Difference between revisions of "SRAM Map"

Revision as of 18:03, 15 November 2016

Overview

All offsets presented here are relative to the start of each save slot. There are $500 bytes for each slot. Note that each slot is mirrored, at a later point in SRAM.

Slot 1: $000; Mirror: $F00
Slot 2: $500; Mirror: $1400
Slot 3: $A00; Mirror: $1900

Only edits to the main copy will be recognized by the game unless the main copy fails its checksum. Each copy has its own checksum.

Addresses $1E00-$1FFE in SRAM are not used. No not assume that the free addresses are initialized to any specific or sensible value. The values from these addresses should be treated as undefined until initialized. Address $1FFF is used by the game to store temporary data.

$1FFE is used as the offset to know where the memory will be stored in the SRAM (02 is the first file, 04 the second and 06 the third)

These offsets directly correspond to $7E:F--- for a particular save file is being played. When the game is finished it writes the information into bank $70 in the corresponding slot + offsets presented here. (e.g. For the second save file, the information will be saved to $70:0500-$70:09FF, and mirrored at $70:1400-$70:18FF.)

Warning

The SRAM save loading routing relies upon an inverse checksum. Additions to any byte in the .srm file, must be subtracted from that save game's checksum to maintain integrity. Failure to observe this precaution will cause the game to attempt to load the mirror copy. Should the mirror copy also fail the checksum verification, the save slot will be cleared.

SRAM Map

$000 - $24F : Data for Rooms

Room Information: There are $128 (296) rooms in in the ROM. Each room has one word of information devoted to it.

High Byte               Low Byte
d d d d b k ck cr       c c c c q q q q      

c - chest, big key chest, or big key lock. Any combination of them totalling to 6 is valid.
q - quadrants visited: 
k - key or item (such as a 300 rupee gift)
d - door opened (either unlocked, bombed or other means)
r - special rupee tiles, whether they've been obtained or not.
b - boss battle won

qqqq corresponds to 4321, so if quadrants 4 and 1 have been "seen" by Link, then qqqq will look like 1001. The quadrants are laid out like so in each room:

--------------- 
|      |      |
|  4   |  3   |
|      |      |
|-------------|
|      |      |
|  2   |  1   |
|      |      |
---------------

$250 - $27F : Unused

This area is believed to have been left to store additional room information that was not included in the final game. This would bring the grand total to $140 (320) possible rooms.

$280 - $2FF : Overworld Event Information

   (one byte per area)

   ?ho???s?

       o - If set, the area will draw its designated overlay when you enter it. 
           e.g. If you're triggered misery mire then the entrance shows up there the next time you enter that area.
           You can view overlays in the latest release of Hyrule Magic (v0.963).
           Other overlays include stairs leading underground, and the removal of the weathervane after it has exploded.
       
       s - If set, the area will draw its secondary overlay when you enter it.
       
       h - If set, heart piece has been collected in this area already.
           Also used for a handful of other sprites.
       
       ? - unknown and probably unused.

$300 - $33F : Unused

This area is believed to have been left to store additional overworld data that was not included in the final game. This would allow for $C0 (192) overworld areas in total. Note areas $80 and $82 are used but don't save data the way the other areas do. (i.e. not here)

$340 - $38B : Items & Equipment

THE COMPASS, BIG KEY, AND DUNGEON MAP WORD LOCATIONS ARE ALL MAPPED OUT THE SAME WAY, AS YOU WILL OBSERVE.

Note: The unused areas would correspond to dungeon numbers $1C and $1E in the variable $7E040C, but alas there are no dungeons in the game with those values.

If you see "(doesn't exist)" it means this feature was not used in this dungeon in the original, in case you were wondering.

Compass1: $364. bit 0: Unused

                             bit 1: Unused
                             bit 2: Compass of Ganon's Tower
                             bit 3: Compass of Turtle Rock
                             bit 4: Compass of Gargoyle's domain
                             bit 5: Compass of Tower of Hera
                             bit 6: Compass of Ice Palace
                             bit 7: Compass of Skull Woods. 

Compass2: $365 bit 0: Compass of Misery Mire.

                             bit 1: Compass of Dark Palace
                             bit 2: Compass of Swamp Palace
                             bit 3: Compass of Hyrule Castle 2 (doesn't exist)
                             bit 4: Compass of Desert Palace
                             bit 5: Compass of Eastern Palace
                             bit 6: Compass of Hyrule Castle (doesn't exist)
                             bit 7: Compass of Sewer Passage (doesn't exist)

BigKey1: $366. bit 0: Unused

                             bit 1: Unused
                             bit 2: Big Key of Ganon's Tower
                             bit 3: Big Key of Turtle Rock
                             bit 4: Big Key of Gargoyle's domain
                             bit 5: Big Key of Tower of Hera
                             bit 6: Big Key of Ice Palace
                             bit 7: Big Key of Skull Woods. 
                       

BigKey2: $367. bit 0: Big Key of Misery Mire.

                             bit 1: Big Key of Dark Palace
                             bit 2: Big Key of Swamp Palace
                             bit 3: Big Key of Hyrule Castle 2 (doesn't exist)
                             bit 4: Big Key of Desert Palace
                             bit 5: Big Key of Eastern Palace
                             bit 6: Big Key of Hyrule Castle
                             bit 7: Big Key of Sewer Passage (doesn't exist)

Dungeon map1: $368. bit 0: Unused

                             bit 1: Unused
                             bit 2: Map of Ganon's Tower
                             bit 3: Map of Turtle Rock
                             bit 4: Map of Gargoyle's domain
                             bit 5: Map of Tower of Hera
                             bit 6: Map of Ice Palace
                             bit 7: Map of Skull Woods. 

Dungeon map2: $369 bit 0: Map of Misery Mire

                             bit 1: Map of Dark Palace
                             bit 2: Map of Swamp Palace
                             bit 3: Map of Hyrule Castle 2 (doesn't exist)
                             bit 4: Map of Desert Palace
                             bit 5: Map of Eastern Palace
                             bit 6: Map of Hyrule Castle
                             bit 7: Map of Sewer Passage (doesn't exist)

Wishing Pond Rupee $36A. Number of rupees in the pond Count

Heart pieces collected: $36B. Number of heart pieces (out of four) you have earned

Health: $36C. Goal (capacity) Health. Each increment of $08 is worth one heart.

                         $04 is a half heart. The max is generally $A0. 
                         The game is coded to not accept health values beyond this.
                 
                   $36D. Actual Health. Same as above, but this reflects
                         your current health status rather than potential.

Magic Power: $36E. Magic power ranges from 0 to $80 (128). Each small bottle refills $10.

                       Setting Magic above $80 causes the magic meter to glitch and you can't 
                       use special items.

Keys: $36F. Number of Keys you have in the dungeon you are currently in.

                       You can earn keys on the overworld but they don't do anything. 
                       If you're in a non-keyed dungeon it will generally read $FF.

Bomb Upgrades: $370. Number of upgrades your bomb capacity has received. Behavior varies after a

                         while. Will probably need recoding to be consistent.

Arrow Upgrades: $371. Number of upgrades your arrow capacity has received.

                         Same as above, more or less.

Hearts filler: $372. Write to this location to fill in a set number of hearts.

                         Make sure to write in a multiple of $08. 
                         Otherwise, you will end up filling the whole life meter.

Magic filler: $373. Write to this location how much magic power you want filled up. The maximum

                        effective value is $80.

Pendants: $374. Bit 0: Red/Wisdom/Hera

                         Bit 1: Blue/Power/Desert
                         Bit 2: Green/Courage/Eastern Palace

Bomb filler: $375. Write to this location to add X bombs to your arsenal. It will not exceed your

                         maximum, as defined with $370

Arrow filler: $376. Write to this location to add X arrows to your arsenal. It will not exceed your

                       maximum, as defined with $371.

Arrows: $377. Can exceed 70.

???? $378. ????

Ability Flags: $379. Bit 0:

                         Bit 1: Swim
                         Bit 2: Run / Dash
                         Bit 3: Pull
                         Bit 4: ----
                         Bit 5: Talk
                         Bit 6: Read
                         Bit 7: ----

Crystals: $37A. Bit 0: Misery Mire

                         Bit 1: Dark Palace
                         Bit 2: Ice Palace
                         Bit 3: Turtle Rock
                         Bit 4: Swamp Palace
                         Bit 5: Gargoyle's Domain
                         Bit 6: Skull Woods

Magic usage $37B. $0: normal consumption

                         $1: 1/2 consumption
                         $2: 1/4 consumption

Keys earned per dungeon:

                   $37C: Sewer Passage
                   $37D: Hyrule Castle
                   $37E: Eastern Palace
                   $37F: Desert Palace
                   $380: Hyrule Castle 2
                   $381: Swamp Palace
                   $382: Dark Palace
                   $383: Misery Mire
                   $384: Skull Woods
                   $385: Ice Palace
                   $386: Tower of Hera
                   $387: Gargoyle's Domain
                   $388: Turtle Rock
                   $389: Ganon's Tower
                   $38A: ??? possibly unused. (Were they planning two extra dungeons perhaps?)
                   $38B: ??? possibly unused.

Game Event Information

Progress Indicator (value, not bitwise) $3C5: $0: Unset, Will put Link in his bed state at the beginning of the game. (Also can't use sword or shield)

     $1: You have a sword and start in the castle on start up.
     $2: Indicates you have completed the first Hyrule Castle dungeon.
     $3: Indicates you have beaten Agahnim and are now searching for crystals.
     $4 and above: meaningless. Though, you could write code using them to expand the event system perhaps.

$3C6: Progress Flags (bitwise)

   0 - Set after your Uncle gives you his gear in the secret passage.
       Prevents him from showing up there again.
   
   1 - Indicates that you've touched the dying priest in Sanctuary.
   
   2 - Set after you bring Zelda to sanctuary?
   
   3 - Unused? (98% certainty)
   
   4 - Set after Link's Uncle leaves your house. It's used to prevent him from respawning there.
   
   5 - Set after you obtain the Book of Mudora (this is a guess)
   
   6 - Seems to be a persistent flag that toggles between two possible
       statements that a fortune teller can give you during your "reading".
       In other words, don't expect this to stay in one state if you're using
       fortune tellers. Has no other known purpose.
   
   7 - Unused? (98% certainty)

Map Icons Indicator 2 (value, not bitwise) $3C7:

   0x00 - ????
   0x01 - ????
   0x02 - ????
   0x03 - The Three Pendants
   0x04 - Master Sword in Lost Woods
   0x05 - Agahnim (skull icon at Hyrule Castle)
   0x06 - Just crystal 1 shown (Sahasrala's idea)
   0x07 - All crystals shown
   0x08 - Agahnim (skull icon at Ganon's Tower)

   All values beyond 8 are invalid, it seems.

Starting Entrance to use: $3C8: Abbreviations:

   LH = Link's House;
   SA = Sanctuary;
   MC = Mountain Cave;
   PP = Pyramid of Power in DW;  
   
   0: Start the game in Link's house always.
   1: SA.
   2: Start in Zelda's Cell (entrance index sanc?).
   3: Secret passage under HC garden (near dying uncle).
   5: LH or SA or MC.
       

Progress Indicator 3 (bitwise) $3C9: 0: If set, means the bum gave you his bottle already.

     1: If set, means that the salesman in the village sold you a bottle already
     2: 
     3: Flute Boy (DW) has been arborated
     4: Thief's Chest has been opened by the middle aged guy
     5: After you save the Smithy's partner, this bit gets set.
     6:
     7: Means Smithies have your sword. Once they give it back it's no longer set. (so nonpermanent)

Lightworld / Darkworld $3CA: 0:

     1:
     2:
     3:
     4:
     5:
     6: If set, we're in dark world. Other wise, in light world.
     7:

Unused? $3CB: ?????

$3CC[0x01] - (Tagalong)

   Tagalong Indicator (who is following you, if anyone?) (value based)
   
   Note: Don't use a value of 0x0F or larger here, as it will likely crash
   the game.
   
   0x00 - Tagalong disabled
   0x01 - Princess Zelda
   0x02 - ???
   0x03 - ???
   0x04 - Old Man?
   0x05 - Zelda (invisible) bitching at you about coming to rescue her.
   0x06 - Blind masquerading as a Maiden
   0x07 - Missing Dwarf (smithyfrog as I call him) in DW
   0x08 - Missing Dwarf in LW
   0x09 - Middle Aged Guy w/ Sign
   0x0A - Kiki the monkey
   0x0B - ???
   0x0C - Thief's chest
   0x0D - Super Bomb
   0x0E - Activated in reaction to acquiring the Master Sword. Used
          to trigger a telepathic message from Zelda indicating that Agahnim's
          goons have come for her at Sanctuary.

$03CD[0x02] -

   Cached Y coordinate of Tagalong after it has been lost by the player.
   Applies to the old man and to the super bomb, at the very least.
   This is intended to be used not as a save game variable, but rather as
   a means of picking the Tagalong back up by getting in contact with it.

$03CF[0x02] -

   Cached X coordinate of Tagalong after it has been lost by the player.
   Applies to the old man and to the super bomb, at the very least.
   This is intended to be used not as a save game variable, but rather as
   a means of picking the Tagalong back up by getting in contact with it.

$3D1: ????

$3D2:

$3D3: Set to 0 normally. Set to $80 if a Super Bomb is going off.

$3D4-$3D8: ????

Player's Name $3D9-$3E4: See appendix for listing of character codes. Note each of the six letters is represented by a 16-bit number.

Validity (Checksum) of the File: $3E5-$3E6: There is a subroutine in the ROM that checks to make sure this value is 0x55AA.

           (Note the reverse byte order in the actual SRAM.) 
           If you alter this your file is automatically tagged for deletion at startup. 
           The game is designed to delete it, it's not a Super NES feature or anything. 
           In short, Don't mess with it. Unused game slots have the value 0x0000 here,
           and you will too if you mess with it - resulting in your save file(s) being wiped
           out.

$3E7-$402 (?) Deaths totals for each dungeon. Each number is 16 bit. Thanks to Euclid for helping verify this!

     $3E7: Sewers
     $3E9: Hyrule Castle
     $3EB: Eastern Palace
     $3ED: Desert Palace
     $3EF: Hyrule Castle 2
     $3F1: Swamp Palace
     $3F3: Dark Palace
     $3F5: Misery Mire
     $3F7: Skull Woods
     $3F9: Ice Palace
     $3FB: Tower of Hera
     $3FD: Gargoyle's Domain
     $3FF: Turtle Rock
     $401: Ganon's Tower

Life/Save Counter: $403-4. Counts the number of times your saved or died in the game, before you beat it.

PostGame Death Counter: $405-6. When you start the game this is written to with the value -1 (0xFFFF). On the game select screen, it will only display a number if this is not 0xFFFF. The max displayable number is 999. When you beat the game, the number of times you died gets recorded here.

Presumed to be unused $407-$4FD: ????

Inverse Checksum: $4FE-F. If you add numbers to the file, you need to subtract from this location. See Side Note 3 for more information.

===================================================================================

Appendix:

Side Note 2: Items other than the standard equipment can be equipped. For instance, it's possible to equip the compass as a sword. By some miracle, the items you end up with often work the same way as their appropriate counterparts. Sometimes they are far superior to the normal items, and sometimes they just suck. At least one item makes your armor invincible! Just experiment a little. Beware, the palletes will not be standard.

Side Note 3: A tutorial on inverse checksums. Let's say I add to location $3EE. Now E = 14 in the decimal system. (Note we are looking at the last digit. "E" that is.) Therefore $3EE is even.

If I add a value to a memory location with an even address, I must subtract from the even address of the inverse checksum. Example: Suppose I add $4 to $305. $305 is odd, so I SUBTRACT $4 from the odd checksum byte: $4FF. If I subtracted from $305, I must add to $4FF. This maintains the "balance" of the file and keeps it from being erased.

Now this will work for slight changes in the checksum, but it takes a bit of insight to recognize that the checksum is really a 16-bit number, not just two 8-bit numbers functioning separately.

(edit later)

Character Codes:

Alpha-numeric

00-A 01-B 02-C 03-D 04-E 05-F 06=G 07-H 08-I^ 09-J 0A-K 0B-L 0C-M 0D-N OE-O OF-P 10-?? 20-Q 21-R 22-S 23-T 24-U 25-V 26-W 27-X 28-Y 29-Z 2A-a 2B-b-2C-c 2D-d 2E-e 2F-f 40-g 41-h 42-k 43-j 44-i 45-l 46-m 47-n 48-o 49-p 4A-q 4B-r 4C-s 4D-t 4E-u 4F-v

60-w 61-x 62-y 63-z 64-0 65-1 66-2 67-3 68-4 69-5 6A-6 6B-7 6C-8 6D-9 6E-"?" 6F-"!" 80-"-" 81-"." 82-"," 85-"(" 86-")"

Special characters (not normally accessible. This is by far an incomplete listing)

A0-small right arrow A1-"'" (apostrophe) A2-HPiece again A3-"empty right hand heart cont." A4-see A7 A5-Same as A7 A6-"Quarter Heart piece, top right corner." A7-"Heart piece,left half" A8-"Heart piece, right half" A9-blank AA-"left arrow" SNES Button Alphabet: AB-A AC-B AD-X AE-Y AF-I B1-blank^

^This code is not the canon encoding of this character. ex. AF is the proper "I". 08 is not.