It is not the point that replica behaves "perfectly same", the issue is that they are not period accurate. Even it is a perfectly But also keep in mind that t

It is not the point that replica behaves "perfectly same", the issue is that they are not period accurate. Even it is a perfectly But also keep in mind that there is no such a thing as a "digital circuit" in physical world, because there some analog effects at work in any digital circuit. If it were not true, the would not have been hardware incompatabilities seen even in moderrn systems, which often happen due timing/delay or noise issues. WRT to retro tech, in for example Apple-I modern 74hct/act chips would not often work compared to more humble 74ls chips. There are also interesting temperature-dependent effects in NMOS 6502 (some undocumented instructions are executed differently) which have non-digital reasons and cannot be reproduced. Emulators are a lot easier btw to write than a VHDL or verilog spec and put it to actual hardware and debug etc, due to having already so many existing open source code for emulators, processors etc. My point is different though - there is no way to make new Commodore 64 out of existing components. What you will get is a faithful replica with zero historic importance. For some it does not matter, but I still believe that even these people make a majority, the resulting product is not C64 and should not be called such.