NES 2.0 submappers/Proposals: Difference between revisions

Latest revision as of 19:09, 18 January 2023

This page collects proposals for NES 2.0 submappers that are not yet ready for implementation.

Explain what game or ROM is incompatible with existing submappers.
Explain how the proposed submapper should be implemented.
Allow one or more other members of the community to independently verify that both 1 and 2 are correct. (We'll perform peer review, commentary, and possible revision/iteration here.)
Allocate and document the new submapper, listing the relevant game/ROM.

When allocating new submappers, please consult kevtris' original proposal before choosing a number. If it is something he already assigned that we have just not adopted yet, use his existing assignment: submappers.txt

If there is no existing game or ROM that requires a submapper, it should not yet be allocated. There is no end to possible variations of hardware, and there is no need to speculate on the future. If you want to work on a project that will require a new mapper, engage the community and/or seek help from others. Do not pre-emptively add a new mapper to the spec until there is something we can run with it. The spec will still be here when you're finished your project.

005: MMC5

Status: MMC5A is unimplemented in emulators, and all existing games are also valid as MMC5. Seems to be de-facto low priority.

005: 0

MMC5

005: 1

MMC5A

MMC5A is a known variant of the chip with some added features. However, all existing games with MMC5A also appear to have existed with MMC5. Nothing deliberately uses these features, but behaviour of a bug could differ by the selected chip.

Bitfield Wishlist

A previous proposal included this wishlist to use it as a bitfield for other mapper configurations that were never used in games. With the discovery of MMC5A variations, there can no longer enough bits to accommodate all of these.

Vertical split mode:
0: SL (all known hardware)
1: CL

If only one kind (battery or non-battery) of PRG-RAM present:
0: PRG-RAM is contiguous (EKROM, EWROM)
2: PRG-RAM is not contiguous; is split in half across two chips

If both kinds of PRG-RAM present:
0: Chip 0 is battery-backed (ETROM (note: verify this))
4: Chip 1 is battery-backed

Pulse waves volume:
0: R1 is 6.8kΩ (as in all games that use expansion audio)
8: R1 is 15kΩ (the nominal value of this resistor)

070: Bandai UNROM/GNROM hybrid

Status: Problem outline, needs followup?

There is a report of a pirate copy of a game that seems to want mapper 70 without bus conflicts, even though Bandai's original hardware should have them.

Tentatively, we could use the same submappers as those standardized for mappers 2, 3, & 7.

083: Cony

Status: Needs documentation of affected games and implementation testing.

"There's actually three different versions of the hardware, all assigned to the same mapper. Unfortunately, we have no idea which is which."

Kevtris's assignments:

083: 0

"Bog-standard Cony mapper. 1K CHR ROM banks, no WRAM."

083: 1

"Same, but with 2K CHR ROM banks instead."

083: 2

"This is the standard Cony mapper with the following changes:

1K CHR ROM banks (like 83.0)

a 4 bit 256K CHR/PRG bank select register:
- B000h: bits 6 and 7 select the 256K superbank

1 byte of RAM at 5103h (stores the last game played) Game will not start without this RAM byte.

WRAM at 6000-7FFFh. WRAM is banked with the PRG/CHR superbank. This gives a total of 32K. It is battery backed.

086: Jaleco JF-13

Status: Needs documentation of behaviour differences and chip emulation, a way to dump sample data for emulatable ROMs, and relevant games.

There is a bootleg variant that uses a UM5100 (DPCM) instead of µPD7756C (ADPCM).

086: 0

Uses µPD7756C (Standard).

086: 1

Uses UM5100 (Bootleg).

References

Atari Age forum post - Kevtris' Analogue NT Mini firmware notes including a slightly updated submapper list.

@@ Line 11: / Line 11: @@
 == 005: [[MMC5]] ==
-Status: Wishlist
+Status: MMC5A is unimplemented in emulators, and all existing games are also valid as MMC5. Seems to be de-facto low priority.
+=== 005: 0 ===
+MMC5
+=== 005: 1 ===
+MMC5A
+MMC5A is a known variant of the chip with some added features. However, all existing games with MMC5A also appear to have existed with MMC5. Nothing deliberately uses these features, but behaviour of a bug could differ by the selected chip.
+=== Bitfield Wishlist ===
+A previous proposal included this wishlist to use it as a bitfield for other mapper configurations that were never used in games. With the discovery of MMC5A variations, there can no longer enough bits to accommodate all of these.
 Vertical split mode: <br>
@@ Line 23: / Line 36: @@
 If both kinds of PRG-RAM present: <br>
 : Chip 0 is battery-backed (ETROM (note: verify this)) <br>
 : Chip 1 is battery-backed <br>
 Pulse waves volume: <br>
 : R1 is 6.8kΩ (as in all games that use expansion audio) <br>
 : R1 is 15kΩ (the nominal value of this resistor) <br>
-It is safe to leave the submapper number at 0 for all known games.
-== 002, 003, 007: [[UxROM]], [[CNROM]], [[AxROM]] ==
-Status: Draft
-AxROM (mapper 7) is the only known licensed discrete logic mapper to unreliably come with [[bus conflict]] prevention circuitry. While no game documented in NesCartDB was released in one region on multiple board variants, several games did change boards when localized.
-The following table is tentatively offered-<br>
-: Normal (No advisory statement is made as to whether this game has bus conflicts) (uninvestigated AOROM) <br>
-: Bus conflicts do not occur (ANROM) <br>
-: Bus conflicts occur (AMROM)
-Although all Nintendo-manufactured games using normal CNROM (mapper 3), normal UxROM (mapper 2), and inverted UxROM (mapper 180) had bus conflicts, apparently several unlicensed games require their absence, as does the updated version of ''Donkey Kong'' with the pie factory level.[http://www.nintendoage.com/forum/messageview.cfm?catid=22&threadid=44613] This same table should be used for them, too.
-CNROM with security diodes (mapper 185) has a different set of submapper definitions.
-== 019: Namco 129 and 163 ==
+== 070: Bandai UNROM/GNROM hybrid ==
-Status: Problem outline
+Status: Problem outline, needs followup?
-[[iNES Mapper 019|Mapper 19]] designates the [[Namco 163|Namco 129 and 163]], which supports [[Namco 163 audio|expansion sound]], IRQs, and ROM nametables.
+There is [https://forums.nesdev.org/viewtopic.php?t=16916 a report] of a pirate copy of a game that seems to want mapper 70 without bus conflicts, even though Bandai's original hardware should have them.
-Different 163-using PCBs used a different resistor to change the volume of the expansion audio relative to the internal 2A03 audio. It is unclear if this variation warrants a submapper.
+Tentatively, we could use the same submappers as those standardized for mappers 2, 3, & 7.
-KH allocated a submapper specifically for the N163-using game Mindseeker. It is not known what is different about this game.
+== [[iNES Mapper 083|083]]: Cony ==
+Status: Needs documentation of affected games and implementation testing.
-Tentative suggestion:<br/>
+"There's actually three different versions of the hardware, all assigned to the same mapper. Unfortunately, we have no idea which is which."
-Mapper 19:<br/>
-: N163, expansion audio unused (mixing resistor: 0Ω)<br/>
-: N163, mixing resistor:  4.7kΩ<br/>
-: N163, mixing resistor: 10kΩ<br/>
-: N163, mixing resistor: 15kΩ<br/>
-: N129. Expansion audio is known buggy relative to N163, but other differences are not known.<br/>
-Source: [http://blog.kevtris.org/blogfiles/nes/submappers.txt KH's submappers]
+Kevtris's assignments:
+=== 083: 0 ===
+"Bog-standard Cony mapper.  1K CHR ROM banks, no WRAM."
-== 021, 023, 025: VRC4 ==
+=== 083: 1 ===
-Konami's [[VRC4]] mapper has five known variations of how the board connects low CPU address lines among A7-A0 to the port select lines of the mapper.
+"Same, but with 2K CHR ROM banks instead."
-These are spread across three mappers: two for [[iNES Mapper 021|21]], two for [[iNES Mapper 025|25]], and one for [[iNES Mapper 023|23]].
-There are theoretically 8*7 = 56 ways to wire these, but in all five extant possibilities, two adjacent address lines are used: A2 and A1, A0 and A1, A7 and A6, A2 and A3, and A3 and A2.
-All 14 combinations of two adjacent address lines easily fit in a submapper number:
-<pre>
-||||
-|+++- Which address line corresponds is wired to the A1 in the VRC4a
-+---- 0: Use next lower address line for VRC4a A2; 1: use next higher line
-</pre>
-The values 0 (A0 and next lower) and 15 (A7 and next higher) are impossible.
-The [[VRC4]] article describes the ports by mapping them to the variant called "VRC4a" on that page, which uses A2 and A1, putting the four [[VRC IRQ]] ports (IRQ Latch low, IRQ Latch high, IRQ Control, and IRQ Acknowledge) at $F000, $F002, $F004, and $F006.
+=== 083: 2 ===
-{| class="tabular"
+"This is the standard Cony mapper with the following changes:
-! Nickname || A2 || A1 || Registers || iNES mapper || NES 2.0 submapper
-|-
-| VRC4a || A2 || A1 || $x000, $x002, $x004, $x006 || 21 || 9
-|-
-| VRC4b || A0 || A1 || $x000, $x002, $x001, $x003 || 25 || 1
-|-
-| VRC4c || A7 || A6 || $x000, $x040, $x080, $x0C0 || 21 || 14
-|-
-| VRC4d || A2 || A3 || $x000, $x008, $x004, $x00C || 25 || 3
-|-
-| VRC4e || A3 || A2 || $x000, $x004, $x008, $x00C || 23 || 10
-|}
-== 023, 025: VRC2 ==
+# 1K CHR ROM banks (like 83.0)
-Mappers [[iNES Mapper 023|23]] and [[iNES Mapper 025|25]] are used for both Konami's [[VRC2]] and VRC4.
-It is tentatively suggested that submapper 15 (invalid per the VRC4 definitions) be used to mark VRC2-using games, to handle the bit at $6000 and lack of interrupts.
-Neither divides CHR bank select by two, unlike [[INES Mapper 022|#22]].
-* 23.15 is VRC2 ($xxx0, $xxx1, $xxx2, $xxx3)
-* 25.15 is VRC2 ($xxx0, $xxx2, $xxx1, $xxx3)
-== [[iNES Mapper 034|034]]: [[BNROM]] / [[NINA-001]] ==
+# a 4 bit 256K CHR/PRG bank select register:
-This iNES mapper unfortunately combines the unrelated [[BNROM]] and [[NINA-001]] mappers.
+#* B000h:  bits 6 and 7 select the 256K superbank
-=== 034: 0 ===
+# 1 byte of RAM at 5103h (stores the last game played) Game will not start without this RAM byte.
-Normal. Both mappers can be implemented simultaneously without incompatibility.
-Because the NINA-001 supports CHR banking and BNROM does not, the presence of more than 8 KiB of CHR implies NINA-001, and could be used to select between two exclusive mapper implementations.
+# WRAM at 6000-7FFFh.  WRAM is banked with the PRG/CHR superbank.  This gives a total of 32K.  It is battery backed.
-=== 034: 1 ===
+== [[iNES Mapper 086|086]]: Jaleco JF-13 ==
-NINA-001 only.
+Status: Needs documentation of behaviour differences and chip emulation, a way to dump sample data for emulatable ROMs, and relevant games.
-* ''(no extant games require this)''
-== [[iNES Mapper 185]] ==
+There is a bootleg variant that uses a UM5100 (DPCM) instead of µPD7756C (ADPCM).
-Status: Draft
-A few NROM-like games were released on CNROM boards where all four bits of the latch were solely used as an anti-piracy measure. While a documented heuristic exists for which values were used, we tentatively suggest that the submapper here indicate the value to be written to the latch for normal operation (<tt>submapper = (latch&0x30)/4+(latch&3)</tt>)
+=== 086: 0 ===
+Uses µPD7756C (Standard).
-<pre>
+=== 086: 1 ===
+Uses UM5100 (Bootleg).
-||||
-|||+- Bit 0 (bank number)
-||+-- Bit 1 (bank number)
-|+--- Bit 4 (diode config)
-+---- Bit 5 (diode config)
-</pre>
-In the case that any of the bits are "don't care", use 0.
+== References ==
+<references />
+* [http://atariage.com/forums/topic/242970-fpga-based-videogame-system/?p=3687219 Atari Age forum post] - Kevtris' Analogue NT Mini firmware notes including a slightly updated submapper list.

NES 2.0 submappers/Proposals: Difference between revisions

Latest revision as of 19:09, 18 January 2023

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