INES Mapper 101: Difference between revisions

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{{DEFAULTSORT:101}}[[Category:iNES Mappers]][[Category:CNROM-like mappers]][[Category:Bad iNES Mappers]]
{{DEFAULTSORT:101}}[[Category:iNES Mappers]][[Category:CNROM-like mappers]][[Category:Bad iNES Mappers]]
This mapper was allocated for a naïve misdumping of the [http://bootgod.dyndns.org:7777/profile.php?id=1547 JF-10] board that contains ''Urusei Yatsura - Lum no Wedding Bell''. JF-10 is identical to [http://bootgod.dyndns.org:7777/profile.php?id=3004 JF-09], which is the only [[iNES Mapper 087|mapper 87]] game with 32KiB CHR. Both JF-10 and JF-09 only differ from all their predecessors ([http://bootgod.dyndns.org:7777/profile.php?id=3006 JF-05], [http://bootgod.dyndns.org:7777/profile.php?id=2282 -06], [http://bootgod.dyndns.org:7777/profile.php?id=2283 -07], and [http://bootgod.dyndns.org:7777/profile.php?id=1732 -08]) by the addition of a single trace. In short, either mapper 87 should be capped to 16KiB CHR, or mapper 101 never had a hardware instantiation.
This mapper was allocated for a naïve misdumping of the [//nescartdb.com/profile/view/1547 JF-10] board that contains ''Urusei Yatsura - Lum no Wedding Bell'', which assumed the bank bits were reversed. Otherwise, it is entirely identical to [[iNES Mapper 087|J87]].
== Registers ==
=== Bank Select ($6000-$7FFF) ===
This will select an 8 KB CHR ROM bank for PPU $0000-$1FFF.


Supported in r3420 BizHawk, r2696 FCEUX (probably has been supported for eons), and reportedly MESS.
  7  bit 0
   
  ---- ----
  Registers:
CCCC CCHL
  ---------------------------
|||| ||||
  $6000-7FFF: [CCCC CCCC]
|||| |||+- (Normal) Low CHR bit
    C = Selects 8k CHR @ $0000
|||| ||+-- (Normal) High CHR bit
++++-++--- (Oversize only) Extra CHR bits


This is the same as [[iNES Mapper 087|mapper 87]] but with the bits in order, and so has a better defined [[oversize]] extension; or the same as [[CNROM]] without bus conflicts.


Jaleco subsequently extended the JF-09 and JF-10 boards to add the ability to bank PRG in a [[GNROM]]-like manner. That was allocated to [[iNES Mapper 140]].
This is the same as J87 but with the bits in order, and so has a better defined [[oversize]] extension; or the same as [[CNROM]] without bus conflicts.

Latest revision as of 10:17, 25 October 2023

This mapper was allocated for a naïve misdumping of the JF-10 board that contains Urusei Yatsura - Lum no Wedding Bell, which assumed the bank bits were reversed. Otherwise, it is entirely identical to J87.

Registers

Bank Select ($6000-$7FFF)

This will select an 8 KB CHR ROM bank for PPU $0000-$1FFF.

7  bit  0
---- ----
CCCC CCHL
|||| ||||
|||| |||+- (Normal) Low CHR bit
|||| ||+-- (Normal) High CHR bit
++++-++--- (Oversize only) Extra CHR bits


This is the same as J87 but with the bits in order, and so has a better defined oversize extension; or the same as CNROM without bus conflicts.