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PostPosted: Thu Aug 04, 2005 3:53 pm 
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Formerly Fx3
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Posts: 3076
Location: Brazil
Well, about the VBlank flag, it might take conclusions about its effect on emulation - like if the ppu frame cannot start on VINT, OR in the scanline right before the scanline #0. I've read about starting at VINT, then starting at scanline -1... and that it doesn't even matter... ^_^;; This would require a verification on real hardware.

The NES has a lot of quirks that I'm impressed...

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PostPosted: Thu Aug 04, 2005 3:55 pm 
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Posts: 3715
Location: Central Texas, USA
hap wrote:
Kamen Rider Club (J) doesn't like that (locks up).


Either that or it doesn't like something else, but was content when this wasn't emulated correctly? Or maybe it's different on the Famicom.

One thing that would help with reverse-engineering efforts is data on what games actually do at power-up. In this case, if any of them try reading before the noted time (obviously Kamen Rider Club (J) does).

Also, the only way to really be sure an emulator is implementing things as specified is to write test ROMs for a given feature. Maybe I'll do that tonight for these power-up features.


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PostPosted: Thu Aug 04, 2005 4:34 pm 
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Kamen Rider Club (J):
- disables nmi, reads 0x2002.7 (set at boot)
- reads 0x2002.7 again (set at vblank)
- initialize (banking and such)
- while still in vblank:
Code:
cpu prgbank3read ad: ef51(f51) data: a9
cpu prgbank3read ad: ef52(f52) data: c
a9 LDA Immediate PC:ef51 A:c X:ff Y:f P:001B0100 ad:ef52

cpu prgbank3read ad: ef53(f53) data: 8d
cpu prgbank3read ad: ef54(f54) data: 6
cpu prgbank3read ad: ef55(f55) data: 20
8d STA Absolute PC:ef53 A:c X:ff Y:f P:001B0100 ad:2006

cpu prgbank3read ad: ef56(f56) data: a9
cpu prgbank3read ad: ef57(f57) data: 45
a9 LDA Immediate PC:ef56 A:45 X:ff Y:f P:001B0100 ad:ef57

cpu prgbank3read ad: ef58(f58) data: 8d
cpu prgbank3read ad: ef59(f59) data: 6
cpu prgbank3read ad: ef5a(f5a) data: 20
8d STA Absolute PC:ef58 A:45 X:ff Y:f P:001B0100 ad:2006

cpu prgbank3read ad: ef5b(f5b) data: ad
cpu prgbank3read ad: ef5c(f5c) data: 7
cpu prgbank3read ad: ef5d(f5d) data: 20
ad LDA Absolute PC:ef5b A:0 X:ff Y:f P:001B0110 ad:2007

cpu prgbank3read ad: ef5e(f5e) data: ad
cpu prgbank3read ad: ef5f(f5f) data: 7
cpu prgbank3read ad: ef60(f60) data: 20
ad LDA Absolute PC:ef5e A:0 X:ff Y:f P:001B0110 ad:2007

cpu prgbank3read ad: ef61(f61) data: d9
cpu prgbank3read ad: ef62(f62) data: 76
cpu prgbank3read ad: ef63(f63) data: ef
cpu prgbank3read ad: ef85(f85) data: 33
d9 CMP Indexed Absolute (Y) PC:ef61 A:0 X:ff Y:f P:101B0100 ad:ef85

cpu prgbank3read ad: ef64(f64) data: d0
cpu prgbank3read ad: ef65(f65) data: 5
d0 BNE Relative PC:ef64 A:0 X:ff Y:f P:101B0100 ad:ef6b

(does the JMP forever)
cpu prgbank3read ad: ef6b(f6b) data: 4c
cpu prgbank3read ad: ef6c(f6c) data: 6b
cpu prgbank3read ad: ef6d(f6d) data: ef
4c JMP Absolute PC:ef6b A:0 X:ff Y:f P:101B0100 ad:ef6b


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