Sega Genesis Gamers 

Console & Archive Stats

Cd Design and Programming by Dr.X

 What I need to get Gens working ? 

Minimun Machine

- Pentium 166 (MMX is required for 2xSaI Kreed's engine)
- 16 Mb de Ram
- Video card 2 Mo (4Mo for triple buffer) with DirectDraw support and 15/16 bpp mode.
- Win9X / Win2000
- DirectX 7.0

Recommended Machine (if you want 60 FPS)

- Pentium II 300 Mhz
- A good video card like tnt ...
- 32 Mb Ram
- Win9X / Win2000
- DirectX 7.0

Use the normal render mode (in 'graphics' menu) to get the best performance.

Shortcuts :

Open Rom Ctrl + O
Close Rom Ctrl + C
Rom 1 (history) Ctrl + 1
Rom 2 (history) Ctrl + 2
Rom 3 (history) Ctrl + 3
Rom 4 (history) Ctrl + 4
Rom 5 (history) Ctrl + 5
Rom 6 (history) Ctrl + 6
Rom 7 (history) Ctrl + 7
Rom 8 (history) Ctrl + 8
Rom 9 (history) Ctrl + 9
Auto Frame-Skip F2
Frame-Skip - 1 F3
Frame-Skip + 1 F4
Save State F5
Previous state F6
Next State F7
Load State F8
Fast Blur F9
Show FPS F10
Previous Render Mode F11
Next Render Mode F12
Full-Screen / Window Mode Alt + Return
Screen shot Shift + S
Strech image Ctrl + S
VSync (full screen only) Ctrl + V
Hard Reset TAB
Pause ESC

Render Mode:

F11 320x240 640x480 640x480 640x480 640x480 640x480 640x480 F12
Normal Double Full Scanline 50% Scanline 25% Scanline Interpolated-Scanline 2xSaI


- when you use the fullscreen, the window-menu is replaced by a popup menu,
press the right mouse button to make it appears.
- gens has 2 renders mode, one in full-screen and an other in windowed mode.
This allow you to avoid to change the current rendering mode each time you're switching from or to fullscreen.
For instance, if you prefer "2xSAI render" in fullscreen and "double render" in windowed, just choose once "double render" in windowed then
go to fullscreen, change to 2xSai...
Now if you go back to windowed mode, the "double render" is chosen and when
you go back to fullscreen mode, "2xSAI render" is activated.
- "strech" feature isn't available for all scanlines renders & 2xSAI render when you are in fullscreen.


First, be sure you have the kailleraclient.dll file in your Gens directory (anyway, the emu doesn't start if isn't the case).
Well, go to 'file->Netplay' then the kaillera server selection dialog appear ...
Don't forget to specify a user name.
if you want to play on the NET, be sure that you're connected (^-^), if you want to play on local network, just specify the IP of the
kaillera server (you can download the server at
Choose the server where you want to play, then a other dialog appears and you can see others players connected to the server and theirs
status (idle, playing ...), also you can see the current created games, if you wish to play one of them (and the status is waiting) then
just 'join' the game ...
YOU HAVE TO HAVE THE EXACT SAME NAME OF THE ROM (so better to use goodgen to rename your roms).
But you can create a game by clicking on the 'Create new game' button, then a list of game should appear (it's the list of all the roms you
have in your last rom loaded directory).
Then you can wait for others players and start the game alone ;)
When you want to stop the game, YOU HAVE TO CLOSE THE ROM (Menu 'File->close rom' or Ctrl+C) then you can start an other netplay party.
If you want to exit Gens, you have to close all the kaillera dialog (the little before to avoid crashe ... a bug of kaillera), then you can close Gens.
Sorry for all these convenients, but Kaillera has be made for MAME first and Gens works in a complety different way ...
If you want more informations about how use Kaillera, check the homepage at

For others emulator authors who want to be compatible with Gens for NETPLAY, here's the format of the data
sent with kailleraModifyPlayValues function for one player (2 bytes of lenght) :

F E D C B A 9 8 7 6 5 4 3 2 1 0

1 1 1 1 M X Y Z S A B C U D L R
o t p o e i
d a w f g
e r n t h
t t

Value : 0 if the button is pressed and 1 in other case.


Q : I got the following message : "Error with Query Interface", how fix it ?
A : You just have to reinstall directX 7.0 (or above).

Q : I can't set my joypad because keys are automatically pressed (quickly), what's the problem ?
A : Reinstall your joypad in the window joystick/joypad panel then reinstall DirectX, if still not fixed ... no luck.

Q : 2xSAI doesn't work in fullsreen !
A : 2xSAI works perfectly in fullscreen, use F11/F12 to switch the current render mode.
Gens has a separate render mode for fullscreen and windowed mode.

Q : Game Genie doesn't work !!!
A : Download the Gens manual at which explain how use it.

Q : Where i can find roms ?
A : it's easy to find roms with search engine, don't forget that isn't legal to have roms
if you don't have the original game, i can't be responsible for your acts.

Q : How exiting Netplay ?
A : First, you have to close the rom (Ctrl+C) then close the Kaillera client windows.

Q : Netplay sometimes crashs ...
A : I know, Kaillera library has some bugs, Gens has others so ...

Q : Funny day isn't it ?
A : Intro Style=1 ...

Technical infos

* 68000 CPU :
Starscream 680x0 emulation library by Neill Corlett ( modified for Gens.
* VDP :
- DMA transfers (all modes and timing respected)
- Scroll A plane with vertical scrolling (overall, 2 cells) and
horizontal scrolling (overall, cell, dot)
- Scroll B plane with vertical scrolling (overall, 2 cells) and
horizontal scrolling (overall, cell, dot)
- Window plane
- Sprite plane
- Vertical Interrupt
- Horizontal Interrupt
- All raster effects
- Highlight/Shadow effects
- Interlaced mode
- Sprite collision & sprite overflow flags
* IO ports :
- controller 1 and controller 2 with 3/6 boutons pad.
- partial 4 players adaptater (multipad).
* Z80 CPU emulation :
RAZE Z80 core by Richard Mitton ( modified for Gens.
* YM2612 chip emulation by Tatsuyuki Satoh
* PSG 76489 emulation
* SRAM supported (except custom SRAM chip).
* Frame Skip (Auto, 0, 1, 2, 3, 4)
* Save/Load State.
* Window / Fullscreen Render (scanline and 2xSaI support).
* Netplay (Kaillera).

What is lacking :

* SVP chip support
* Menacer support
* Custom SRAM chip support

Compatibility :

Red5 from the Genesis Project has tested 0-J and S-Z games with Gens v0.99
92% of games work perfectly + 4% are playables with some glitches.
Then 96% of games are playables :)