DS2x86 Alpha 0.01 release! - Dos Emulator for DS & Supercard DSTwo Flash Cart

December 28th, 2010, 22:59 Posted By: wraggster

Pate has posted the first release of his Dos Emulator for DS & Supercard DSTwo Flash Cart

Well, here it finally is, the first alpha version of DS2x86! Please note that this is a very early alpha, and it has a lot of bugs and missing features. You should consider this just a test bench for my DSx86 port to the built-in 360MHz MIPS processor of the SuperCard DSTwo flash cart. But, since a few games seem to be somewhat playable already, and as I sort of promised an alpha version by the end of the year, here it is!

Installation
If you already have a working DSx86 installation on your flash cart, all you need to do is to copy the "DS2x86.plg", "DS2x86.bmp" and "DS2x86.ini" files into the "_dstwoplug" directory of your SD card. DS2x86 can use the same DSx86.ini file that you have used in the original DSx86. You can also use a separate DS2x86.ini if you wish to have different settings for DS2x86 and DSx86. NOTE! Do not confuse the two DS2x86.ini files! The one included in the zip file is the one required by the DSTwo plugin system, the one in the /data/dsx86 directory (and created by you) is the one used by the DS2x86 itself for game-specific configuration.

If you do not yet have the original DSx86 on your SD card, follow the instructions on my download page (or at DSx86 Compatibility Wiki). It is recommended you familiarize yourself with the original DSx86 first, before testing DS2x86. Or, you might want to wait for a more stable version of DS2x86 before installing it.

Limitations compared to DSx86

Obviously, DS2x86 only runs on the SuperCard DSTwo flash cart, as it uses the MIPS processor of that cart, not the ARM processor of the Nintendo DS/DSL/DSi itself.
Not all 80186 opcodes have been ported over yet, so some games that do run in the original DSx86 will not run in this alpha version yet.
Audio support is very poor, only SoundBlaster 8-bit DMA audio is supported, all other audio output is still missing.
ScreenMode "Jitter" was removed. If the configuration ini file uses Jitter, it will be replaced by Scale.
ScreenMode "Scale" only works in MCGA and EGA modes, not in Text, CGA or Mode-X graphics modes.
Screen refresh rate is locked to 15fps. I just recently noticed that there are various problems with both keyboard reading and screen refreshing when attempting to use higher refresh rates. I hope to fix these issues and allow faster screen refresh rates in the future.
All high-resolution EGA, VGA and Mode-X graphics mode support is still missing. You will either get a black screen or the previous mode graphics sticking on the screen when going to high-resolution graphics mode.
Mouse support is mostly missing, and what little support there is, is still completely untested.
No blinking cursor on the DOS prompt.

Enhancements compared to DSx86

Some 386-specific opcodes are supported. The support is blotchy at best, so it is more than likely you will run into an unsupported opcode when testing a 386-specific game.
The x86 Parity and Auxiliary Carry flags are properly supported (it was architecturally impossible to support these properly in the original DSx86).
The screen scaling uses proper linear interpolation, which produces better image quality than the hardware scaling used in the original DSx86.
Speed! You can select the CPU speed between 60MHz and 396MHz, with the emulation speed ranging from 10MHz 80286 machine to 40MHz 80386 machine. Note that speeds lower than 240MHz might have stability issues, as the DSTwo interface can not keep up with the amount of data needing transfer.

Issues you might run into

The keyboard reading has some synchronization issues when using non-default CPU speeds. If you notice key presses/releases to not get recognized, try changing the CPU speed (by clicking on the touchpad MHz indicator).
If DS2x86 drops into the debugger, it has written a debug crash log into the dsx86dbg.log file. Please send this file to me so that I can add support to this opcode in future versions!
You might also get a "Blue Screen Of Death" on the lower screen, stating that a certain exception has occurred. This does not get written to the log file (as the system status is unstable at that point), so if you can write the numbers down and email them to me, together with information about what you were doing, that would help me in improving DS2x86.

Thanks for your interest in DS2x86! Have fun testing it, and again, please remember this is a very early alpha version! Be surprised if something actually works, not if it fails! :-)

http://dsx86.patrickaalto.com/DSblog.html

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