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1 | FCE Ultra General User's FAQ |
2 | preliminary version |
3 | ------------------ |
4 | |
5 | |
6 | Q: Why doesn't the NSF <insert name here> work(correctly) on FCE Ultra? |
7 | A: Some NSF rips are bad. Some read from addresses that are not specified |
8 | in the NSF specifications, expecting certain values to be returned. |
9 | Others execute undocumented instructions that have no affect on |
10 | less-accurate software NSF players, but will cause problems on NSF players |
11 | that emulate these instructions. Also, the playback rate specified |
12 | in the NSF header is currently ignored, though I haven't encountered |
13 | any problems in doing this. |
14 | |
15 | |
16 | Q: Why doesn't the game <insert name here> work(correctly) on FCE Ultra? |
17 | A: Many factors can make a game not work on FCE Ultra: |
18 | |
19 | - If the ROM image is in the iNES format(typically files that have |
20 | the extension "nes"), its header may be incorrect. This |
21 | incorrectness may also be because of garbage in the |
22 | header. Certain utilities used to put text in the reserved |
23 | bytes of the iNES header, then those reserved bytes were |
24 | later assigned functions. FCE Ultra recognizes and |
25 | automatically removes(from the ROM image in RAM, not on the |
26 | storage medium) SOME header junk. |
27 | |
28 | If the game has graphical errors while scrolling, chances are |
29 | the mirroring is set incorrectly in the header. |
30 | |
31 | You can try to edit the header with a utility(in the NES |
32 | utilities section at http://zophar.net ) or a hex editor. |
33 | |
34 | - The on-cart hardware the game uses may not be emulated |
35 | correctly. |
36 | |
37 | - Limitations of the ROM image format may prevent a game from |
38 | being emulated correctly without special code to recognize that |
39 | game. This occurs quite often with many Koei MMC5(iNES mapper 5) |
40 | and MMC1(iNES mapper 1) games in the iNES format. FCE Ultra identifies |
41 | and emulates some of these games based on the ROM CRC32 value. |
42 | |
43 | - The ROM image may be encrypted. The author of SMYNES seems to |
44 | have done this intentionally to block other emulators from |
45 | playing "SMYNES only" games. |