Re: Hardware emulation of 6509 using 6502?

  (Oops, I see Steve posted while I was typing up a post of my own.   
Luckily I agree with what he's saying, and won't have to alter what I  
already wrote.  :-)

It's worth remembering, as Jim pointed out in a previous post, that we  
haven't gotten the original adapter fully nailed down yet.  Also I  
apologize for implying, even in jest, that we should coax Jim to up  
the ante.  That wasn't fair, especially since he's undertaken so much  
already.  I'm eager to follow the 6502-as-a-6509 project as it  
unfolds, and six years after proposing the circuit maybe I can  
contribute in some further way.

As for '816-as-a-6509, let me ask:  who wants the benefits, and who's  
willing to help?  Mia raised a good point about XOR hardware on the  
bank signals to flip banks around.  Luckily that just means a few  
extra lines of Verilog -- it wouldn't affect the PCB layout.  But my  
point is, there *is* extra work to be done, even just in /defining/  
how the thing ought to behave.  Then later there's testing, and  
possibly feedback for tweaks and improvements.

It's only fair to point out that the benefits are a tad fuzzy so far.   
Can we have a proper talk about that?  For starters, ISTM that what's  
learned from this project could prove invaluable to the remake Mia  
proposes.  As for "more" memory, that in itself isn't really a  
benefit, but *contiguous* memory very definitely can be -- depending  
what code you want to run/write.

Is anyone writing new stuff for CBM?  I'm not a CBM person, and don't  
know.  Someone mentioned SuperCPU.  What's the potential for porting  
existing code from other '816 platforms?  And (back to new stuff for  
CBM), what's the potential for clever kludges and handy helper code?   
Not actual applications; I mean stuff that's not a major job to write  
but is worthwhile to have because it's fun and/or makes life easier.   
Heck, could be as simple as a fast multiplication routine, I dunno --  
that's just an example.  (But it's an example that doesn't pertain to  
memory at all -- in this case it's the 16-bit operations that're the  
attraction.)

6502-as-a-6509 is laying the groundwork.  '816-as-a-6509 takes things  
to another level!

  -- Jeff