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Creating a C64 emulator in GameMaker - Part 3

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#1 Mike.Dailly


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Posted 16 January 2015 - 04:35 PM



In this part I want to talk first about the CPU bug I had, and how I fixed it, then I want to discuss the C64's memory mapping system, and how I deal with rapid paging on a per instruction basis.


So the problem with CPU bugs, is that you have very subtle bugs that only show themselves on the 10 or 20 thousandth instruction. Now, you can either step through everything using a 6502 debugger (which you'd also have to write and debug first!), and see at what point it goes wrong, or you can think outside the box a little...


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#2 kabecao


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Posted 16 January 2015 - 07:29 PM

I'm following a similar process for a Gameboy emulator besides the C64.

It also serves to show how the new debugger is much more useful than the old one particularly the watcher, buffer view and breakpoints in this case.


I using draw_point to parse the graphics RAM to a surface but is really slow.

buffer_set_surface is not working yet and shader does't allow big arrays.

How will you implement this?

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