DX Sega in a Gamepad

[socram8888]

I bought the DealExtreme Sega Genesis in a Gamepad. It has got a SD card slot to load ROMs and homebrew (this: www.dealextreme.com/details.dx/sku.30606 )

Also, seems that this gamepad has perfect Sega Genesis emulation: even 3D games works (incluiding Hardwired!). I made some months ago a Homebrew and I tested in it: www.youtube.com/watch?v=IwYjuvaOFEY

DealExtreme released a new firmware. With a hex editor, I found the menu at offset 0x20000. But it's a SEGA GENESIS ROM, NOT A SPECIAL PROGRAM.

Then, seems that the SD is controlled by software, and I was wondering about to hack it to use with BasiEgaXorz homebrew for reading and writting data to it. Is it possible? A OS would be extremely nice!

In www.dealextreme.com/forums/Forums.dx/Forum.0~threadid.484444 there are more info related to offsets (search for socram8888 posts)

Thank you

PS: Anyone has got a 68k decompiler? I can't find one!

[Mairtrus]

I saw this some time ago, but I was wondering if it really works as a real Genny. Seems that now I have no reason to don't get one of those things.
For intensive tests, try some of the tech demos on Tiido's webpage. All of them are really awesome.

And about your other question, try to get SEGADASM. For me, is the best sega genesis disassembler.

[Tom Maneiro]

What class of weird emulator allows direct hardware access? On the other side, SD is not a really complex protocol...

[oompa loompa]

i just heard about this too, the e-time came out sometime last year so it's pretty new . it's one of those sega genesis system-on-a-chip thing chipsets that is in pretty much all the modern sega genesis clones. i made a pretty comprehensive guide about the sega radica, which is a chip on board sega genesis also. the only thing that is not perfect about these clones is the ym2612 logic

i dunno, i'm assuming that there is a big chunk of NOR flash on this that holds the game that is playing. SD cards are way too slow for random accesses. is there any loading time when loading a game from the sd card into its flash?

there's also a portable (gameboy like) version of this called the mega drive gopher. i was interested in getting the portable version, but then i saw the Dingoo A320 for $90, which emulates the older console system, and has a MIPS core. it also has tv-out as well

i think the best way to reverse engineer a console rom is to actually load the rom into an emulator which has tracing support. there's a gens mod at doc.kodewerx.org which does this. but yea, if you can't get the rom dumped, or if it gets stuck in the emulator, then you got to do a lot of disassembly. SEGADASM is the best like mairtus said

[socram8888]

I dumped the ROM: DealExtreme released a new firmware, and I saw that in 0x20000 is the Sega Genesis game selection menu (in 68k, even with the Sega Genesis header and the TMSS!)

The ROM is copyed first to a internal 64 Mb parallel NOR FLASH (8MB, with 16 bit data interface). Only the first execution is copyed, and two games can be at the same time in the NOR.

Using the Gens Tracer version, and with hook_log.txt configured to take every write, I got the next hook.txt:

[00:0242] VDP REG W08 = 04 [00]
[00:0242] VDP REG W08 = 04 [00]
[00:0242] VDP REG W08 = 04 [00]
[00:0248] VRAM DMA from 000000 to 0000 [FFFE]
- SRC_H = [00:0240] ~~ LEN_H = [00:0240]

[00:0248] VRAM DMA from 000000 to 0000 [FFFE]
- SRC_H = [00:0240] ~~ LEN_H = [00:0240]

[00:0248] VRAM DMA from 000000 to 0000 [FFFE]
- SRC_H = [00:0240] ~~ LEN_H = [00:0240]

[00:070E] VDP REG W08 = 14 [00]
[00:070E] VDP REG W08 = 14 [00]
[00:070E] VDP REG W08 = 14 [00]

Just VRAM writtings I'll try again with a different hook_log.txt

See you soon

[oompa loompa]

Are you sure you have the Gens Tracer tool working properly? I would probably think that the cart locks up because it doesn't see its hardware

How long does it take to load a 4mbyte game (say sonic 3d blast) from the SD card into the NOR?

[socram8888]

I don't have one now (I had one but the firmware got corrupted), but I can remember is less than 1 minute.

I saw in the code that the SD and filesystem is controlled by the CPU in native mode (that's it: the SD is not controlled with the emulated menu). But maybe a raw access to the SD is available...

[Deleted]

I bought one and the load time is annoying. Also, the colors are washed out on most TVs I've tried it on. Still, the price and the fact it runs off of batteries is N I C E

My NOMAD is getting lonelier for sure!