SimpleNES -- An NES emulator in SFML and C++!
A few years ago (when I was but a newbie) I read a thread on this forum (http://www.cplusplus.com/forum/lounge/106729/ ) which inspired me to make an NES emulator in C++!
The Github repo: https://github.com/amhndu/SimpleNES
Project page: http://amhndu.me/Projects/nes-emu.html
(Links to download and other information here).
They have screenshots and here's playlist on YouTube: https://www.youtube.com/playlist?list=PLiULt7qySWt2VbHTkvIt9kYPMPcWt01qN
Just wanted to share with you guys Thanks Disch for suggesting this!
The Github repo: https://github.com/amhndu/SimpleNES
Project page: http://amhndu.me/Projects/nes-emu.html
(Links to download and other information here).
They have screenshots and here's playlist on YouTube: https://www.youtube.com/playlist?list=PLiULt7qySWt2VbHTkvIt9kYPMPcWt01qN
Just wanted to share with you guys Thanks Disch for suggesting this!
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Cool. Do you make any attempts at cycle-accurate timing, or do you stop at instruction-accurate timing?
I'm not exactly sure what is the difference...
In the CPU, the instructions are carried out in one go and the CPU just stays idle for the rest of the instructions cycles instead of performing the appropriate reads/write at individual cycles. Is this what you meant ?
In the CPU, the instructions are carried out in one go and the CPU just stays idle for the rest of the instructions cycles instead of performing the appropriate reads/write at individual cycles. Is this what you meant ?
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I'm not sure what that means either. Is cycle-accurate where instructions at executed at about the same rate they'd be executed on the original machine?
Imagine the system has a second chip that runs on the same clock as the CPU but can access memory and operate independently of the CPU. Suppose:
1. At clock 1000 an instruction will execute that takes 4 clocks.
2. The instruction will write to address 0xCD04 at clock 1003.
3. The second chip will read address 0xCD04 at clock 1002.
An instruction-accurate emulator would execute all side-effects of the instruction instantly, then the second chip will see the updated value of 0xCD04, when in a real system it would have seen the old value. The speed of the CPU will still be emulated, and the next instruction will execute at clock 1004.
A clock-accurate emulator would execute instruction side-effects at the correct clocks, like a real system would.
1. At clock 1000 an instruction will execute that takes 4 clocks.
2. The instruction will write to address 0xCD04 at clock 1003.
3. The second chip will read address 0xCD04 at clock 1002.
An instruction-accurate emulator would execute all side-effects of the instruction instantly, then the second chip will see the updated value of 0xCD04, when in a real system it would have seen the old value. The speed of the CPU will still be emulated, and the next instruction will execute at clock 1004.
A clock-accurate emulator would execute instruction side-effects at the correct clocks, like a real system would.
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