VT09 RAM

Discuss emulation of the Nintendo Entertainment System and Famicom.

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NewRisingSun
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VT09 RAM

Post by NewRisingSun » Wed Nov 22, 2017 5:13 am

The VT09 variant of the OneBus-type Famiclones has 4 KiB instead of 2 KiB of main CPU RAM at offset $0000 in CPU memory. FCEUX apparently uses mapper 256 for OneBus, and I intend to follow that precedent. In the NES 2.0 format, should this additional RAM be denoted as a submapper or as 2 KiB PRG-RAM, even though this additional RAM is part of the main unit (or rather part of the main chip) and not the game? Some OneBus images of course have the normal 8 KiB of WRAM at $6000, so if one went for the PRG-RAM field, the PRG-RAM size would then implicitly determine its offset as well, which seems kind of hacky to me. Given that several OneBus images are multicarts consisting of NES-era games that may depend on RAM being mirrored four times in the $0000-$1FFF range, just always emulating the additional 2 KiB does not seem safe.

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lidnariq
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Re: VT09 RAM

Post by lidnariq » Wed Nov 22, 2017 5:22 am

Most of the fields in the NES2.0 header are describing properties of the cartridge, not the console. And if you use the RAM size field here to describe the console, there's no space to describe the cartridge.

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Dwedit
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Re: VT09 RAM

Post by Dwedit » Wed Nov 22, 2017 3:22 pm

The VS system and PAL region flags describe the console, and not the game.
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zzo38
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Re: VT09 RAM

Post by zzo38 » Sat Nov 25, 2017 7:53 pm

Dwedit wrote:The VS system and PAL region flags describe the console, and not the game.
Yes. If there are unused bits in those section, then maybe use some of those if necessary?
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kelvin donna
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Re: VT09 RAM

Post by kelvin donna » Sat Jan 16, 2021 1:48 pm

NewRisingSun wrote:
Wed Nov 22, 2017 5:13 am
The VT09 variant of the OneBus-type Famiclones has 4 KiB instead of 2 KiB of main CPU RAM at offset $0000 in CPU memory. FCEUX apparently uses mapper 256 for OneBus, and I intend to follow that precedent. In the NES 2.0 format, should this additional RAM be denoted as a submapper or as 2 KiB PRG-RAM, even though this additional RAM is part of the main unit (or rather part of the main chip) and not the game? Some OneBus images of course have the normal 8 KiB of WRAM at $6000, so if one went for the PRG-RAM field, the PRG-RAM size would then implicitly determine its offset as well, which seems kind of hacky to me. Given that several OneBus images are multicarts consisting of NES-era games that may depend on RAM being mirrored four times in the $0000-$1FFF range, just always emulating the additional 2 KiB does not seem safe.
but when i try to play an VT03 or VT09 game such as: Access Block or Bubble Blaster in FCEUX, then the game won't work.
may i get some advice on how to make the games work on FCEUX?

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Quietust
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Re: VT09 RAM

Post by Quietust » Sat Jan 16, 2021 2:10 pm

Might I suggest finding a VT03/VT09 emulator rather than using an NES emulator?

Also, did you really need to resurrect a 3+ year-old thread rather than posting in the VTxx thread you already made?
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kelvin donna
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Re: VT09 RAM

Post by kelvin donna » Sun Jan 17, 2021 7:55 am

Quietust wrote:
Sat Jan 16, 2021 2:10 pm
Might I suggest finding a VT03/VT09 emulator rather than using an NES emulator?

Also, did you really need to resurrect a 3+ year-old thread rather than posting in the VTxx thread you already made?
sadly, there is no VT03 Emulator for Retrofw or the Miyoo CFW, whereas FCEUX is the one, who got ported to both of those systems.

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