Search found 1135 matches

by nocash
Thu Feb 27, 2020 11:57 am
Forum: Other Retro Dev
Topic: 3DS reverse engineering
Replies: 197
Views: 105956

Re: 3DS reverse engineering

3. Certain titles may have 0x25, 0x1b, 0x18, or 0x2c -- it really doesn't seem to follow any logical pattern. It does appear that new3ds mcu module changed from 0x2c -> 0x1b at some point (probably the new2xl update version 9216, or firm 11.4/11.5). Old3ds has always been 0x2c. Good to know. Hmmm, ...
by nocash
Thu Feb 27, 2020 10:46 am
Forum: Other Retro Dev
Topic: DSi unlaunch (bootcode exploit)
Replies: 191
Views: 152738

Re: DSi unlaunch (bootcode exploit)

Which homebrews are that? And are the binaries available for download somewhere?
by nocash
Tue Feb 25, 2020 7:06 pm
Forum: Other Retro Dev
Topic: 3DS reverse engineering
Replies: 197
Views: 105956

Re: 3DS reverse engineering

I have finally brewed up some code for loading/decrypting/decompressing .code files from eMMC, the current purpose would be loading the original MCU firmware before patching. It's working okay, but I could imagine a few possible problems: 1) I am ignoring the .tmd/.cmd files, and just load "ncsd:\ti...
by nocash
Tue Feb 25, 2020 5:02 pm
Forum: SNESdev
Topic: Need sound help emulating NES on SNES
Replies: 29
Views: 14673

Re: Need sound help emulating NES on SNES

I've heard of a bug that combines (same as logical OR) the data on those ports if it is being read on one side at the same time the other side is writing to it. So for port 0, I may use bit 6 to be the opposite of bit 7. Yes, that hardware bug is documented for APU to SNES direction (not sure if it...
by nocash
Wed Feb 19, 2020 2:58 pm
Forum: NESdev
Topic: divide by 10
Replies: 4
Views: 432

Re: divide by 10

Makes me wonder if there are other ways... here are some untested ideas: Multiply by 25.6 would also work, or easier, multply by 25.5 with some rounding fix. But that would take about 81 cycles, too... mov x,0 ;2 ;\msb mov [v1+1],x ;3 ;/ mov [v0],a ;3 ;-A*1 shl a ;2 ;\ rcl [v1+1] ;5 ; shl a ;2 ; A*8...
by nocash
Mon Feb 17, 2020 3:43 pm
Forum: SNESdev
Topic: Hardware-implementable emulator inaccuracies
Replies: 3
Views: 400

Re: Hardware-implementable emulator inaccuracies

VRAM writes won't need to stall anything, assuming that modern RAM is fast enough to complete read & write in "one cycle". But it's not so much of a good idea to try to overcome the original hardware restrictions & to encourage people to make games that are incompatible with original hardware ... un...
by nocash
Sun Feb 16, 2020 6:46 pm
Forum: Other Retro Dev
Topic: 3DS reverse engineering
Replies: 197
Views: 105956

Re: 3DS reverse engineering

I've found the MCU ROM , and dumped it today. It's enabled via the writes to FLPMC (those with value 1Dh do enable it, and those with 0Ch do hide it again). There is 10Kbyte of ROM at ED800h..EFFFFh, and another 1.5Kbyte of ROM at F0800h..F0DFFh (plus a weird 0.5Kbyte RAM mirror at F0E00h..F0FFFh th...
by nocash
Fri Feb 14, 2020 2:54 pm
Forum: SNESdev
Topic: I wrote up a "brief" explainer on SNES cartridges
Replies: 19
Views: 2921

Re: I wrote up a "brief" explainer on SNES cartridges

I am afraid that I had misread this sentence "On every SNES board you’ll notice a handful of capacitors." I had interpreted it as referring to the mainboard, but now I think that it does refer to the cartridge board... and then the description makes much more sense than I had thought : )
by nocash
Fri Feb 14, 2020 10:07 am
Forum: SNESdev
Topic: I wrote up a "brief" explainer on SNES cartridges
Replies: 19
Views: 2921

Re: I wrote up a "brief" explainer on SNES cartridges

Pedantically, it's so that varying currents drawn by the SNES and cartridge don't cause varying voltages. More pedantically, it's actually probably both No, that's nonsense the SNES does draw (consume) power, it does not supply (generate) power. Also, the capacitor that you are talking about is the...
by nocash
Thu Feb 13, 2020 8:25 pm
Forum: SNESdev
Topic: Jump exection code to RAM
Replies: 6
Views: 806

Re: Jump exection code to RAM

Technically it is trivial, and more so because it can be tested in snes debuggers. The main problem would be to figure out how to tweak your assembler or compiler to assign ram addresses for relocated code/data. And of course, knowing how to memcopy code from rom to ram. And some good understanding ...
by nocash
Wed Feb 12, 2020 6:35 pm
Forum: SNESdev
Topic: Jump exection code to RAM
Replies: 6
Views: 806

Re: Jump exection code to RAM

But why? Using code in RAM only makes sense if you were using self-modifying code (which is unlikely in C), or if you want to artifically slowdown a fast ROM cartridge to slow RAM timings (makes no sense at all), or when removing the ROM cartridge.
by nocash
Tue Feb 11, 2020 9:56 pm
Forum: Other Retro Dev
Topic: 3DS reverse engineering
Replies: 197
Views: 105956

Re: 3DS reverse engineering

I've meanwhile tested reflashing via normal I2C commands. Patching the hardcoded delay settings worked without problems. Adding the hook function for switching power-led to purple upon holding the button did also work without problems. And the hook for executing custom code in ram... that was a bit ...
by nocash
Mon Feb 10, 2020 9:39 am
Forum: Other Retro Dev
Topic: 3DS reverse engineering
Replies: 197
Views: 105956

Re: 3DS reverse engineering

Got it unbricked. The transfer timing got 100% stable after using a "cli" opcode to disable interrupts. For the erase/write commands, the parameters can be used to specify any length, but they seem to be working for max 1000h bytes only (don't know why, it's an odd limit because that would be four ...
by nocash
Sun Feb 09, 2020 8:25 pm
Forum: Other Retro Dev
Topic: 3DS reverse engineering
Replies: 197
Views: 105956

Re: 3DS reverse engineering

I am seeing the bricking more positive, it seems that the data has been written successfully from first timestamp, up to including the last timestamp at the end of the firmware image (otherwise the brick wouldn't have occured), so I think that I have proven tbat writing isn't a problem at all. The o...
by nocash
Fri Feb 07, 2020 3:14 pm
Forum: Other Retro Dev
Topic: 3DS reverse engineering
Replies: 197
Views: 105956

Re: 3DS reverse engineering

Sorry. I should have said language barrier in general. I somewhat got the console donated as "the gui supports japanese only but you can take apart the mainboard for hacking if you want to have it". The region lock is also part of the reason why I've never had any gaming experience on that console, ...