Rewriting a VT03 Famiclone's Flash Memory Chip

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dj505
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Rewriting a VT03 Famiclone's Flash Memory Chip

Post by dj505 » Sun Feb 25, 2018 7:38 pm

Edit: This does not seem to be a VT03 after all; it's starting to seem like part of the VTxxx series

Hey! I've never done any NES development before, but I have done a fair amount of hardware modding, and I have a quick question.
I got this Famiclone 200-in-1 arcade machine thing from WalMart:

Image

I meant to take it apart and put a Raspberry Pi in it, but I got a bit sidetracked by the hardware. A ton of research without prior famiclone knowledge and some hardmodding later, it turns out this thing is a VT03-based famiclone. The 200-in-1 multicart ROM is stored in a little Winbond W25Q64FV flash memory chip, which I've managed to dump with the help of a Raspberry Pi and FlashROM. The resulting image does indeed run properly in a VT03 emulator.

My next test (and here's where my question comes in) was to write a different ROM to it. FlashROM won't write anything that's not exactly 8388608 bytes, so I opted for a dump of the same 200-in-1 multicart that was dumped from a different console; this time a Plug-n-Play, instead of something with a built in screen. I was able to successfully flash the ROM to the famiclone's memory, and it did indeed boot - but the screen didn't even turn on. Audio did work, however. This makes me think that the original multicart ROM that it came with actually initialized the screen as part of the startup process, but the image from the other clone didn't need to do this as it outputted to a TV like a typical famiclone instead. Mainly, what I'm curious about is this:

Would it somehow be possible to write a normal NES game (or more likely another VT03 game) to this thing's memory - along with whatever initializes the screen added onto it - and play that on the unit?

EDIT: Not sure what the rules here on are sharing dumps, but here's a dump of the Famiclone's flash memory: http://www.mediafire.com/file/bagaeliel ... 201%29.rar
Last edited by dj505 on Wed Feb 28, 2018 10:49 am, edited 2 times in total.

guyman70718
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Re: Rewriting a VT03 Famiclone's Flash Memory Chip

Post by guyman70718 » Sun Feb 25, 2018 8:20 pm

Thats cool, wouldnt have ever tried that myself, I usually just laugh when I see things like that. I always thought they were emulators not real hardware. If file size is an issue, maybe try expanding the image with something like gparted?

lidnariq
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Re: Rewriting a VT03 Famiclone's Flash Memory Chip

Post by lidnariq » Sun Feb 25, 2018 8:30 pm

Have you compared the original flash image to the one you replaced it with?

VRTech's website has been partially restored, and you can again get information about their chips from them, but the original VT03 doesn't support anything but composite output.

The VT18 appears to support an analog RGB TFT LCD; it has a new register at $4120 that ... somehow controls the resolution of the output LCD but I can't figure out how.

Their documentation on their VT1682 also claim support for some kind of analog LCD also, but specifics are even more lacking.

(edit) ... looks like it's specifically the VT1682 that includes a boot ROM on die and can operate out of serial flash instead of needing an external parallel memory.

I have to admit, entirely unrelatedly, that I'm unreasonably excited by the idea of being able to go buy one of these silly famiclones, even if it means I'd have to desolder the flash to get anything useful out of it.
Last edited by lidnariq on Sun Feb 25, 2018 8:44 pm, edited 1 time in total.

dj505
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Re: Rewriting a VT03 Famiclone's Flash Memory Chip

Post by dj505 » Sun Feb 25, 2018 8:43 pm

lidnariq wrote:Have you compared the original flash image to the one you replaced it with?

VRTech's website has been partially restored, and you can again get information about their chips from them, but the original VT03 doesn't support anything but composite output.

The VT18 appears to support an analog RGB TFT LCD; it has a new register at $4120 that ... somehow controls the resolution of the output LCD but I can't figure out how.

Their documentation on their VT168 and VT1682 also claim support for some kind of analog LCD also, but specifics are even more lacking.

I have to admit, entirely unrelatedly, that I'm unreasonably excited by the idea of being able to go buy one of these silly famiclones, even if it means I'd have to desolder the flash to get anything useful out of it.
Hmmm, it must not be a VT03 in that case... This thing does indeed have a TFT LCD built in, but I couldn't find out anything about it online and there are no part numbers on it to go by (at least none that were useful).

I'm gonna try and few VT18 ROMs or something on it and see if those work by any chance. Thanks!

EDIT: So I still haven't had anything work yet, unfortunately. Still can't pin down what chip this uses.

NewRisingSun
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Re: Rewriting a VT03 Famiclone's Flash Memory Chip

Post by NewRisingSun » Tue Feb 27, 2018 11:07 am

That ROM image is almost identical to "200 in 1 Thumbs Up Retro TV Games" which davidstech posted at PGC. Even the game list is identical, only the blue background color in the menu is a different blue tone. I could imagine that they also differ in the display initialization code.

Also, none of the games actually use VT03 features, only VT02 bankswitching.

lidnariq
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Re: Rewriting a VT03 Famiclone's Flash Memory Chip

Post by lidnariq » Tue Feb 27, 2018 10:15 pm

Hm, this dump writes to a lot of registers in ranges that aren't mentioned by any of the documentation I've found.

E.g. the ten bytes $40, $A0, $00, $78, $FF, $69, $0A, $6B, $26, and $00 to addresses $2040 through $2049,and then $07 to $2055...

NewRisingSun
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Re: Rewriting a VT03 Famiclone's Flash Memory Chip

Post by NewRisingSun » Wed Feb 28, 2018 9:30 am

And tons of writes to 412D-43xx, which are also not defined for VT02-VT18. And all those writes are not in the 200-in-1 Retro TV Game ROM that I mentioned.

The write pattern in this ROM on the other hand matches that of the SY-889 handheld, which also has no marking on it but is assumed to be a VT36x.

dj505
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Re: Rewriting a VT03 Famiclone's Flash Memory Chip

Post by dj505 » Wed Feb 28, 2018 10:54 am

NewRisingSun wrote:And tons of writes to 412D-43xx, which are also not defined for VT02-VT18. And all those writes are not in the 200-in-1 Retro TV Game ROM that I mentioned.

The write pattern in this ROM on the other hand matches that of the SY-889 handheld, which also has no marking on it but is assumed to be a VT36x.
I tried that SY-889 dump the other day, it did in fact run (I could hear the menu music just fine) but the screen remained turned off. Although this does make it seem much more likely that it could be part of the VT36x family.

Edit: Neither the SY-889 or SY-888b dumps do anything that turns on the screen, but both do run.

timschuerewegen
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Re: Rewriting a VT03 Famiclone's Flash Memory Chip

Post by timschuerewegen » Wed Dec 04, 2019 10:51 am

dj505 wrote:
Wed Feb 28, 2018 10:54 am
I tried that SY-889 dump the other day, it did in fact run (I could hear the menu music just fine) but the screen remained turned off. Although this does make it seem much more likely that it could be part of the VT36x family.

Edit: Neither the SY-889 or SY-888b dumps do anything that turns on the screen, but both do run.
I am working on my own "NesMaker" software (the one from VRT is for older chipsets) to make new xxx-in-1 roms for VTxxx-based devices. I just added support (it works on NintendulatorNRS) for your "DreamGear My Arcade Retro Machine 200-in-1" device. If you would like to test the 61-in-1 rom I made, send me a PM.

timschuerewegen
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Re: Rewriting a VT03 Famiclone's Flash Memory Chip

Post by timschuerewegen » Fri Dec 06, 2019 1:43 pm

Here is my "NES Maker" software. Enjoy :)

NES Maker - 1.0.0

lidnariq
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Re: Rewriting a VT03 Famiclone's Flash Memory Chip

Post by lidnariq » Fri Dec 06, 2019 1:46 pm

Would you be willing to describe the restrictions on what the program can work with? All I see is an interface to choose one of 4 VRT machines, and and the ability to add ROMs to it, before it generates an image to be flashed to the SPI flash.

timschuerewegen
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Re: Rewriting a VT03 Famiclone's Flash Memory Chip

Post by timschuerewegen » Fri Dec 06, 2019 2:09 pm

lidnariq wrote:
Fri Dec 06, 2019 1:46 pm
Would you be willing to describe the restrictions on what the program can work with? All I see is an interface to choose one of 4 VRT machines, and and the ability to add ROMs to it, before it generates an image to be flashed to the SPI flash.
You can use NintendulatorNRS and the "Test" button to test the generated ROM. The only mappers that seem to work on the currently supported machines are 0 and 4.

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