INES Mapper 036: Difference between revisions

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(Update description to match FCEUX changes in rev 2776)
(update according to new findings)
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[[Category:iNES Mappers|036]][[Category:GNROM-like mappers|036]]
[[Category:iNES Mappers|036]][[Category:GNROM-like mappers|036]]
[[iNES Mapper 036]] is apparently assigned to the board used some games published by TXC / Micro Genius. This is almost identical to oversize [[GNROM]] with two changes:
[[iNES Mapper 036]] is assigned to TXC's PCB '''01-22000-400''', featuring a 74138, a 74175, and usually a 24-pin ASIC labeled ''05-00002-010''. Three games are currently known to use it, mostly published by Gluk Video:
* As a workaround for incomplete documentation­, FCEUX only listens to writes to the range 0x8000 through 0xFFFE, and
* Strike Wolf
* Reads from $4100 should return the value written to the banking register
* Policeman
* F-15 City War


''Strike Wolf'' writes to unknown registers at $4100-$4103, $4200, and $FFFF.
Even though these games can evidently be emulated as a weird kind of GNROM, the hardware does something quite different:


It's not known what these other registers are supposed to do. Perhaps they're registers internal to the Famiclones made by TXC.
The CHR banking is definitely implemented using the two 7400-series ICs:
Mask: $E200
write $4200: [.... CCCC] - Select 8 KiB CHR bank
 
The PRG banking is part of the ASIC:
Mask: $E103
write $4102 or $8000-$FFFF: [..PP ....] - Request 32 KiB PRG bank
write $4100 then $E103: activate PRG bank switch
read $4100: [..PP ....] - Return current 32 KiB PRG bank
read or write others: ?
 
This PRG reverse-engineering is confusing and incomplete.

Revision as of 22:33, 1 April 2016

iNES Mapper 036 is assigned to TXC's PCB 01-22000-400, featuring a 74138, a 74175, and usually a 24-pin ASIC labeled 05-00002-010. Three games are currently known to use it, mostly published by Gluk Video:

  • Strike Wolf
  • Policeman
  • F-15 City War

Even though these games can evidently be emulated as a weird kind of GNROM, the hardware does something quite different:

The CHR banking is definitely implemented using the two 7400-series ICs: 

Mask: $E200
write $4200: [.... CCCC] - Select 8 KiB CHR bank

The PRG banking is part of the ASIC: 

Mask: $E103
write $4102 or $8000-$FFFF: [..PP ....] - Request 32 KiB PRG bank
write $4100 then $E103: activate PRG bank switch
read $4100: [..PP ....] - Return current 32 KiB PRG bank
read or write others: ?

This PRG reverse-engineering is confusing and incomplete.

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