Various questions

[John Morrison]

Hi;

Emmanuel Rialland wrote:
> I know that those questions could sound provocative and but here we
> are:
> 
> 1) why C++?
> why not lisp / scheme / OCaml or anything else (I remember
> that simh was mentionned).

Easier to put on raw hardware.  If we were doing this in Lisp, and
didn't care so much about a Lisp OS, putting more work into CMUCL/SBCL
and gutting a Linux distro might be the way to go.

> I readily admit my brains melt reading the current code. I don't understand a
> lot of it.

Join the club.

> 2) most of the game consoles emulators developers like to put some sort of
> "dynarec engine" (dynamic recompilation)?
> I read some pages of this link
> http://acorn.cybervillage.co.uk/emulation/dynrcomp.htm

"Dynamo" was one that I remember reading about.  It would be nice to
try.

> Looks good, fancy and complicated.
> Has anybody wondered about that too? Pushing the enveloppe I could imagine
> Open Genera for Alpha running on a reverse fx32 (alpha library to run i386
> code) running on a Transmeta.

At one point in the distant past, when I first heard about Transmeta's
approach, and before I knew they weren't going to let us open the hood
beneath the x86 layer, I was hoping we could build a Nouveau(x?/elle?)
LispM on it.  It seemed the parallel (VLIW, or so I thought) type
execution units could speed up some tag-checking and other stuff.

Two other approaches that piqued my curiousity were:

(a) FPGA-based PCI form-factor daughter boards for PCs.  Apparently
there are such beasts, complete with PC-based design tools that let you
roll your own custom CPU.  With a little bit of "life support" software,
you could have a Return of the Son of MacIvory (PC rather than Mac).

(b) A "soft" CPU (I forget the manufacturer), which was a sort of RISC
part implemented inside of a single FPGA with lots and lots of extra
gates unused, with tools to let you roll your own co-processor out of
the remaining gates.  The RISC part would become the New FEP, and you
could configure a Lisp processor on the same chip with the unused
gates.  It also came mounted on a reference board, to ease development.

Ah, well.  Pipe dreams...

-jm


-- 
==== John Morrison
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