Prelim. idea for 68k 'upgrade'...maybe?

[MskoDestny]

Cool idea, but it seems it would be a pain to implement, particularly if you were trying to make it 030 compatible or some other advanced member of the 68K family.  If you don't try to make it compatible with one of those you won't have any software that's designed to run on it.

Also, it seems that the performance gain would be rather small.  You're still limited to about 1 MIP or so.  It seems it would be better to either implement some 68k compatible chip in FPGA or work on some kind of coldfire accelerator rather than trying to hack on extra instructions to the 68000, but perhaps I'm being overly negative about this.

[MskoDestny]

Hacking in an MMU would be a real pains since you would have to mangle the 68K address lines.  Of course, on a Classic Amiga the MMU is arguably much less useful than the FPU.

Modern FPGAs have gotten quite large, of course the more gates they have the more expensive they are.  Still, the original 68K was a relatively simple chip on the grand scale of things and a lot of what makes the later members of the 68K family so complex are more performance related than feature related (particularly on the superscalar 060).

EDIT:
I don't see why you couldn't use one of the Dragonball chips.  All of the extra registers are mapped high in RAM (0xFFFC0000 and above) so only programs that tried to access ROM with an FF in the high bite of the address would have a problem (no idea if this is common).  Of course even the 66MHz can only achieve 10 MIPS, about the same as a 68020 clocked at half that speed.

[MskoDestny]

Programming hardware for FPGAs is quite simple actually.  Generally they're designed to read the configuration from a ROM or SRAM, though I'm pretty sure you can manually program them via a JTAG interface.  There are a few reasons the dev boards tend to be expensive, but a lot of it is that companies that are designing products around these chips can afford to spend that much.

Someone came up with a clever and easy way to solder TSOP and QFP packages with a standard soldering iron.  The original page seems to be gone, but archive.org to the rescue: http://web.archive.org/web/20020806173831/http://warmcat.com/milksop/soldering.html