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PostPosted: Mon Jun 06, 2005 1:10 pm 
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Martin Korth, the author of NO$GMB and NO$GBA, appears to have started on an emulator called NO$NES that aims to implement the virtual machine specified by this document. Can anybody find any differences in behavior between that document and what we know about the Famicom or NES?

I've already found one: the description of "Sprite 0 Hit Flag" ($2002.d6) fails to mention that it doesn't become set if the overlap happens either at x=255 or at x=0..7 (if either or both of the clipping bits of $2001 are 0).

The description of MMC3 IRQs in "Cartridge IRQ Counters" might be wrong.


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PostPosted: Mon Jun 06, 2005 2:03 pm 
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I have about as much interest in a no-cash emu as I do in iNES:

zip

I'm sure it will fall short to existing emus -- and will have a pricetag to boot. And I sincerely doubt its debugger will be on par with FCEUXD's.


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PostPosted: Mon Jun 06, 2005 3:25 pm 
Have anyone investigated exactly what happens when doing a sprite DMA transfer?

Will a DMA start from current OAM-address, or will it start from the beginning of memory as I've heard?

In the document it mentions 512 cycles, no room for setting the address.

Another one:
"the DMC will halt the CPU for 2 clock cycles to retrieve the next sample-byte"
I've heard four cycles.


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PostPosted: Mon Jun 06, 2005 5:46 pm 
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I just don't understand why people make yet another composite of NES information, when it's incomplete and thus subject to update. It's yet another collection of information that will be out of date, with perhaps some new information mixed in, more hay to search through for needles. About the only useful thing to do is keep an index of links the most up-to-date information.

Whenever I get around to finishing my APU reverse-engineering, the result will be test ROMs and the result when run on a NES (i.e. raw data) and asm source, an interpretation of the data (open to scrutiny), and an emulator which passes the tests.


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PostPosted: Mon Jun 06, 2005 6:33 pm 
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In other words, this one would be a second NESticle, am I right? :P
For some reason, I cannot access his website. :|

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PostPosted: Mon Jun 06, 2005 7:23 pm 
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Are you talking about that Nesticle runs in DOS, that Nesticle includes a built-in CHR ROM editor, or that Nesticle is hella-inaccurate? At least NO$GMB and NO$GBA strive for accuracy, though some versions do run in DOS, and the paid versions include debugging tools.


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PostPosted: Mon Jun 06, 2005 8:46 pm 
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blargg wrote:
I just don't understand why people make yet another composite of NES information, when it's incomplete and thus subject to update. It's yet another collection of information that will be out of date, with perhaps some new information mixed in, more hay to search through for needles. About the only useful thing to do is keep an index of links the most up-to-date information.

Whenever I get around to finishing my APU reverse-engineering, the result will be test ROMs and the result when run on a NES (i.e. raw data) and asm source, an interpretation of the data (open to scrutiny), and an emulator which passes the tests.


nesdev should host a database of stress test ROMs. It is typically considered a good software development practice to have a collection of regression test data/programs that you can run your piece of software against to test for common or known issues. There are a few stress test ROMs in the GoodNES collection, but I think there are a few that have been left out. I am sure that some stress testers haven't even been tested on a real NES, which is a problem, but even then, any emul author could pop a stress test ROM in their NES, if they have a Squeedo or EPROM programmer and dev cart.


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PostPosted: Mon Jun 06, 2005 10:44 pm 
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Jagasian wrote:
nesdev should host a database of stress test ROMs.

Agreed, as long as they've been tested on Nintendo brand hardware.

Quote:
but even then, any emul author could pop a stress test ROM in their NES, if they have a Squeedo or EPROM programmer and dev cart.

Who could afford to put together a dev cart for each of 255 iNES board class numbers (even collapsing NROM and CNROM into one class)?


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PostPosted: Tue Jun 07, 2005 6:26 am 
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tepples wrote:
Are you talking about that Nesticle runs in DOS, that Nesticle includes a built-in CHR ROM editor, or that Nesticle is hella-inaccurate? At least NO$GMB and NO$GBA strive for accuracy, though some versions do run in DOS, and the paid versions include debugging tools.


CHR/NAM viewer does not promote accuracy. This new emu brings information that SUPPOSELY is inaccurate, or does not match what we know about the NES/Famicom. I did a comparision with NESticle because of this. Plus, if you still love NESticle, you're evil. :P

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PostPosted: Tue Jun 07, 2005 2:57 pm 
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I'm not a nesticle fan either.

If the information in Martin Korth's document is inaccurate, then please post the inaccuracies here or e-mail them to Martin Korth rather than flaming him or me.


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PostPosted: Tue Jun 07, 2005 3:26 pm 
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I'm not flaming... I'm in the business too since 1998. Besides, I would be the last one to report an innacuracy, since I'm not the guru here. :P Indeed, I only read what was posted here and... well, enough.

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