readme.txt

著名SFC模拟器Snes9x的源代码。

Many SNES games could take a very long time to complete from start to finish
so they allowed your progressed to be saved into RAM fitted inside the game
pack; the RAM contents were backed up by a battery when the SNES was switched
off or the game removed. Snes9x simulates this by saving the contents of the
emulated battery-backed RAM into a file when you load a new game or exit
Snes9x. The file is then automatically re-loaded the next time you play the
game.

Snes9x also provides freeze-files; these are files that saves a game's
position at any point in the game, not just at predefined places chosen by the
game's designers - ideal for saving your game just before a tricky bit!
Snes9x provides 9 save slots; during a game, press Shift + F1 to F9 to save a
game, and just F1 to F9 to load it again later.

Freeze game files and Save-RAM (S-RAM) save files are normally read from and
written to the directory $HOME/.snes96_snapshots. This can be changed by
setting the environment variable SNES96_SNAPSHOT_DIR to point to a different
directory.

Snes9x uses its own unique format for freeze-files, as does ZSNES, but Snes9x
can also load ZSNES format freeze-files. Just copy the ZSNES freeze files into
your save directory and, if the native format Snes9x freeze file doesn't exist
(<rom image name>.00X where X is a digit), Snes9x will try to load the
corresponding ZSNES freeze file instead (<rom image name>.zsX where X is a 't'
or a digit). Note the filename extension must be in lower-case. When you
freeze a game position after loading a ZSNES format freeze file, Snes9x will
save it in native Snes9x format.

Netplay Support
===============

Netplay support is currently disabled in this release of Snes9x. The code will
be changed soon to match the newer netplay protocols used by the Windows port
and released in a later version.

Super FX
========

The Super FX is a 10/21MHz RISC CPU developed by Argonaut Software used as a
game enhancer by several game tiles. Support is still a little buggy but most
games work very well, if a little slowly. Released SNES Super FX games included
Yoshi's Island (best single-player game on SNES, if you like platform games),
Doom, Winter Gold, Dirt Trax FX, StarFox, Stunt Race FX and Vortex. If you're
lucky, you might find a copy of the unreleased Starfox 2 image floating around,
but its sound code is corrupt and you'll need to disable sound CPU emulation to
play it.

Lots of Super FX ROM images available are in an odd, interleaved format that I
haven't worked out an easy way to auto-detect. If Snes9x detects that a 
Super FX game crashes (by executing a BRK instruction), it automatically 
assumes the ROM is in this odd format and de-mangles the ROM and tries to run
it again. If your ROM image isn't working, you could try using the -i2
command line option.

SA-1
====

The SA-1 is a fast, custom 65c816 8/16-bit processor, the same as inside the
SNES itself, but clocked at 10MHz compared to a maximum of 3.58MHz for the CPU
inside the SNES.

The SA-1 isn't just a CPU, it also contains some extra circuits developed by
Nintendo which includes some very fast RAM, a memory mapper, DMA and several
real-time timers.

Snes9X includes emulation of most features of the SA-1, enough to play all SA-1
games I've located so far, these include Mario RPG, Kirby Superstar and 
Paradius 3.

C4
==

The C4 is custom Capcom chip used only in the Megaman X2 and Megaman X3 games.
It can scale and rotate images, draw line-vector objects and do some simple
maths to rotate them.

Snes9x's C4 emulation is a direct copy of the ZSNES C4 emulation; Intel-based
ports even make use of ZSNES code. Without zsKnight's hard work, Snes9x would
not have C4 emulation. Many thanks go to him.

3Dfx Support
============

Included in this release of Snes9x is stage 1 Voodoo 3d graphics card support.
If you run gsnes9x and, it either has root permission or you install the 3dfx
kernel driver module, snes9x will use the 3dfx card to scale and interpolate
the SNES image to fill your whole monitor screen - the results look very nice.

Downloading textures to Voodoo cards isn't particularly fast, and snes9x has
to download each software rendered SNES image as a new texture every frame, so
using the 3dfx in this way isn't as fast as you might expect or as fast as I'd
hoped.

However, there is hope. Stage 2 support in future Snes9x versions will
dispense with the software rendering stage altogether, and get the 3dfx card
to render each frame directly, removing the need to download a large texture
each frame and speeding the whole process up; expect a large speed increase,
especially when SNES translucency effects are also being used in a game.

Stage 2 is now looking very unlikely that it will ever happen - my Voodoo 2
card is broken and my Voodoo 3 card causes my desktop machine to hang when
another graphics card is in the AGP slot, so the Voodoo card is unplugged,
gathering dust at the moment. Without access to a Voodoo card I can't
develop any Glide software.

Problems With ROMs
==================

If the emulator just displays a black screen for over 10 seconds, then one
of the following could be true:

1) Someone has edited the Nintendo ROM information area inside the ROM image
   and Snes9x can't work out what format ROM image is in. Try playing
   around with the ROM options: -i, -fl, -fh, -hd, -nhd.
2) The ROM image is corrupt. If you're loading from CD, I know it might
   sound silly, but is the CD dirty?
3) The original SNES ROM cartridge had additional hardware inside that is not
   emulated yet and might never be - e.g. Street Fighter Alpha 2 (S-DD1).
4) The game is Starfox 2 beta; the only available ROM image is correct and it
   downloads junk code onto the SNES CPU, crashing it. Disable sound emulation
   to get the ROM to work.

The following ROMs are known not to work with any version of Snes9x:
o All DSP-1 games except Mario Kart, e.g. Pilotwings, Ballz 3d, Topgear 3000
  (incomplete DSP-1 emulation)
o Street Fighter Alpha 2, Star Ocean (missing S-DD1 emulation)
o Exhaust Heat2 (custom co-processor)
o Metal Combat (OBC1)

Sound Problems
==============

No sound coming from any SNES game using Snes9x? Could be any or all of
these:

- Snes9x couldn't open the sound device (/dev/dsp) when it started (Snes9x
  should display an error message), a permissions problem, the device doesn't
  exist or some other process already has the sound device open.
- The kernel doesn't support your sound hardware (Linux barely supports the
  sound card in my new laptop, I'm stuck with 8-bit sound only at the moment).
- You haven't got the volume control on your speakers turned down, have you?

General sound problems:

- Sound samples keep repeating or don't switch off, especially ones
  that play lots of speech samples, try -envx (e.g. Mortal Kombat series) or
  -sy.
- Sound quality is poor on all games. You have a noisy sound card (usually 
  cheap cards) or one that Linux only supports at 8-bit; turning on 
  interpolated sound (-is), sound-sync (-sy) and/or increasing the playback
  rate (-r 1-7]) will help.

  Note that sound-sync does not work very well with the thread sound option
  enabled due to real-time inter-thread timing problems with mutex locking.
- Snes9x runs really slowly or locks up with sound enabled on all games. If 
  you have a Sound Blaster Live card, enable thread sound (-ts): the sound
  card's beta Linux driver is broken and keeps reporting it can accept more 
  sound data when in actual fact it cannot. Snes9x creates another thread to
  feed data to the sound card which doesn't lock up the SNES emulation when 
  it is blocked trying to write more data to the card.
- Sound in a few games sounds crackly. Try turning off sync-sound and/or 
  interpolated sound - both seem to have problems with a few games.

The following games have sound problems in all versions of Snes9x - they spool
sound data between two CPU in real-time as the sound is playing:

o Earth Worm Jim 2
o Primal Rage
o Madden 94, 95, 96, ...
o NHL 94, 95, ...
o Weaponlord
o Clay Fighter
o Clay Fighter 2

Converting ROM Images
=====================

If you have a ROM image in several pieces, simply rename them so their
filename extensions are numbered: e.g. game.1, game.2, etc. Then, when
loading the ROM image, just specify the name of the first part; the remaining
parts will be loaded automatically.

If they are already in the form sf32xxxa, sf32xxxb, etc., you don't even have
to rename them; just specify the name of the first part, as above.

Emulation speed
===============

Emulating an SNES is very compute intensive, with its two or three CPUs,
an 8 channel digital sound processor with real-time sound sample decompression
and stereo sound, two custom graphics processors, etc.

If you only have a 486 machine, you will need to stick to using only 8-bit
graphics and minimal or no sound:

With sound:
snes9x -ne -r 1 -mono <rom filename>

Without sound:
snes9x -ns <ROM filename>.

Disabling the joystick support will also help (-j).

For maximum speed, if you're using the X Window System port, make sure your
X server is set to depth 8 and transparency effects are not enabled, or your
X server is set to depth 15 or 16 if you want transparency effects.

If you want to use the TV mode (-y), switching to a full-screen display is
usually fastest with the X server set to depth 15 or 16.

Don't enable the scale option and don't resize the window on the X Windows
port.

Users with slower Pentium machines might want to turn off echo and digital
FIR filter effects, due to the number of multiply operations needed to
implement them. Use -ne option.

Got a big throbbing beast of a CPU under the cover of your computer? These
options will sort out the men from the boys:
snes9x -y -sc -r 7 -sy <ROM filename>

Credits
-------

- Jerremy Koot for all his hard work on current and previous versions of 
  Snes96, Snes97 and Snes9x.
- Ivar for the original Super FX C emulation, DSP1 emulation work and 
  information on both chips.
- zsKnight and _Demo_ for the Intel Super FX assembler code.
- zsKnight and _Demo_ for all the other ideas I've nicked off them; they've
  nicked lots of my ideas and information too!
- DiskDude's SNES Kart v1.6 document for the Game Genie(TM), Gold Finger and
  Pro Action Replay cheat system information.
- Lord ESNES for some nice chats and generally useful stuff.
- Lee Hyde ([e-mail]) for his quest for sound information and 
  the Windows 95 icon.
- Shawn Hargreaves for the rather good Allegro 3.0 DOS library.
- Robert Grubbs for the SideWinder information - although I didn't use his
  actual driver in the end.
- Steve Snake for his insights into SNES sound sample decompression.
- Vojtech Pavlik for the Linux joystick driver patches.
- Maciej Babinski for the basics of Linux's DGA X server extensions.
- Alexander Larsson for the GGI Linux port code.
- Harald Fielker for some sound interpolation code (not included in this 
  release due to problems).
- Takehiro TOMINAGA for many speed up suggestions and bug fixes.

Nintendo is a trademark.
Super NES, SuperScope and Super FX are a trademarks of Nintendo. 
Sun, Solaris and Sparc are all trademarks of Sun Microsystems, Inc.  
Game Genie is a trademark of Lewis Galoob Toys, Inc.
MS-DOS and Windows 95 are trademarks of Microsoft Corp.
Intel, Pentium and MMX are all trademarks of Intel Corp.
Sony is a trademark of Sony Corp.
UNIX is a registered trademark of X/Open.
Glide is a trademark of 3Dfx Interactive, inc.

------------------------------------------------------------------------------
Gary Henderson
[e-mail]