Several things - test-drb@ccmp.vtda.org

15 Apr 1999

...
 > Fair enough.  Just another example of different
places to draw boundaries, with
...
 > grey areas in between.  I would call the ROM
version microcoded, and the hard
> wired version not, because the ROM version contains CODE.  (I would agree that
...

 I think a lot of people would. I just have problems distinguishing them
 in the first place.

 This might be because I've worked with FPGAs where the logic block (5
 inputs 1 out) is a 32 bit RAM. I give my schematic to the FPGA compiler
 and it partitions the logic into suitable bits and works out what to
 stick in the RAMs to make the gates I need. Since I always checked (and
 sometimes corrected) what the compiler had done, I got used to thinking
 of combinatorial logic and programmed memories as being roughly the same
 thing. 

Makes sense.  Another grey area.  I must admit that I too would call that
microcode.  This is reminiscent of the famous analogu/digital grey area...

...
 > To show how grey this is, if you use a ROM to
implement the combinatorial logic
...
 > for a flipflop-per-state machine, would you call
the code in this ROM microcode?
...

 Hmmm... Now you mention it, I guess I have to call that microcode. I'm
 therefore inconsistent... 

I wouldn't worry about it.  Goedel's theorem says that if you weren't,
you'd
have to be incomplete :-)

Philip.