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Messages - davidstech

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91
Famicom/NES / Work in Progress: new VT168 emulator
« on: December 18, 2017, 05:23:14 PM »
No it's not MAME based at the moment. Would be a possibility for the future though
Some good news. Most of the critical PPU bugs have been fixed, and I've made an initial attempt at implementing the MiWi 2 input (it works but it's quite hacky and the button order isn't correct ATM).

It does now seem to run all of the games I tried without crashing and with some degree of graphics visible, most of the games do still have some PPU issues - mostly due to a bad scrolling implementation.

Hopefully it won't be too long to fix these remaining issues.
Now approximately 90% of the graphical issues are solved. The only games with major issues are the "3D" racing games, I suspect it's due to whatever they use for perspective. Still a bit of work before it's ready to be released, in particular some kind of initial UI and a Windows build.
Public release of version 0.10 posted at the top.

92
Famicom/NES / Work in Progress: new VT168 emulator
« on: December 18, 2017, 01:40:06 PM »
I haven't done any plug'n'plays yet, I should be able to by the new year though. I can dump OneBus cartridges already though. Curious if there are any systems for sale at the moment that people would like to see dumped.
If anyone is curious, would like to help (help reverse engineering the MiWi2 input system would be much appreciated!) or just track progress I've put the source code so far on GitHub

https://github.com/daveshah1/openvtx

Binaries will be published once it's working well enough to release.

93
Famicom/NES dumps / MiWi2 (VT168) Dumping Attempt
« on: December 18, 2017, 01:37:37 PM »
It's certainly annoying that VRT stopped releasing documentation after the VT18/VT32.

I'm focussing this emulator more on the non-NES compatible series at the moment, after the VT168 I'll probably try and start reverse engineering the VT368, which is also undocumented. The last non-NES compatible chip that is documented is the VT268 I think but not on VRT's website only on lcis.com.tw, although I'm not sure whether any known systems use it. Maybe that does mean there's hope other datasheets will leak at some point. I also wonder what would happen if you contacted VRT, ideally under the guise of a company.

94
Famicom/NES / Work in Progress: new VT168 emulator
« on: December 18, 2017, 01:34:06 PM »
The carts were dumped using an incredibly bodged adapter for my universal programmer, I've actually got a PCB ordered that will function as a proper dumper for various systems including the VT168. I'm also planning on building a jig using "pogo pins" for dumping the chip-on-board style ROMs common on plug and play handhelds.

Interesting to see that handheld, it's definitely Sunplus though.

95
Famicom/NES / Work in Progress: new VT168 emulator
« on: December 18, 2017, 01:17:29 PM »
If anyone is curious I've attached some screenshots of the current state of development - at the moment the MiWi2/InterAct input is not emulated so can't get past the title screen.

Attachments:

96
Famicom/NES / Work in Progress: new VT168 emulator
« on: December 18, 2017, 01:14:23 PM »
Yeah maybe once it's done I could turn it into a libretro core then it could be used with RetroArch on Android - then you could use a GPD XD or any Android phone with a gamepad

97
Famicom/NES dumps / MiWi2 (VT168) Dumping Attempt
« on: December 18, 2017, 01:11:02 PM »
Thanks! Both of the InterAct ROMs load in my emulator (although I still haven't sorted out all of the PPU issues yet, the 32-in-1 gives a purple screen) and use the same opcode scrambling as the MiWi2.

At the moment as well as fixing the PPU issues I need to work out how input works on these consoles - both the MiWi 2 and the InterAct seem to use the same system based on their writes to the IO registers, before I can move past the title screen...

98
Famicom/NES / Work in Progress: new VT168 emulator
« on: December 18, 2017, 10:57:12 AM »
I don't think there's ever going to be one for the GBA, buy a GPD Win

99
Famicom/NES / Work in Progress: new VT168 emulator
« on: December 18, 2017, 06:00:29 AM »
Just a heads up on a project I'm working on,Following on from my MiWi2 dumps, which couldn't run in EmuVT because of a bizarre scrambling scheme, I decided it was time to write a new emulator for the later, less NES-based, VT devices starting with the VT168.

The next step after the VT168 is working would be to start adding support for even newer devices, particularly the VT368/VT369. I'm curious whether there are any ROMs suspected to be for these systems floating around, post here or PM me if you have any so I can start looking at reverse engineering those.


Release 0.10 is now public. This will run most of the MiWi2 and InterAct games, but has serious graphical problems in a couple still (mostly the "3D" perspective racing games).

Windows binary download http://davidstech.net/games/openvtx_0.10.zip

Source on GitHub (Windows or Linux) https://github.com/daveshah1/openvtx

MiWi2 ROMs to try out are in the dumping thread. InterAct ROMs are also posted in this thread.

100
Discussion Center / How did you find PGC?
« on: December 17, 2017, 12:43:48 PM »
Pretty sure I first found it while looking for some info on Famiclones on Google many years ago

101
Other Pirates / Waixing's latest Wii clones and APK downloads
« on: December 17, 2017, 04:22:00 AM »
Awesome, thanks for doing this!

Today I was planning on seeing if I can get the games themselves working and maybe capture some screenshots.

Unfortunately the NES romset was nothing special, only 3 files in it weren't in GoodNES and all three were commercial games, so I think nothing more than credit hacks.

102
Other Pirates / Demystifying the 1.8in Handhelds
« on: December 15, 2017, 11:06:15 AM »
Further to my dump a couple of days ago of one of the as-of-yet totally undetermined 1.8in handhelds, I decided to dump another slightly older one, a 106 in 1 I bought from Taobao a few years ago, model number "8533" and PCB date 2013-10-18. You can find the ROM dump here:

http://davidstech.net/games/multis/106%20in%201%201.8in%20DigitalPocket%20Handheld%208533.7z

This time, there are at least some strings in the ROM. At 0x2129 there are the names of all the games, separated by 0xFF. Elsewhere there is other in-game text and also a reference to a hardware test and a checksum.

More interesting there is what is very clearly valid 6502 machine code at various locations in the ROM, the first example I noticed was at offset 0x40436 immediately after the text NS-TOWER and its 0xFF "terminator". This does seem to narrow down the possibilities for what it could be, and also suggests the possibility that it's architecture is somehow derived from the NES. However, I can't immediately find any particularly NES-esque code like writes to the PPU register space. Hence I think it also possible for it to be GameKing derived, as that also had a 6502 based processor.

I can't find obvious assembly in last week's 116in1 ROM dump but given the lack of strings in that dump I think it may be scrambled in some way, which I will investigate further.

I'm going to try and do a bit more research and experimentation, maybe one day we'll have some kind of emulator for these devices.
Well, that was easy, I don't even know why they bothered. The 116in1 dump I last week made was scrambled with the world's best encryption system - XORing with 0xE4... Now strings and assembly are visible and it looks structurally similar to the 106in1, also the name "tony" appears early on - if Tony is reading this, please reply :).

Here's a descrambled version of last week's dump:

http://davidstech.net/games/multis/116%20in%201%201.8in%20Retro%20Pocket%20Games%20(descrambled).7z

A bit more investigation and it appears the code is for the 65C02, not the plain 6502. I can't find anything that points to a particular platform; my best guess now is some generic 65C02 based microcontroller that either has enough RAM that the bootloader copies code from the external SPI flash to RAM, or that supports directly running code off SPI flash.

The LCD display appears to be a generic "microprocessor parallel" type interface so the processor wouldn't necessarily need to have a PPU or display interface if that was done in software. It also seems that the processor might have a speaker driver built in which would narrow the search further.

103
Famicom/NES dumps / MiWi2 (VT168) Dumping Attempt
« on: December 14, 2017, 08:15:30 AM »
It took a bit of fiddling but I did get it to work, from memory I had to set it to VT168, close and reopen it.

Back to the MiWi2, staring at bytes for a bit I think I might know what's going on - bits 7 and 2 are swapped in the opcode but not the operands in the 6502 code. Maybe this is some VT1682 "security" feature, it's certainly weird and doesn't seem to be emulated by EmuVT. I'll investigate further but if EmuVT doesn't support it I'm not sure what can be done really, patching all the 6502 code would be virtually intractable as knowing what is instruction and what is data is nigh impossible.

104
Other Pirates / Waixing's latest Wii clones and APK downloads
« on: December 12, 2017, 11:37:56 AM »
Interesting - I think you're right that your URL is newer as it seems to have everything the other server has and more. Seems just as slow for me unfortunately though.

105
Other Pirates / Waixing's latest Wii clones and APK downloads
« on: December 10, 2017, 07:16:57 AM »
So it seems Waixing/Subor have released a "next generation" Wii knock-off platform that is widely seen across Taobao, continuing from their previous Sunplus SPG293 platform. This time they seem to be running Android with some kind of quad core ARM processor. Models seem to include the ET-71 with camera, Wii-like ET-66 and even the VR Headset (!) ET-79. All of them ship with Wii-style controllers which I think have a proper accelerometer, they certainly look higher quality than the usual knock-off controllers. What's interesting about these is they are actually more powerful than the original Wii, by some margin.

While looking around I found a massive repository of APKs on Waixing's site, at http://www.waixing.com/apk/. The first thing I looked for was a NES emulator, although I found two (and a load of ROMs in the nes subfolder) at http://www.waixing.com/apk/gamenet/app/%E6%A8%A1%E6%8B%9F%E5%99%A8/, I don't think these are much more than NESoid so sadly won't support any WXN games. There are also a large number of presumably Waixing-developed motion games around, it's a very slow server as is often the case so I haven't actually fully downloaded any yet.

At the moment the consoles are about $75, if they drop in price at all I'll probably buy one to investigate a bit more. In the mean time depending on how strict they are about controllers and the platform it may be possible to run the APKs on other Android devices or an Android emulator.

EDIT: I found some technical specifications. The ET-71 has a RK3188 quad-core 1.8GHz CPU, 1GB of RAM and 8GB of Flash. Unfortunately there are no detailed specs the VR headset, I think it's pretty new as it's not widely listed and doesn't even appear on Waixing's website.
Looking through that folder of NES ROMs a bit more thoroughly, I don't think there's anything truly undumped but there are one or two more obscure ones, i.e. 外星战士2 ("Alien Warrior 2") by Waixing (http://www.waixing.com/apk/gamenet/app/%E6%A8%A1%E6%8B%9F%E5%99%A8/nes/%E5%A4%96%E6%98%9F%E6%88%98%E5%A3%AB2.nes).

I suspect there may be more of interest, I'm bulk downloading the folder now the download speed's picked up.

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