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VRC7 (not about the sound)
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Author:  Disch [ Sat Dec 04, 2004 5:49 pm ]
Post subject:  VRC7 (not about the sound)

Looking for a VRC7 doc that covers bankswapping regs and other non-sound related operations. Reason being I was going to take a stab at getting a Lagrange Point translation underway since the J2e project seems to be dead. Only VRC7 docs I could find only loosly cover the sound... and Firebug's doc doesn't even touch it at all (or at least I didn't find it anywhere in there).

Any help appreciated

EDIT - I just realized this probably doesn't belong in this forum >_< Whoopsie... sorry about that.

Author:  Quietust [ Sat Dec 04, 2004 7:02 pm ]
Post subject: 

The actual PRG/CHR/etc. mapping logic for the VRC7 can be found in Goroh's KONAMI document. Overall, this is how it works:
$8000 - Select 8KB PRG bank at $8000-$9FFF
$8010 - Select 8KB PRG bank at $A000-$BFFF
$9000 - Select 8KB PRG bank at $C000-$DFFF
$9010/$9030 - sound
$A000 - Select 1KB CHR bank at $0000-$03FF
$A010 - Select 1KB CHR bank at $0400-$07FF
$B000 - Select 1KB CHR bank at $0800-$0BFF
$B010 - Select 1KB CHR bank at $0C00-$0FFF
$C000 - Select 1KB CHR bank at $1000-$13FF
$C010 - Select 1KB CHR bank at $1400-$17FF
$D000 - Select 1KB CHR bank at $1800-$1BFF
$D010 - Select 1KB CHR bank at $1C00-$1FFF
$E000 - Set mirroring (bottom 2 bits = V/H/S0/S1) and SRAM enable (D7:1=enabled, D7:0=disabled)
$E010 - IRQ latch register
$F000 - IRQ control register (D0=$F010 mode, D1=enable, D2=single-cycle vs scanline count)
$F010 - IRQ reset register (sets IRQ enable to $F000 D0)

Note that Lagrange Point uses CHR RAM and that it IS banked.

Tiny Toon Adventures 2 also uses this mapper, though with a few differences - expansion sound is not used, CHR ROM is used rather than CHR RAM, and registers are selected via $X000/$X008 rather than $X000/$X010.

Author:  Disch [ Sat Dec 04, 2004 7:41 pm ]
Post subject: 

Sweeeeet. Thanks a million

Any idea how much CHR-RAM Lagrange Point has? 16k? 32k? more?

Author:  Quietust [ Sat Dec 04, 2004 8:23 pm ]
Post subject: 

Lagrange Point has 8KB of CHR RAM (and 8KB of SRAM), and the mapper supports a total of 512KB of PRG ROM (which the game fully utilizes).

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