INES Mapper 101: Difference between revisions

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This mapper is used for instance by Urusei Yatsura - Lum no Wedding Bell.
{{DEFAULTSORT:101}}[[Category:iNES Mappers]][[Category:CNROM-like mappers]][[Category:Bad iNES Mappers]]
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:
== Registers ==
---------------------------
=== Bank Select ($6000-$7FFF) ===
  $6000-7FFF: [CCCC CCCC]
This will select an 8 KB CHR ROM bank for PPU $0000-$1FFF.
    C = Selects 8k CHR @ $0000


It's unknown how many bits C is but it probably isn't 8.
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.

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.