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Comment by glandium | Hacker News Reader

This makes me wonder. The 6502 in the NES ran at 1.79MHz.

According to https://en.wikipedia.org/wiki/Instructions_per_second , a modern i7 processor handles north of 100,000 MIPS.

According to https://en.wikipedia.org/wiki/Transistor_count, the 6502 had 3510 transistors.

At 100,000 MIPS, a modern CPU would have a budget of ~56k instructions to process one cycle of that CPU, or about 16 instructions per transistor.

So it would seem it might now be possible to simulate those old processors, at the transistor level, in real time. Is anyone aware of experiments in this domain? If not really useful, that sounds like an interesting fun (side) project.

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http://www.visual6502.org/ does it in the browser & flashes transistor states at you!

And if you liked that you'll probably also enjoy http://www.megaprocessor.com/progress.html

Also: Introducing the MOnSter 6502 http://www.evilmadscientist.com/2016/6502/

This is incredible! But it's also nowhere near realtime. The max clock rate of a 6502 is 1 MHz to 2 MHz, while the simulation runs at around 7.3 Hz in my browser.

It turns out that for several reasons, creating an exact emulation of even much older gaming technology can be very computationally intensive.

http://arstechnica.com/gaming/2011/08/accuracy-takes-power-o...

When people link to this, it's a good idea to mention that 65816 emulation runs as one enormous switch statement. Yes, it's accurate, but at a rather large performance penalty.

I'm a daily/weekly higan user, nut I make no excuses for how it's written. take a peek into the code.

I'm aware that hardware simulation of processors is something which is done, particularly by the people who design those processors.

It takes a lot of grunt to simulate a modern GPU or CPU, and of course getting near realtime is impossible, but it's handy if you want to run a load of code through it to see if it actually works.

So... yes, you can unit test the design of your processor. If you have a big enough server farm.

Verilog does exactly this. You design the logic than simulate all the gates. I'm sure there's some open cores out there ready for simulation if someone wants to fiddle with it

Simulations of complex modern chips don't run in real time.

You might find ladder logic for PLCs interesting. It simulates old hardware relay systems.

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