Someone for finish Universal PPU project (FPGA for real NES)

A place where you can keep others updated about your NES-related projects through screenshots, videos or information in general.

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lidnariq
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Re: Someone for finish Universal PPU project (FPGA for real

Post by lidnariq » Wed Jan 23, 2019 11:26 am

tepples wrote:except for games that explicitly SED or PLP a value with bit 3 true. Do any exist?
NewRisingSun has found some games for famiclones that explicitly use decimal mode ... which would therefore actually work correctly here.

tepples
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Re: Someone for finish Universal PPU project (FPGA for real

Post by tepples » Sun Nov 10, 2019 9:06 am

I found this topic while cleaning out my PMs, via Fisher's post:
lidnariq wrote:If you're smart enough to understand how to write LaTeX, you're smart enough to teach yourself Verilog.
One can usefully learn and use LaTeX with only a personal computer, which anyone here who isn't mobile-only already has. As I understand it, using Verilog additionally requires the purchase of an FPGA dev board and/or PCB manufacturing services, which could be beyond the budget of an un- or underemployed member of this board. Or are free or freeware Verilog simulators fast and accurate enough that one can usefully rely on simulation?

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Memblers
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Re: Someone for finish Universal PPU project (FPGA for real

Post by Memblers » Sun Nov 10, 2019 6:23 pm

tepples wrote:Or are free or freeware Verilog simulators fast and accurate enough that one can usefully rely on simulation?
Verilator seems pretty darn good. https://8bitworkshop.com/ is a quick and easy way to try it out. On the platforms, select Hardware / Verilog. Includes audio and video output.

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Re: Someone for finish Universal PPU project (FPGA for real

Post by NewRisingSun » Mon Nov 11, 2019 1:50 am

The original 60-pin releases of Bit Corporation's "Duck Maze" and "Othello" enable Decimal Mode via SED and use it to display the on-screen game state. In the absence of Decimal Mode, the games will display garbage in the score and number of pieces display. Depending on the current score, "Duck Maze" will never finish counting down at the end of a level. The 72-pin releases by Home Entertainment Suppliers (HES) have been updated to work on a standard NES 2A03.

On the other hand, Solar Jetman inadvertently enables Decimal mode by corrupting the flag byte that resides on the stack. If Decimal Mode is emulated, the game will quickly crash or exhibit other aberrant behavior at the title screen. Using a MOS 6502 CPU would therefore break this game.

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