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PostPosted: Sun Aug 30, 2020 1:49 am 
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Please, take a look at this taiwanese company, that created a series of 6502 based cheap video games machines.

http://www.vrt.com.tw/product_category.htm

Look at the datasheet of the VT168 series:

- Main CPU: 6502 @5.3693MHz in NTSC and 5.3203MHz in PAL.
- Single 16 bits data bus.
- Enhanced ALU, 16 by 16 multiplier and 32 by16 divider.
- 240 sprites in one frame, 16 sprites in one horizontal line.
- Sound CPU: CPU 6502 @21.4772MHz in NTSC and 26.6017MHz in PAL.


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PostPosted: Sun Aug 30, 2020 2:46 pm 
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Thanks - very interesting.

- dual 6502, but different speeds
- the faster one intended as an audio processor
- microphone input anticipated
- some shared and some private memory
- each 6502 has its multiply/divide peripheral (memory mapped, 6 bytes, with 16 ticks for a multiply)
- 3V operation
- quite impressive PPU for video output
- up to 32M offchip memory
- C compiler available
- emulator available


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PostPosted: Mon Aug 31, 2020 6:32 pm 
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Pretty interesting. It is somewhat reminiscent of the SNES, but lacking a number of features and sharing the bus instead of fully dedicated VRAM (this chip intends to have the actual pixel definitions stored in off-chip memory, stealing bus bandwidth from the CPU).

I presume the main way to get access to one of these chips is to find some mass-market trinket and dissect it.

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AcheronVM: A Reconfigurable 16-bit Virtual CPU for the 6502 Microprocessor


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PostPosted: Mon Aug 31, 2020 7:46 pm 
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Hi!

White Flame wrote:
Pretty interesting. It is somewhat reminiscent of the SNES, but lacking a number of features and sharing the bus instead of fully dedicated VRAM (this chip intends to have the actual pixel definitions stored in off-chip memory, stealing bus bandwidth from the CPU).

I presume the main way to get access to one of these chips is to find some mass-market trinket and dissect it.

It is available as the "worst console ever", the MiWi 2: https://www.youtube.com/watch?v=K0-NdIcjmCE

Note that the CPU is not binary compatible with the 6502, it swaps bits of the opcode, there is some details in forums like http://bootleg.games/BGC_Forum/index.php?topic=1743.0

Have Fun!


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PostPosted: Mon Aug 31, 2020 8:01 pm 
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(Just to note: "worst console ever" could be a matter of software deficiency, I suppose?)


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PostPosted: Mon Aug 31, 2020 8:12 pm 
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From the video, it's the software but also really poorly construction and misrepresented-by-design peripherals. The chip offers stereo, while the console only outputs mono. There's no reason the chip itself couldn't run really good games or be part of an interesting cheap gamedev kit.

Is VRT still around? The most recent date on their website seems to be 2009.

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AcheronVM: A Reconfigurable 16-bit Virtual CPU for the 6502 Microprocessor


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PostPosted: Mon Aug 31, 2020 8:16 pm 
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The architecture is within the reach of an FPGA, except for the ADC aspects.


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