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Nice work, looks to be quite a nice test rom! Does it check CHR-ROM bank size of 2KB with VRCIIa compared to 1KB of VRCIIb/c? Is that what the CHR A10 test is denoting? The bank size is the same (eight banks of 1KB) but the bank numbers are effectively right-shifted 1 place, so you have to write n ...

The following are WIP screenshots of a VRC2/4 test program. All three screenshots are the exact same ROM with different iNES headers, running in FCEUX current SVN (r3372). vrctest21-0.png vrctest22-0.png vrctest4-0.png Briefly, the test program probes the connections of pins 3, 4 and 21 by writing v...

Hi, I can't seem to find information regarding how 0xCB instructions are handled by the CPU when it comes to the Timer and Interruptions. Meaning, is the 0xCB read as an instruction and then handles things etc, then it reads then ext instruction from the 0xCB table. Or is 0xCB read and immediately ...

While working on that VRC2/4 submapper test ROM, I just noticed that FCEUX doesn't emulate the simple cycle-counting mode (without the 113 2/3 cycle divider) for any of VRC4, VRC6 or VRC7. Bit 0x04 of the relevant register is completely ignored. Also, an 8-bit cycle counter just doesn't seem very us...

Myask wrote:

CA | NOT | 0 | left = !left
CB | MINUS | 0 | left = -left
CC | COMPL | 0 | left = ~left

with all three existing, I'm curious what NOT does. Is it LEFT = (LEFT[15:0] ==0 ? 1 : 0)?

Yes.

Hmm, well my method was to just do precisely as the Table said, with a ton of If/Else, but there are some cases which just doesn't exist, which you might be talking about. I tried the code you linked and it works. Though i am a bit confused how. I have read up on BCD, and i get the principle of it,...

Thogart wrote:I have successfully dumped about half my carts...

I'll have to drag out my system and see if the cart still works...
Could that batt just be dead?

The battery wouldn't affect dumping (or playing) the cartridge.

Dump #1 anago>anago.exe D mmc1_slrom.ad Link.nes program 0x000000:01 4b 0a c0 ca c6 ce c4-c4 c8 cf ce cb 01 c8 0f:0x15333c program 0x004000:01 4b 0a c0 ca c6 ce c4-c4 c8 cf ce cb 01 c8 0f:0x15333c program 0x008000:01 4b 0a c0 ca c6 ce c4-c4 c8 cf ce cb 01 c8 0f:0x15333c program 0x00c000:01 4b 0a c0...

If two of the same enemy are in the same RNG-tapping state on the same frame then they'll always both choose the same behaviour I've seen that in several games, and I've always thought of it as a serious flaw, not something people hardly notice. :P I've often been annoyed at how unintentionally pre...

In an action game where cycles are precious, an advantage of a LFSR over a LCG is that all the bits in a LFSR are equally random. If you only ever need one or two bits at a time, you can get many random numbers out of each clocking of a LFSR. Super Mario Bros. and Kung Fu Heroes use a 64-bit LFSR wh...

Maybe a KISS RNG would be worth using for high quality numbers. Some variants don't use multiplication. /* Implementation of a 32-bit KISS generator which uses no multiply instructions */ static unsigned int x=123456789,y=234567891,z=345678912,w=456789123,c=0; unsigned int JKISS32() { int t; y ^= (...

From that thread: why you don't usually want to use an LCG for generating X,Y pairs The Dragon Ball/Dragon Ball Z RPGs programmed by TOSE on the NES use an 8-bit LCG. Which they cripple further by always using the low-order bits, the least random ones in any LCG. And the main use of those random num...

Dragon Warrior 2 & 3 used a LFSR (linear feedback shift register) for the RNG. They also happened to use the same bytes of memory to store the saved game checksum. Some save checksums will freeze the RNG. It's more accurate to say that they use the same code both as a PRNG and as a CRC16 calcul...

^^^ I guess you just volunteered? Bitfields There are three bitfield instructions: one to extract (load from) a signed bitfield, one to extract an unsigned bitfield, and one to insert (store to) a bitfield. For all three bitfield instructions, the first byte after the instruction is the size of the...

I can write a test program if someone has cartridge(s) they can EPROM-ize.