mappers:
key: 

Complete - what it sounds like
Good - thought to be complete
Decent - mostly compatible, but many significant edge cases not tested
Minimal - Important games are playable, but emulation is known not to be complete
~NEEDED~ - Needed for neshawk 1.0
Needed - Someone should do this
Nothing - Not implemented
Junk - Who cares about this. Not enough games, or unlicensed junk or no interesting games

Mapper compatibility does not warrant game compatibility, which may be contingent on other aspects of emulation.
It is just a rough guide for future work.
Open bus and bus conflict emulation is not considered complete or thorough in any event.

000	NROM		Complete
001	SxROM=MMC1	Decent
002	UxROM		Good
003	CNROM		Good
004	MMC3		Decent
005	ExRom=MMC5	Minimal
007	AxROM		Good
009	PxROM=MMC2	Complete
010	MMC4		Complete
011	Misc		Complete
013	CPROM		Complete
015	Multicart	Junk
016	Bandai		Started doesn't work(+159) (probably needs eprom emulation)
018	Jaleco*		Nothing
019	Namcot106	Decent (but no sound) (+210)
021	VRC4		Decent 
022	VRC2		Decent
023	VRC2/4		Decent
024	VRC6		Decent (no sound)
025	VRC4?		Decent
026	VRC6(newer)	Decent (but no sound)
032	Irem_G101	Complete
033	Taito		Complete
034	Misc		Complete
044	Multicart	Junk
045	Multicart	Junk
046	Multicart	Junk
047	MMC3Multi	Decent
048	MMC3Variant	Decent
049	Multicart	Junk
050	Pirate		Junk
052	Multicart	Junk
057	Multicart	Junk
058	Multicart	Junk
060	Multicart	Junk
061	Multicart	Junk
062	Multicart	Junk
064	Tengen		Good
065	Misc (J)	Nothing
066	GxROM		Complete
067	Sunsoft-3	Nothing
068	Sunsoft-4	Complete
069	FME7		Minimal
070	Misc		Complete
071	Camerica	Complete
072	Misc (J)	Nothing
073	VRC3		Good
074	Pirate (CN)	Junk
075	VRC1		Complete	
076	Misc (J)	Nothing
077	Misc (J)	Complete
078	Misc		Complete
079	NINA-06		Complete
080	Misc (J)	Nothing
082	Misc (J)	Nothing
085	VRC7		Decent (no OPL sound)
086	Misc (J)	Decent (no sound)
087	Misc (J)	Complete
088	Misc (J)	Nothing
089	Sunsoft-2	Complete
090	Garbage		Junk (+209)
091	Pirate		Junk
092	Misc (J)	Nothing (similar to 072)
093	Sunsoft-2	Good
094	Misc (J)	Complete
095	MMC3Variant	Complete
096	Misc (J)	Nothing
097	Misc (J)	Complete
105	NES-EVENT	Minimal (not entirely tested, no timer/IRQ, no dip switches)
107	Unlicensed	Complete
112	Misc (CN)	Nothing
113	=USELESS=	Junk
115	MMC3Variant	Nothing
118	TLSROM		Complete
119	TQROM		Complete
140	Misc (J)	Complete
152	Misc (J)	Complete
154	Misc (J)	Nothing
159	Bandai		{{See 016}}
164	Pirate		Junk - Started
165	Pirate		Junk
180	Misc (J)	Complete (but we don't implement the crazy climber controller) 
182	MMC3Variant	Nothing
184	Sunsoft-1	Complete
185	Misc (J)	Complete
189	MMC3Variant	Nothing
191	Pirate		Junk
192	Pirate		Junk
193	Unlicensed	Junk - Started
194	Pirate		Junk
200	Multicart	Junk
201	Multicart	Junk
203	Multicart	Junk
205	Multicart	Junk
*206 Namcot109	Complete (missing from disch docs)
207	Misc (J)	Nothing
209	Garbage		{{See 090}}
210	Namcot		Decent {{See 019}}
225	Multicart	Junk
226	Multicart	Junk
227	Multicart	Junk
228	Unlicensed	Nothing
230	Multicart	Junk
231	Multicart	Junk
232	Camerica	Complete
233	Multicart	Junk
234	Misc		Nothing
240	Misc (CN)	Complete
242	Misc (CN)	Complete
243	Misc		Nothing
245	Pirate		Junk
246	Misc (CN)	Nothing