Scanning the original chips

[psxphill]

Getting the exact internal microcode (note, it is split into two tables to compress it) will be very interesting and reduce the size of the softcores considerably.

I thought we had the microcode already, I'll ask around in case it's not public yet.
 
You can find the microcode in the 68000 patent, but we know it's got some wrong values.

[psxphill]

Let me know if you have it.
I have the details from the patents, but it's not terribly useful.
With the die scan we can see how the ops are decoded. It's a very neat design, all of the "strangeness" comes out as a result of implementation.
/MikeJ

All I've dug out of my email archives so far is an email from Nick Tredennick.
 
> The best description of the internal workings of the MC68000 can be found in Chapter 11 of Francois Anceau's
> textbook The Architecture of Microprocessors. It does, however, contain a few errors.


The guy we use for decapping is MIA (we don't pay him anywhere near as much as he gets paid for real work, so it's pretty understandable). So it might still be sitting in his queue all these years later.
 
You probably don't want to implement the 68000 microcode though as the ALU was 16 bit, so performance wouldn't be that great. Cycle accuracy of the CPU on the Amiga was never that necessary, however for Atari ST emulation you really need it if you want to get all demos working.
 
If you just want it for inspiration then the book and patent are more likely to be useful. Otherwise it might be better to get a 68020 decapped.

[psxphill]

This begs the question if you committed to producing at least a million units minimum how much it would cost per unit to produce a working 100% compatible classic Amiga motherboard of A500 and A1200 specs?

It doesn't beg the question.
It raises the question. http://en.wikipedia.org/wiki/Begging_the_question
 
If you wanted to make it as cheap as possible, you want as few components as possible and a board just big enough for the io connectors.
Something like an fpgaarcade in a different form factor.
 
To make something that looks like an a500 is going to be pretty expensive because of all the sockets and chips. It was designed at a time when commodore made all of their own stuff, so it fit in with what they could do as cheaply as possible (I doubt for instance that the Amiga design included 2x MOS CIA's before commodore bought Amiga Inc).