PPU variants

Beyond the well-studied 2C02G, we know of the following PPU revisions, both made by Ricoh and other manufacturers:

RP2C02	Suspected to exist, none found. Probably too buggy to be usable.
RP2C02A	differences unknown. Substantial timing differences attested relative to revision D
RP2C02B	"
RP2C02C	"
RP2C02D	differences unknown.
RP2C02E	OAMDATA is not readable. Various OAM evaluation bugs
RP2C02G	Writes to OAMADDR cause corruption of OAM. Leaving OAMADDR at a value of 8 or greater causes OAM corruption when rendering starts.
RP2C02H	no known differences relative to 2C02G.
RP2C03B	RGB PPU, believed standard. OAMDATA and PPU palette are not readable. Color emphasis bits set the corresponding channel to full brightness.
RC2C03B	Believed identical to 2C03B.
RC2C03C	"
RP2C03G	Likely the same core as the 2C02G with the same bugs and features as the 2C02G.
RP2C04-0001	Scrambled palette and new colors, otherwise like 2C03.
RP2C04-0002	"
RP2C04-0003	"
RP2C04-0004	"
RC2C05-01	PPUCTRL and PPUMASK swap locations. Five LSBs of PPUSTATUS return a constant. Otherwise like 2C03.
RC2C05-02	"
RC2C05-03	"
RC2C05-04	"
RP2C07	PAL-B PPU. Vblanking is 71 scanlines long. OAM evaluation can never be fully disabled. Red/green color emphasis swapped.
RP2C07A	Some subtle differences in PPU that make this work better with Kevtris's HDNES, but otherwise believed identical to 2A07.
UA6528	UMC-made clone of 2C02G.
UA6528P	UMC-made variant for PAL-N (Argentina) [1] System crystal is 21492337.5 Hz (exactly 6×15625×229.2516)
UA6538(P??)	UMC-made variant for playing NTSC games in PAL countries. Emits PAL-B video. Vblank IRQ intentionally emitted 50 scanlines later than 2C07. See also Clock rate.
UA6548	UMC-made variant for PAL-M (Brazil) System crystal is 21453671… Hz (exactly 3067875000÷143)
UM6558	UMC-made variant of UA6538 for SECAM countries. Emits 8-bit "Color Data" digital bus, for conversion into SECAM by UA6559 IC. Color palette noticeably off. Maybe supports both 50 and 60 Hz operation?
UM6561	UMC-made NES-on-a-chip. PPU half believed to be identical to UA6538.
TA-02N	??-made clone of UA6528.
TA-02NP	??-made clone of UA6538.
PM02-1	Gradiente-made variant for PAL-M (Brazil). [2]

If you know of other differences or other revisions, please add them!

See also

• Clock rate
• NES_2.0#Byte_13_.28Vs._hardware.29
• https://forums.nesdev.org/viewtopic.php?p=150127#p150127