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39 lines
1.5 KiB
Markdown
39 lines
1.5 KiB
Markdown
# puce6502
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This is a simple and readable emulation of the MOS 6502 CPU\
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It passes the [Klaus Test Suite](https://github.com/Klaus2m5/6502_65C02_functional_tests), implements all original instructions and is cycle accurate excepted for :
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*Absolute-X, absolute-Y, and Zero page-Y addressing modes which need an extra cycle if indexing crosses a page boundary, or if the instruction writes to memory.*
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You can easely interface it with your code using :
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```
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void puce6502Reset();
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void puce6502Exec(long long int cycleCount);
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```
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The first emulates a reset signal, the second will execute as many instruction as needed to reach cycleCount
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RAM and ROM are implemented using 8 bits integer arrays. And are directly accessible to your code to load ROM binary images and, for example, generate video output\
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RAM starts at adress 0x000\
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Update the three #define to adapt the ranges to your needs :
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```
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#define ROMSTART 0xD000
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#define ROMSIZE 0x3000
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#define RAMSIZE 0xC000
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```
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You are expected to provide a function to handle read and writes to locations not in ROM or in RAM (for Soft Switches, extension cards ROMs, PIA, VIA, ACIA etc...)
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```
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extern uint8_t softSwitches(uint16_t address, uint8_t value);
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```
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Finally, the variable `ticks` is a long long int holding the number of cycles since last reset.
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For an example of use, you can refer to [reinette II plus](https://github.com/ArthurFerreira2/reinette-II-plus) a french Apple II plus emulator.
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Have fun !
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