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PostPosted: Fri Feb 23, 2018 2:27 pm 
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It seems that for all these 10 years of knowledge of NES I've been thinking that the NES's CPU is 6502 and that the NES's APU is 2A03, but it seems I was wrong! It's the same chip! But how is that possible? How could they have all those sound registers and sound logics together with the 6502 core? How is that possible? Did they have 2 dies in the same chip tray? (jk, I know they didn't. (or did they?))
It seems I've been underestimating this chip so much. I kinda wish to have such a chip for to make my own console like the NES, except it'd be beefed up like having 1 cycle for the indirect indirect indexing and 3 24-bit registers for indirection like AVR XMEGA microcontrollers. Wow... Is there an FPGA board I can buy and a free commercial use allowing FPGA editor and an MIT-licensed NES clone FPGA file (however it's called) so that I can make my own NES, but with lots of more capabilities?


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PostPosted: Fri Feb 23, 2018 2:47 pm 
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Knock yourself out: http://www.qmtpro.com/~nes/chipimages/visual2a03/


The current state of the art of libre toolchains for FPGAs is what's provided by YOSyS


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PostPosted: Fri Feb 23, 2018 3:05 pm 
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Yes, they are.

As for how it is possible, it's extremely simple, they just put logic for both the CPU and the APU in the same chip. Today we could easily fit the entiere console in a single chip, and that's even exactly how the NOAC (NES-on-a-chip) clones are made.


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PostPosted: Fri Feb 23, 2018 3:23 pm 
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8bitMicroGuy wrote:
Did they have 2 dies in the same chip tray? (jk, I know they didn't. (or did they?))

If you take a look at the Visual2A03 link lidnariq provided, you can see a shrunk down 6502 taking up the bottom right quadrant.

You can compare it with the Visual6502:
http://www.visual6502.org/JSSim/index.html


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PostPosted: Fri Feb 23, 2018 4:12 pm 
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rainwarrior wrote:
8bitMicroGuy wrote:
Did they have 2 dies in the same chip tray? (jk, I know they didn't. (or did they?))

If you take a look at the Visual2A03 link lidnariq provided, you can see a shrunk down 6502 taking up the bottom right quadrant.

You can compare it with the Visual6502:
http://www.visual6502.org/JSSim/index.html

In fact, you can directly compare it with Visual6502, because it's exactly the same - rather than trace out the entire 6502 inside the RP2A03G (and make a bunch of hard-to-find mistakes like I did with the rest of the 2A03), I got lazy and copy/pasted the Visual 6502 into Visual 2A03 and spliced the two designs together.

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PostPosted: Fri Feb 23, 2018 6:17 pm 
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That site crashed my laptop when I tried to zoom in and out.


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