Re: 6502 illegal opcodes questions

[Bruce Tomlin <bruce#fanboy.net@127.0.0.1>]

In article <e53i7m$1set$1@merope.saaf.se>,
 pausch@saaf.se (Paul Schlyter) wrote:

> The Java platform doesn't exist in hardware - it must be simulated
> in software.  "But that means Java is portable: I can run my JVM on

I thought Java bytecodes, or at least a significant portion of them, 
actually had been implemented in hardware.  But I know for certain that 
UCSD P-code had been implemented in hardware once at least once in the 
mid '80s.  I think it was called the "P-Engine", and Jerry Pournelle 
mentioned it in his column in Byte.

Likewise, I recall that a significant portion of Smalltalk bytecodes and 
primitives were implemented in hardware at Xerox, using the Dorado's 
capability for downloadable microcode.

So just because someone makes up an instruction set for a virtual 
machine doesn't mean that it can't (or won't) be implemented in 
hardware.  There may be a few of the more complicated instructions that 
have to be trapped out and implemented in terms of the less complicated 
instructions, but if someone feels a need to do so, it can get 
implemented in hardware.  (So when is someone going to take up the 
challenge and implement Zork's instruction set in VHDL?)