Several things

From: Philip.Belben_at_pgen.com <(Philip.Belben_at_pgen.com)>
Date: Thu Apr 15 11:13:22 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.
Received on Thu Apr 15 1999 - 11:13:22 BST