Lies, damn lies!

Jecel Assumpcao Jr jecel@lsi.usp.br
Thu, 27 May 1999 13:30:31 -0300


Laurent Martelli wrote:
>   Jecel> Now you got me really confused! Every explanation I have ever
>   Jecel> seen of Turing Machines have always presented them with a
>   Jecel> Harvard Architecture instead of a Von Neumann one: they store
>   Jecel> their state in an infinite tape of symbols and their code in
>   Jecel> a separate table representing a finite state machine. Only
>   Jecel> the tape can be accessed and changed, not the table.
> 
> Code is data, and data is code. The data on the tape can be considered
> a source to be interpreted by the state machine.

I admitted that, but asked how is this different from simulating a
Z80 computer running Forth in, for example, Pascal? Faré seemed to
be rejecting the "interpreter" definition of universality, but in
that case a Turin Machine is no longer universal as far as I can see.

-- Jecel