MM (U) Ram

800EA8D0 - sets form to be transformed to by Skull Kid (4 = normal, 3 = deku...)
801448A4 - starting form
80145348 - overwrites starting form before game starts
8016A4B8 - check for ocarina (ususally to determine if it's first cycle)
80143A10(warp_point) - set warp point as active (owl statues)
 
803E6B20 is an important address (like 80212020 in OoT debug)
803E87D0 = loaded actor list (for each actor type, number of actors, pointer to first actor of that type)
 
803E8918 = highlighted/targeted actor
 
Ocarina:
8019BF44 = A button
8019BF88 = Down-C
8019BFA4 = Right-C
8019BFC0 = Left-C
8019BFD8 = Up-C
 
801D7020 = last 8 notes played
 
801518B0(803E6B20, msg_no) - show a message
 
800FEC90(address1,address2,size) - copy data from one RAM address to another
 
80080A08(*something) - load_file
something:
u32 rom_v_addr
u32 ram_addr
u32 size
 
80080C90(ram_addr,rom_addr,size) - copy data from ROM to RAM (note rom_addr is always the decompressed location)
 
801445E4(address, size) - calculates checksum (for savefile)?
 
8015B100 - always branch for instant text
801DF834 - needs to be replaced or text causes softlocks sometimes with above hack
 
80145360 - sets start area, exit number (new game)
80145350 - sets start area (normally)
 
800EA8D0 - form in save cutscene (first SoT, usually changes you back to deku)
 
f32 80086FDC() - PRNG (pseudo random number generator) (return value in $f0)
 
80112E80(803E6B20, item_no) - item giving function (puts in inventory)
value list:

00 ocarina
01 bow
02 fire arrow
03 ice arrow
04 light arrow
05 fairy ocarina
06 bomb
07 bombchu
08 deku stick
09 deku nut
0a magic bean
0b slingshot
0c powder keg
0d pictobox
0e lens of truth
0f hookshot
10 great fairy sword
11 hookshot (OoT)
12 empty bottle
13 red potion
14 green potion
15 blue potion
16 fairy
17 deku princess
18 milk
19 milk (half)
1a fish
1b bugs
1c blue fire
1d poe
1e big poe
1f water
20 hot water
21 zora egg
22 gold dust
23 mushroom
24 seahorse
25 chateau romani
26 eel
27 empty bottle
28 moon's tear
29 town deed
2a swamp deed
2b mountain deed
2c ocean deed
2d room key
2e mama's letter
2f letter to kafei
30 pendant
31 map
32 deku mask
33 goron mask
34 zora mask
35 fierce deity's mask
36 mask of truth
37 kafei's mask
38 all night mask
39 bunny hood
3a keaton mask
3b garo's mask
3c romani mask
3d circus leader's mask
3e postman's hat
3f couple's mask
40 great fairy's mask
41 gibdo's mask
42 don gero's mask
43 kamaro's mask
44 captain's hat
45 stone mask
46 bremen mask
47 blast mask
48 mask of scents
49 giant's mask
4a bow + fire arrow
4b bow + ice arrow
4c bow + light arrow
4d kokiri sword
4e razor sword
4f gilded sword
50 helix sword (can't equip)
51 hero's shield
52 mirror shield
53 quiver (30)
54 quiver (40)
55 quiver (50)
56 bomb bag (20)
57 bomb bag (30)
58 bomb bag (40)
59 wallet (unused)
5a wallet 2
5b wallet 3
5c fishing rod
5d odolwa's remains
5e goht's remains
5f gyorg's remains
60 twinmold's remains
61 sonata of awakening
62 goron lullaby
63 new wave bossa nova
64 elegy of emptiness
65 oath to order
66 saria's song
67 song of time
68 song of healing
69 epona's song
6a song of soaring
6b song of storms
6c sun's song
6d bomber's notebook 
7b heart piece
83 heart
84 green rupee
85 blue rupee
87 red rupee
88 purple rupee
89 silver rupee
8e deku nuts (10)
93 arrows (10)
94 arrows (20)

800B8A1C(80410440,803E6B20,item,...) - get item (Link holds it over his head) Get Item (ovl_player_actor)

MM to OoT Function comparison

Functions likely to be the same.

Majora's Mask | Ocarina of Time
              |
8008907C      | 800FD9AC
800B8A5C      | 8001F548
800B908C      | 8001F940
800C2B18      | 8002829C
800C3060      | 800286CC
800C4408      | 800297A4
800C54F4      | 8002A6B8
800C61DC      | 8002B1E0
800C84A8      | 8002CB40
800C8664      | 8002CD6C
800C86A8      | 8002CDA0
800C8F0C      | 8002D570
800C8F5C      | 8002D5B8
800C8FE0      | set_actor_size
800C92FC      | 8002D8E0
800C9504      | 8002D9A4
800C984C      | 8002DB48
800C9E18      | 8002DF38
800CA00C      | 8002E084
800CA5A0      | 8002E4B4
800CBB00      | 8002F410
800CBB24      | 8002F434
800CBCA8      | 8002F554
800CC05C      | 8002F7DC
800CC0E8      | 8002F828
800CC1F0      | 8002F8F0
800CC304      | 8002F9EC
800D01A8      | 80032C7C
800D0558      | 80033260
800D0938      | 80033748
800D1500      | 8003426C
800D2E9C      | 80035628
800D2EC8      | 80035650
800D2F28      | 8003573C
800D5000      | 80038A28
800DAB74      | 8003DE84
800DBBA0      | 8003EB84
800DFD28      | 800DFD28
800F8E88      | 8005A9F4
800FA04C      | 8005BCC8
800FA3FC      | 8005C050
800FA760      | 8005C3AC
800FA958      | 8005C4AC
800FB688      | 8005D018
800FB6F4      | 8005D060
800FB7E4      | 8005D104
800FBFF8      | 8005D79C
800FC268      | 8005D9F4
800FC4D8      | 8005DC4C
8010174C      | 80061ED4
801021D4      | 800626DC
801023A0      | 800628A4
80102AB8      | 80062D60
8010DE50      | 8001F940
8011DA7C      | 80077834
8011DAD8      | 80077870
8011DC18      | 800778AC
8011DDE4      | 80077A00
8011E3A8      | 80077E40
8011E458      | 80077E9C
8011E490      | 80077ED0
8011E7C4      | 80077FD0
8011E838      | 80078028
8011E988      | 80078068
8011EB18      | 800780DC
8011EE40      | 8007841C
8011EF04      | 8007869C
8011F020      | 800787BC
80120C18      | 80079D8C
80120C98      | 80079DF0
80120D1C      | 80079E58
801219AC      | 8007A764
80121A28      | 8007A7C4
801467E8      | 8008F104
80148E50      | 80090480
8014FCF8      | 80093D18
8014FDE8      | 80093D84
801501C0      | 80094044
801512B8      | 80094F40
8015AB30      | 800A15C8
8015AFD8      | 800A1AC8
8015B950      | 800A2000
8015E160      | 800A457C
8015E4A0      | 800A49FC
8015EC98      | 800A51A0
8015ECFC      | 800A51E8
8015ED70      | 800A5240
8015EDE8      | 800A529C
8015EED0      | 800A534C
8015F29C      | 800A56C8
8018C4E0      | 800FA00C
801A0BE4      | 8008E988
801A1DFC      | 800C0C88
801AEF64      | 800C6AC4
801AEFE4      | 800C6B54
801B4E3C      | sinf
801BBE44      | 800FD250
801BC098      | 800D0664
801BC18C      | 800D084C
801BC220      | 800D0884
801BC29C      | 800D08D8
801BC2DC      | 800D08FC
801BC330      | 800D0930
801BC3A4      | 800D0984
801BC4C0      | 800D0A8C
801BC5B8      | 800D0B70
801BCB5C      | 800D0D20
801BCEE0      | 800D0ED4
801BD25C      | 800D1084
801BDCDC      | 800D1A88
801BDD84      | 800D1AF4
801E72C8      | 80078884
801EFA78      | 800F8D04

current file stuff

801EF670
 
relative to 801EF690:
 
0x0 form, ?, Tatl flag, ?
0x4 "ZELDA3" 0000 
0xC [filename]
0x14 max health, current health
0x18 magic meter, current magic, rupees
 
0x2C equipped items
 
0x4C ?, equipment, ?, ?
0x50 item screen
0x68 mask screen
0x80 item ammo
0x9C quest stuff/songs

One interesting note - right after the default save file information in the ROM there is another set of save file information which is never used afaik (probably for testing). You can actually set it up so this is used as the default when starting a new file but I didn't make any notes on that. Also, since there is an item between blue and red rupees it seems very likely that a rupee worth 10 was supposed to be in the game at one point. I forget if this actually functions or not though (appears as a red rupee without text).