A quick tutorial how to install PS1 EMULATOR.
Your phone does not have to be rooted!
Checked and working with Galaxy ACE 2 (it also works with other phone models. As far as I know starting from Eclair 2.1)...
1) Download emulator from ---> here
2) Connect your phone and extract "Emulator.rar" to your external SD or phone memory
3) Disconnect your phone from computer, go to settings ---> applications and allow to install non-market applications.
4) Go to my meniu and select icon MY FILES. Then find the place where you have extracted "Emulator.rar" press on "psx4droid.apk.apk" and confirm installation.
5) Emulator is installed. Run it! Then program will ask for a BIOS file.. It was included with emulator. So, go back to that location where you have extracted "Emulator.rar" and select "SCPH1001" file.
6) Done! Your emulator is ready for use!
7) You can download games ---> here
8) P.S. Most of the games are zipped. Extract them to your external SD card to save space. Currenly I've tried Yu-Gi-Oh and one of the Dragon Ball series games. Working like a charm! Not lag at all! If you have any further questions - contact with me
Your phone does not have to be rooted!

Checked and working with Galaxy ACE 2 (it also works with other phone models. As far as I know starting from Eclair 2.1)...
1) Download emulator from ---> here
2) Connect your phone and extract "Emulator.rar" to your external SD or phone memory
3) Disconnect your phone from computer, go to settings ---> applications and allow to install non-market applications.
4) Go to my meniu and select icon MY FILES. Then find the place where you have extracted "Emulator.rar" press on "psx4droid.apk.apk" and confirm installation.
5) Emulator is installed. Run it! Then program will ask for a BIOS file.. It was included with emulator. So, go back to that location where you have extracted "Emulator.rar" and select "SCPH1001" file.
6) Done! Your emulator is ready for use!
7) You can download games ---> here
8) P.S. Most of the games are zipped. Extract them to your external SD card to save space. Currenly I've tried Yu-Gi-Oh and one of the Dragon Ball series games. Working like a charm! Not lag at all! If you have any further questions - contact with me

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HOW TO IMPROVE PERFORMANCE
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HOW TO IMPROVE PERFORMANCE
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Go to program settings and ---> !!DISABLE AUTO FRAME SKIP!! (uncheck)
Official WebSite: http://www.zodttd.com/
Official WebSite: http://www.zodttd.com/