MeatFighter explains the mechanism Castlevania III: Dracula’s Curse uses to save and restore game state through the medium of passwords. The information discussed here applies to the North America and PAL versions released for the NES.

An unbridged table of all 3,294 valid name-and-password combos is located here.

Each column corresponds to a save point. Each row corresponds to a unique combination of name, partner, toggle mask index, and mode. Since the name is hashed to a 3‑bit value, there are only 8 name classes. As shown in the table below, the shortest names that cover all the classes are blank and B–H. These names appear at the left of each row.

Name	Hash
(blank)	4
A	4
B	5
C	6
D	7
E	0
F	1
G	2
H	3
HELP ME	1
AKAMA	2
OKUDA	3
URATA	4
FUJIMOTO	1

The table includes the special names because they modify the behavior of the game.

Read the details in the post here.