dgen.txt

DGen源码最后版本

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     it's all just a little bit of history repeating...

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DGen is a Genesis/Megadrive emulator, which currently
runs under for Windows 95/98/NT/2000 using DirectX.

(The name is spelt "Capital D, Captial G, small e, small n",
and pronounced "Dee Jen".)

At this point I'll slip in the old standard disclaimer:
  I do not accept responsibility for any effects, adverse or otherwise,
  that this code may have on you, your computer, your sanity, your dog, 
  and anything else that you can think of. Use it at your own risk.

----------------------------------------------
V1.17

+ Added in Joe's new graphics engine with fixes to the Window/Scroll plane
  interaction (thanks to Steve Snake for the information).
  Herzog Zwei's 2-player mode is now okay, and I imagine you will
  see improvements in other games as well.
  
V1.16

+ Game Genie codes and general ROM patching, thanks to Joe Groff (Linux port).
  Load the ROM, select Genie Codes from the file menu,
  type in your codes (separated by spaces)
  and hit Patch, then Fix Checksum and then Close.

  Windows comes in handy here because I would find it much easier
  to cut and paste Game Genie codes (by clicking on the text
  box and pressing Control-V).

  The codes will take effect until you close the game, but if you
  want to reset them without closing the game you can try the new
  'Reload' option, which reloads the ROM from disk, but doesn't reset
  the Megadrive.

  A lot of games won't reset properly (displaying only a RED SCREEN)
  with an incorrect ROM checksum (caused by using a Genie code),
  but the 'Fix Checksum' option should solve this.

V1.15
+ Raster Effects!
  Offset By Line!
  These are both working thanks to the new line-based graphics engine.
  (DGen has been noticably missing a line-based engine).
  The guys doing the MacOS version (more specifically John Stiles
  I think) have provided this engine, and it's very good!
  DGen now has two working graphics engines and one work in progress.
  (0: MacOS line-based
   1: My tile-based and
   2: my line-based which doesn't work yet.)
  You can switch between them from Graphics/Engine in the menu.
  I think there may even be a fourth engine in the pipeline from
  the Linux side!

+ Thanks to the above, Sonic1 level 4 and Toe-jam are virtually perfect now.
+ After burner too.
+ Road Rash nearly works perfectly BUT sadly...
- flickers REALLY badly when you go over a crest.
  (So don't play it if you've got epilepsy or something!)
  This is a *real* shame.
- and Super Monaco is a mess...

+ New DirectDraw code. Let me know how it goes.

V1.14

+ SRAM support thanks to both the MacOS team and Joe Groff who
  have both been working on this. Let me know if you find
  games with Save RAM which still don't work.
  By default DGen automatically saves and loads SRAM from (romname).srm
  (In case you are not familiar with SRAM, a.k.a Battery Backup,
   this is save memory, typically for RPGs, which lets you save your
   game while the machine is off.)

+ More support for people without sound cards, or people with dodgy
  DirectSound (e.g. Windows NT) who want to turn it off. In particular
  I fixed the crash when you hit the menus. You have the option of
  turning off sound: DGen will then speed throttle without
  using the DirectSound loop. This is very useful if you are using
  another program with digital sound (e.g. WinAmp).

I have another Windows code framework with a text console,
but it is not ready for public release yet, so this version uses the
'old' interface.

+ I think I may have fixed the redefining keys trouble that some people
  reported. The cause turned out to be unconnected controllers producing
  phantom input, confusing the redefining algorithm. This also caused
  a much more serious effect: a 2 or 3x performance slowdown.
  After tracking down the problem the solution was simple: check at the
  start for unconnected controllers and ignore them.
  Report back to me on how V1.14 works for you.

+ StarScream, the fast 68000 emulator, has been publicly released
  by Neill Corlett, which is great. The current version is 0.26a, so DGen's
  code now uses that version.

+ MJazz option - puts 2 more FM chips in the Megadrive for
  a sort of 22 channel sound boost. Can sound good. Slows things down a lot.


V1.13
- Lots of things broke!

V1.12
What's new?
+ Graphics speedup (10-15%)

V1.11
What's new?
+ Zipped ROM Support
+ More accurate VDP registers
+ FM music will not reset after toggling fullscreen
  or changing settings (like it used to).

V1.10
What's new?
+ Medley mode: let's you automatically play sound tests in sequence.
* did anyone have a crash under NT? is it fixed?

(V1.09 was the source code)

V1.08
What's new?
+ PSG sound! This will fill in all the remaining sounds and music
  bits you may have been missing.

V1.07
What's new?
+ More accurate FM timers.
  The amount of games with music and sound has gone up from about
  50 to 99%!

+ Also because of the cycle-accurate cpu emulators
  the music is unlikely to slow down or speed up unpredictably.
  (e.g. in Thunderforce III under Genecyst, the music slows down
  as you fire, whereas this is fixed under DGen.)

* Made split_screen off the default. Turn it on for Sonic2/3

V1.06
What's new? (A shorter question would be, what ISN'T new!)

+ Added SIX-BUTTON support. Not sure how it compares to Genecyst
  so let me know.
+ You can redefine your keys/buttons now (in the Input menu)
+ Added the Musashi 68000 C emu by Karl Stenerud, which is slower but
  more accurate. You can pick between the StarScream
  (very fast and the default) and Musashi.
  Mushashi fixes playability problems with Rolling Thunder 2 (sprite reverse),
  Eternal Champions (jump), and Columns (ridiculous scores).
+ Many, many, many options now in the menu
+ Version select / Auto-version
+ Sonic 1 level 4 now seems okay
+ Slightly faster CTV (15/16-bit)
+ Probably added lots of other stuff which I can't remember!

By the way, although Steve Snake gave me some code for DirectInput,
if it fails for any reason it's most likely *my* fault
since I've changed it quite a lot! Let me know if your joystick
doesn't work (and you HAVE set it up correctly in Window's control
panel, and redefined keys to it in DGen).

* Let me know if DGen works with fancy joypads, or multiple
  joypads (I only have one simple one).
* Also let me know if that DIrectInput SNES Pad thing works.

- (I recommend you don't use fullscreen mode to change settings:
   Alt-Tab switch back to a Window, make the changes, and then
   Alt-Tab switch to full screen.)
  (Also, I recommend you Alt-Tab switch back to a window before you exit)

V1.05

+ Joystick support.
  DirectInput support thanks to Steve Snake!

--------------------------------------------------------------
NOTE - In the DOS version, press F1,F2 or F3 to strech the screen,
F1 being the fastest. The DOS version doesn't have sound.
Type dgen -help for more info on how to work it.
The rest of this file refers to the Windows version.

V1.01: Added DGEN.INI file.
--------------------------------------------------------------


Automatically created configuration file is DGEN.INI,
which is usually create in the same directory
as where you run it (but Windows can be a bit unpredictable so you
may have to hunt around for it!).

Q: How fast is it?
A: Roughly speaking it compares like this:

Slow                                         Fast/
/Jerky graphics                              Smooth Graphics
  <------------------------------------------>
                DGEN            Genecyst
             Megasis            KGen

but hey - you can compare for yourself!
Certainly works well on my P2-333.
Runs terrible on a P1-150! (try increasing snd_segs)
If you have a Pentium-I or below then I advise you to use KGen or Genecyst.
If you have a Pentium-II 333 you should have no trouble.

Q: Why use it rather than Genecyst and KGen?
A1: It has interlace mode support
A2: DOS programs sometimes have trouble with newer graphics cards and
   sound cards. (It's happened to me a couple of times.)

Q: What's the compatibilty like?
A: Not bad, but sound is missing from a lot of games sadly.

---------------------------------------------------------------

.gsx files are a bit like gs0-gs9 save states, so you may be able
to swap save states between emulators. Anyone got the actual
specs for Genecyst or KGen save states?


*****************************************************************

READ BEFORE E-MAILLING DAVE:

- No ROM requests!

That's it really...

-----------------------

Homepage for DGen and DTMNT is:
  http://www.dtmnt.com/

Dave's e-mail
[e-mail]

Technical Bits
--------------

+ Scroll A/B Low/High and Window
+ Per screen offset supported
+ Per tile offset supported
+ Per line offset supported
+ 16-bit Stereo Sound
+ 68000 and Z80 supported
+ YM2612 supported (e.g. Music)
+ Z80 DAC supported (e.g. Drums and speech)
+ PSG chip supported (e.g. extra music/sound bits)
+ Raster effects supported (e.g. Toe-jam, sonic3)
+ H-ints supported a bit (e.g. Moonwalker)
+ Save RAM supported

Credits
-------

* Neill Corlett for the very fast StarScream 68000 emulator
* Neil Bradley for the very fast Multi-Z80 emulator
* Tatsuyuki Satoh for the YM2612 emulation
* Me for putting it all together
* Me for Genesis and VDP emulation
* Me for the C++/assembler graphics rendering.
* Microsoft's *good* programmers who seem to have designed DirectDraw/Input/
  Sound but not the other lardy Microsoft products, which usually have a date
  later than 1996 in the title.
* Steve Snake (of KGen fame) for the DirectInput code
* Karl Stenerud for the accurate Musashi 68000 emu
* Alex Townsend for the Zipped ROM support
* Richard Bannister and a countless other Mac programmers
  for the MacOS version and loads of code.
* In particular John Stiles for the line-based renderer
* Joe Groff for the Linux version and loads more code!
* Flavio Morsoletto for a huge amount of technical Megadrive info.
--------------