300-in-1 SY-889 Handheld Dump (VTxx)

Joined: January 29th, 2011, 5:49 pm

January 12th, 2018, 2:55 pm #1

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- ... 0flash).7z
300_in_1_NES_based_handheld__SY_889__W25Q64_serial_flash_.png
300_in_1_NES_based_handheld__SY_889__W25Q64_serial_flash_.png
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Joined: January 3rd, 2015, 4:40 pm

January 12th, 2018, 3:43 pm #2

Thank you davidstech! :D
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Joined: February 17th, 2017, 12:59 am

January 12th, 2018, 9:27 pm #3

How odd. It writes to $411C, setting the VT16+ bits for EX2412EN and IRQVS, but the acts as if it didn't. I don't know what's going on with the palette at all.

Can you post one picture each of of the dancing cats, the language select, and the Chinese and English menu screen, just so I know what it's supposed to look like?
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Joined: January 29th, 2011, 5:49 pm

January 12th, 2018, 9:53 pm #4

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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Joined: February 17th, 2017, 12:59 am

January 12th, 2018, 10:06 pm #5

It runs well in my Nintendulator build if I ignore the 411C write, apart from the menus colors being wrong, and the IRQs firing somewhat too soon. I can get the menu palette closer to being meaningful if I interpret the bits as direct RGB bits, rather than VRT's method described here, although it's not perfect.

I would say it's a clone of the VT03. That would explain the odd IRQ behavior as well as the $411C write having not the meaning that VRT described in their VT16 and VT18 manuals. Are the square wave duty cycles as they are on an original NES, or are they swapped? Because original VRT chips always swap the 50% and 25% duty cycles, so if they are as on the original NES, it can't have been made by VRT.
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Joined: January 29th, 2011, 5:49 pm

January 12th, 2018, 10:34 pm #6

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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Joined: February 17th, 2017, 12:59 am

January 12th, 2018, 11:00 pm #7

Here is how my emulation looks right now:




The first three look somewhat plausible, but the last one looks odd. Judging by similar multicarts, the background should be blue, not gray, and the lowest parts of "N" and "1" look incorrect as well.

I just noticed that the palette format that I am emulating for this cart resembles the VT168's... :unsure:
And the IRQs seem to be expected one scanline earlier, but 32 or so PPU clocks later, than a standard VT03 (or MMC3, for that matter).

All of these changes would of course break existing VT02/VT03/VT09 games, although I could implement both, and use the very first register write that the game makes ($01 to $4304) to tell them apart.

NES 2.0 headers are nice, but Nintendulator should load the .BIN file just fine. The NES 2.0 header would have to specify mapper 256, and 4 KiB of PRG-RAM (possibly just 2 KiB, but they would then have to start at $6400, which is implausible).
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Joined: January 3rd, 2015, 4:40 pm

January 13th, 2018, 12:44 am #8

How do you make those screenshots if Nintendoulator does not have such a function?
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Joined: January 29th, 2011, 5:49 pm

January 13th, 2018, 11:20 am #9

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.






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".
cats.jpg
menu_en.jpg
langsel.jpg
menu_cn.jpg
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Joined: February 17th, 2017, 12:59 am

January 13th, 2018, 12:07 pm #10

Oh, so the emulation is right, and the graphics are just ugly. Okay. :) Thank-you for the pictures.

I have implemented support for this chip variant in Nintendulator, distinguished from VT03 et al. via the $4304 write.

Oh, one more thing: Game #41 is Sachen's "Magic Mathematic". If you let the Title Screen run, there should be a scrolling glitch because they used the PAL version of the game. Can you confirm that? (If not, then the console does not use NTSC timing.)
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