Castlevania II - Belmont's Revenge:RAM map
Please add more.
Legend: [u] is unsigned, [s] is signed, [d] is binary-coded decimal.  is a 2 byte word,  and so on likewise. [b] is big-endian; otherwise, values are assumed to be little-endian.
During entity update routines, register d stores the high byte of the entity data. Belmont's data begins at c000, so d is always c0 during belmont's update routine. Most of Belmont's entity data, such as the velocity data, repeats every 0x100 bytes for subsequent entities.
0x7FFF [u] index of currently-loaded swappable bank. 0xC001 Belmont state (0: standing. 1: walking. 2: crouching. 3: jumping.) 0xC002 Belmont's substate (0: none. 1: attacking, including both whip and subweapon) 0xC009 Belmont's facing (CHR code). Bit 5 is Belmont's facing (20: left. 0: right.); bit 6 is Belmont's vertical flip, etc. 0xC00A Belmont's animation frame 0xC00B Belmont's animation frame minus animation base (?) 0xC00B Belmont's animation timer (when walking, repeatedly counts down from C to 0) 0xC00F [s2] Belmont's Y velocity. Negative is upward 0xC011 [u] Belmont's Y subpixel 0xC012 [u] Belmont's Y pixel 0xC014 [s2] Belmont's X velocity. Negative is leftward. 0xC016 [u] Belmont's X subpixel 0xC017 [u] Belmont's X pixel 0xC018 [u] hitstun 0xC880 game mode (0: konami logo. 1: title screen. 2: title fade-in. 3: stage select and title screen selected. 4: stage entry. 5: normal gameplay. 6: death. 7: game over. 9: Credits. D: password entry. E: intro reel.) 0xC886 current input (1: right. 2: left. 4: up. 8: down. 10: A. 20: B. 40: select. 80: start) 0xC887 input pressed (like 0xC886, but only what was just pressed this frame.) 0xC8C0 [d3] points 0xC8c5 [d] lives ("rest") 0xC8D0 subweapon (0: none. 1: axe (us) / cross (jp). 2: holy water) 0xCC80 [d2] time remaining 0xCC86 [d] hearts 0xCC89 [u] Belmont's hitpoints 0xFF80-0xFFFE stack (127 bytes)