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Messages - davidstech

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76
Famicom/NES dumps / 300-in-1 SY-889 Handheld Dump (VTxx)
« on: January 13, 2018, 08:52:47 AM »
Interesting, yes comparing them I think you're correct. In that case, it does remain a mystery what chip is inside this handheld - maybe someone really is cloning the VRT chips these days...

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Famicom/NES dumps / 300-in-1 SY-889 Handheld Dump (VTxx)
« on: January 13, 2018, 08:43:01 AM »
No worries, better to release it once the problem's solved.

Music sounds VTxx like to me, not sure what you think?
http://davidstech.net/games/multis/Adventure%20Island%20Intro%20-%20SY889.mp3

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Famicom/NES dumps / 300-in-1 SY-889 Handheld Dump (VTxx)
« on: January 13, 2018, 08:20:24 AM »
Awesome, I look forward to playing with it in Nintendulator :)

Game 41 does indeed glitch on the hardware.

I think the manufacturer of this handheld is Dongguan Changping Shengyuan Electronic Factory (东莞市常平胜源电子厂, aka "SY"), but the ROM was not built by them as many of the ROMs used were the "touchgameplayer" hacks.

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Famicom/NES dumps / 300-in-1 SY-889 Handheld Dump (VTxx)
« on: January 13, 2018, 07:20:21 AM »
Actually all those screenshots look correct, give or take LCD colours being slightly off. The only difference is that the menus on the handheld are cut off so you don't see the bit at the bottom. I've attached pictures taken from the hardware to compare.



Posted Image
Posted Image

Looking at strings in the ROM, towards the end there is "WISE@DJJUNGLE.CO" at 0x7FE4F3, which does suggest that VRT's tools were used at some point to build the ROM. Also very near the end there's a credit at 0x7FED23 "Program : Zhang Yuan Shen".

Attachments:

80
Other dumps / Mystery Dump: Unknown 1.8" Handheld
« on: January 13, 2018, 05:31:23 AM »
I have a feeling there are two platforms going on, which are confusing things. There is this platform, which is probably some random microcontroller, and there is the NES based platform that I have also now dumped (the 300 in 1) which use some kind of new NOAC with similarities to the VTxx architecture.

As far as I can tell there is nothing in common between these platforms except a low resolution screen - and a broadly similar CPU architecture, although the non-NES based ones use a 65C02 or similar enhanced variant whereas the NES ones use a plain 6502.

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Famicom/NES dumps / 300-in-1 SY-889 Handheld Dump (VTxx)
« on: January 12, 2018, 06:34:06 PM »
Interesting, thanks for taking the time to look at this. I'll investigate the the audio once it's put back together.

 Unfortunately I fear the exact chipset will remain a mystery maybe it's the "new" VT32 announced on VRT's website. Either way, do you it's worth adding a NES 2.0 header of some sorts to the ROM if you're thinking about adding support in your Nintendulator?
Wellminds have a list of platforms that they develop for here. Although I don't know if they were involved in this console, some of the ROMs are touchgameplayer ones that I think also feature on their consoles.

http://info.lcd88.com/201506/26-89861261844.shtml

The only candidate on the list for this console would be the VT32, but I'm not sure if that means much.

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Famicom/NES dumps / 300-in-1 SY-889 Handheld Dump (VTxx)
« on: January 12, 2018, 05:53:19 PM »
I need to put it back together and solder back the ROM to get pictures which will probably be tomorrow as I want to double check the dump first.

I'm not surprised about odd memory behaviour, the fact it uses an SQI flash means the memory interface must be new compared to earlier VTxx devices. I suspect this is a fairly recent and totally new VTxx platform, or maybe not even made by VRT at all but simply with a degree of compatibility.

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Famicom/NES dumps / 300-in-1 SY-889 Handheld Dump (VTxx)
« on: January 12, 2018, 10:55:07 AM »
This is a dump of one of the new low-res handhelds that are NES-based. I'm not sure if there's anything that interesting in this, but it was an easy dump so why not? This is definitely using one of the newer VTxx chipsets as it runs of SQI flash rather than parallel ROM/flash that earlier VTxx chips use. It runs in EmuVT using the VT09 settings, but with some graphical corruption.

http://davidstech.net/games/multis/300-in-1%20NES-based%20handheld%20(SY-889,%20W25Q64%20serial%20flash).7z

Attachments:

84
Other Pirates / Demystifying the 1.8in Handhelds
« on: December 21, 2017, 06:22:36 PM »
A bit more info, if anyone is curious.

With regards to these devices and the disassembly of their ROMs:

There seems to be RAM low down in memory,  seemingly around $0000..$0fff. Some code executes out of this.

Some frequently called and jumped to code is located around $6000..$6xxx. This is most likely an internal ROM in the processor. When functions here are called it seems data is passed by writing into consecutive memory locations starting at either $0100 or $0080.

There seems to be some kind of IO ports at $8000 and $c000. It looks like $8000 is for an address/command and $c000 for data. Maybe this is display related.

On a separate note, I also have some higher resolution also unknown devices. One of the higher resolution consoles I have with a similar set of games to the low res ones (the PCP station 8728 with "Bluetooth") seems to be based on the same hardware internally, and hence has framerate issues. The other with TV-out and a different set of games (the CY-699A, similar to the 828 taizou looked at IIRC) has totally different hardware inside with parallel flash and some kind of encryption/authentication chip. It does have 168 on the PCB so maybe even VT168. I haven't tried dumping the ROMs of either of these yet.

85
Famicom/NES / Work in Progress: new VT168 emulator
« on: December 21, 2017, 05:24:11 PM »
It turns out the reason that the racing games had graphical problems is that they were changing the PPU setup and tile map mid frame, which I hadn't anticipated in my code as I underestimated Waixing...

A new binary release with this fixed will come soon, just need to sort out a couple of other issues too.

Screenshots of some of the games are on the VTxxx page on BGW.

86
Famicom/NES / Work in Progress: new VT168 emulator
« on: December 20, 2017, 04:11:14 PM »
Y2K05
Dec 20 2017, 04:08:10 PM
Do you think emulation on a handheld like Android or Nintendo 3DS is more likely? Just wondering. It would be cool if it were on 3DS or Android since people still use those handhelds. Not just VTxxx but the VT03 and VT09 stuff too. I've been enjoying VT02 games on VirtuaNES on 3DS, and NESemu on my GPD XD.

Just wondering is all.[/quote]Android is the most likely, if I add this to MAME or make it into a retroarch core. Not sure about the VT03 or VT09 stuff, that would be best done by modifying an existing NES emulator for Android.

87
Famicom/NES / Work in Progress: new VT168 emulator
« on: December 20, 2017, 04:04:27 PM »
From a technical point of view it might work, anything that can emulate a SNES could emulate a VT168, the problem is it would be an awful amount of work which I don't think anyone is going to do given the small number of people interested in such a thing. At the moment I haven't spent any time optimising it so it only just manages 50-60fps on a high-end desktop.

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Famicom/NES dumps / MiWi2 (VT168) Dumping Attempt
« on: December 20, 2017, 04:03:01 AM »
No worries, I'll probably get one myself as it will would be a useful development platform for testing code if there are ever ambiguities as to what the hardware should be doing.

Although the listing mentions an SD card the Q&A after it says it doesn't have one so I'm not sure what's going on. Perhaps it was removed at the last minute.

It's also interesting - and helpful - that they silkscreened the part number onto the board as none of the systems I have had have that.

Assuming it can run NES and VT03 ROMs that raises interesting thoughts about the architecture of the VT368, and confirms speculation that unlike the VT168 and VT268 it is also backwards compatible with the NES, and must have a mode where NES style sound and video hardware are accessible in the right place.

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Famicom/NES dumps / MiWi2 (VT168) Dumping Attempt
« on: December 19, 2017, 06:50:47 PM »
Yes, that's what I mean by fake cart.

The Lexibook console with ROMs inside sounds awesome, any chance you could send me the suspected VT368 ones? If not don't worry as I'll probably get one myself out of curiosity in the inevitable post Christmas sale on those sorts of things.

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Famicom/NES dumps / MiWi2 (VT168) Dumping Attempt
« on: December 19, 2017, 05:58:38 AM »
The VT268 programming guide (mirrored here) does explain some of these mysteries. I'm not sure about the VT368, as it's not publicly documented, but it can probably be assumed to be an enhanced VT268.

The VT268 does have some high resolution output support, supporting a 512x240 sprite layer AFAICS. This is done with minimal hardware tweaks by having two render paths for each half of the screen. Maybe the VT368 has even more support for high resolution output. Even on the VT268 it might be possible to exploit interlacing to get up to 512x480, maybe that's done badly for some reason explaining the B&W output.

In theory the VT268 only supports 128MBit (16MB) of ROM. This may be higher again on the VT368, or larger ROMs could be connected to the VT368 using GPIO to bank switch the upper address bits. Alternatively some systems use the "fake cartridge" method to switch between ROM banks.

The addressing system of the VT268 is also interesting because instead of the complicated address translation in the VT168, the 6502 CPU has been modified to allow 24-bit addressing directly from the CPU. This unfortunately is documented in a separate document that is not available, however I think it can be reverse engineered easily enough as EmuVT will disassemble all of the new instructions - and I believe it may be similar, at least to some extent, to the 65C816. For use in multicarts and for backwards compatibility with older 6502 code, the VT268 does also support applying a fixed offset to the address.

There are definitely VT268 systems in circulation as Cube Technology claim to have developed games for it.

Hopefully I'll be able to add this to my emulator once the VT168 stuff is working well enough. Then maybe it will be possible to reverse engineer the changes in the VT368 assuming it's not too different from the VT268 (or VT168).




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