2 expansion:  $316A00-$317FFF
                   $316000-$3169FF = $7E1600-$7E1FFF

Slot 3 expansion:  $326A00-$327FFF
                   $326000-$3269FF = $7E1600-$7E1FFF

Other SRAM values: $336000-$3375FF (game common SRAM)
                   $337600-$337EFF (unused)
                   $337F00 = last altered savefile
                   $337F01 = rng index
                   $337F08 = checksum value #$E41B (slot 1)
                   $337F0A = checksum value #$E41B (slot 2)
                   $337F0C = checksum value #$E41B (slot 3)
                   $337F0E = checksum value #$E41B (slot 4)

This hack expands SRAM by $1600 bytes, allowing now $2000 bytes for each save slot plus a third 8Kb for general purpose. In original game, only 8Kb of SRAM is used ($306000-$307FFF), each slot occupying $0A00 bytes and $200 bytes for general purpose at the end of the 8Kb block.

With this hack, $306000-$307FFF is used for slot 1, $316000-$317FFF for slot 2 and $326000-$327FFF for slot 3. $336000-$337FFF is used for game SRAM as well. When you play the game, $7E1600-$7E1FFF is still used and copied to correct slot at saving. $336000-$3375FF is copied to correct slot as extra SRAM. At game loading, correct slot is loaded into $336000-$3375FF. So in order to save or load from extra SRAM in your hack, use as an example STA $336000,X or LDA $336000,X.

Since $337600-$337EFF is not used, it means it could be used as scratchpad RAM for temporary things or have a general use common to the three slots.

SRAM could be expanded more but I figured a whole $2000 bytes instead of $0A00 is enough expansion for any hack. In HiROM mapping banks $20-$3F can be used to map SRAM, using always the $6000-$7FFF range of the bank. $C0FFD8 tell the emulator the SRAM size of the ROM.

I have not tested this on sd2snes, Everdrive or real hardware. snes9x 1.55 and bsnes+ were used for testing. If you plan to use this hack and make a cart of your hack after, I have no idea what kind of cartridge you will need or if 32Kb of SRAM is supported by any existing SNES game.

  • ff3/ff3us/patches/madsiur/sram.txt
  • Last modified: 3 weeks ago
  • by madsiur