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org
PostPosted: Sun Jan 16, 2022 10:45 pm 
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Joined: Fri Jun 22, 2012 7:39 am
Posts: 201
After many years of research and experiments I think it is time to present you the result - the 6502 simulator (or emulator) on the gate level - Breaks Debugger.

https://github.com/emu-russia/breaks/re ... s-debug-17

(If you're interested you can read the development history of previous versions there)

The Debugger consists of two parts - GUI in c# to display the internals of the processor and native code in c++ which contains the actual emulation of the processor. When you click on the "Step" button, the processor performs one half-cycle and the GUI shows you what's there. The debugger also includes a simple assembler that compiles a 64 Kbyte memory blob at once.

The data flow diagram for the lower part with slight modifications is taken from the dissection of 6502 by ttlworks. Thanks ttlworks! :)

It is possible to dump the internals as Markdown with pictures, for this you need to create a folder WikiMarkdown, where results will be stored.

An example of what results can be seen here: https://github.com/emu-russia/breaks/bl ... /ops/A2.md

Source code of the 6502 emulator here: https://github.com/emu-russia/breaks/tr ... /M6502Core


Attachments:
BreaksDebug_17.zip [712.42 KiB]
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149550095-053e9276-df3b-4868-b8d4-b5987c47209a.png
149550095-053e9276-df3b-4868-b8d4-b5987c47209a.png [ 235.25 KiB | Viewed 4620 times ]
148691773-e7dbd64a-8067-41f2-82c5-94662ee20311.png
148691773-e7dbd64a-8067-41f2-82c5-94662ee20311.png [ 398.52 KiB | Viewed 4620 times ]

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Last edited by org on Fri Jan 21, 2022 5:26 pm, edited 3 times in total.
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org
PostPosted: Tue Jan 18, 2022 12:02 am 
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Fixed the emulation of the tricky S register.

https://github.com/emu-russia/breaks/re ... s-debug-15

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BigEd
PostPosted: Tue Jan 18, 2022 11:09 am 
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It was a great joy to see how the 6502 uses S as a temporary during JSR!
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org
PostPosted: Wed Jan 19, 2022 4:29 pm 
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https://github.com/emu-russia/breaks/re ... s-debug-16

All 6502 instructions are now executed correctly.

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org
PostPosted: Wed Jan 19, 2022 4:49 pm 
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UnitTest Mode

To run the debugger in unit test mode, you need to create a JSON like this:

Code:
json
{
   "CompileFromSource": true,
   "MemDumpInput": "mem.bin",
   "AsmSource": "Test.asm",
   "RamStart": "0",
   "RamSize": "0x800",
   "RomStart": "0xc000",
   "RomSize": "0x4000",
   "RunUntilBrk": true,
   "RunCycleAmount": true,
   "CycleMax": 10000,
   "DumpMem": true,
   "JsonResult": "res.json",
   "MemDumpOutput": "mem2.bin"
}


And run with parameter:
Code:
BreaksDebugger Test.json


As input code, you can use 64 Kbytes memory dump (MemDumpInput) or assembly language source (AsmSource).

Simulator will run until it encounters instruction `BRK` (RunUntilBrk) or specified number of cycles (RunCycleAmount, CycleMax) (These are cycles, not half-cycles).

The output will be a memory dump after simulation (MemDumpOutput) and JSON with simulation results (JsonResult).

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org
PostPosted: Fri Jan 21, 2022 5:16 pm 
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The M6502Core is tested in the Nintendulator:

https://github.com/emu-russia/breaks/re ... s-debug-17

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BigEd
PostPosted: Fri Jan 21, 2022 6:19 pm 
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Oh, do I take it you found a couple of bugs not spotted by Klaus Dormann's test?
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org
PostPosted: Tue Jan 25, 2022 11:43 am 
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Thanks for the tip, I'll check them out too!

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org
PostPosted: Mon Feb 07, 2022 2:50 pm 
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All functional tests of the 6502 by Klaus Dormann are successful.

I ran the unit test with these parameters:

Code:
{
   "CompileFromSource": false,
   "MemDumpInput": "6502_functional_test.bin",
   "AsmSource": "Test.asm",
   "RamStart": "0",
   "RamSize": "0x8000",
   "RomStart": "0xc000",
   "RomSize": "0x4000",
   "RunUntilBrk": false,
   "RunCycleAmount": true,
   "CycleMax": 120000000,
   "RunUntilPC": true,
   "PC": "0x3469",
   "TraceMemOps": false,
   "TraceCLK": true,
   "DumpMem": true,
   "JsonResult": "res.json",
   "MemDumpOutput": "mem_out.bin"
}


The original image was slightly patched (RESET = 0x0400).

The state of the registers and the CLK on the output:

Code:
{"A":"0xF0","X":"0x0E","Y":"0xFF","S":"0xFF","PC":"0x3469","C":1,"Z":0,"I":0,"D":0,"V":1,"N":1,"CLK":96241361}


Attachments:
reset_patch.jpg
reset_patch.jpg [ 335.08 KiB | Viewed 4189 times ]
page_2.jpg
page_2.jpg [ 278.67 KiB | Viewed 4189 times ]
page_0.jpg
page_0.jpg [ 276.96 KiB | Viewed 4189 times ]

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