PPU variants
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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. |
| RP2C03C | RGB PPU, believed standard. A newer revision. |
| RC2C03B | Believed identical to 2C03B. But there is an evidence that it has a bit different palette. |
| RC2C03C | Believed identical to 2C03C. |
| RP2C03G | No photos on the internet, probably does not exist. If exists, 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 | " |
| RC2C05-99 | Approximately equivalent to some 2C03. Used in the Famicom Titler. Behavior of five LSBs of PPUSTATUS unknown. (picture of Titler PCBs) |
| RP2C07 | PAL-B PPU. Vblanking is 71 scanlines long. OAM evaluation can never be fully disabled. Red/green color emphasis swapped. OAMADDR works correctly, not corrupting OAM contents. |
| 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. |
| UA6541 | UMC-made clone of 2C07 [2] |
| 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? |
| UM6561xx-1 | UMC-made NES-on-a-chip for NTSC. PPU half believed identical to UA6528. Revisions "xx" AF, BF, CF, F known. |
| UM6561xx-2 | UMC-made NES-on-a-chip for PAL-B. PPU half believed to be identical to UA6538. Revisions "xx" AF, BF, CF, F known. |
| TA-02N | ??-made clone of UA6528. |
| TA-02NP | ??-made clone of UA6538. |
| T1818 | ??-made NES-on-a-chip, NTSC timing. Believed to exist, but evidence currently scant. |
| T1818P | ??-made NES-on-a-chip.[3]. Requires external 2KiB RAMs for CPU and PPU. UA6538 timing. |
| PM02-1 | Gradiente-made variant for PAL-M (Brazil). [4] |
| VT01 | V.R.Tech-made clone of UA6561. Only seen as chip-on-board. Supports composite out; RGB out; or 2bpp STN LCD, either greyscale or red/cyan checkerboard, 240 px wide, 80/120/160/240px tall. The chip was extended significantly in VT02 and newer NOACs. |
If you know of other differences or other revisions, please add them!
