13 May
2018
13 May
'18
9:30 p.m.
From: Clem Cole
Their is a open question about the need to support
self modifying code
too. I personally don't think of that as important as the need for
conditional instructions which I do think need to be there before you
can really call it a computer.
Here's one way to look at it: with conditional branching, one can always
write a program to _emulate_ a machine with self-modifying code (if that's
what floats your boat, computing-wise) - because that's exactly what older,
simple microcoded machines (which don't, of course, have self-modifying code
- their programs are in ROM) do.
Noel
13 May
13 May
9:44 p.m.
New subject: The birth of the Z3
On 05/13/2018 05:30 PM, Noel Chiappa wrote:
Rewording that, as I recall from Computability Theory there are three
statements needed for Turing completeness:
1. S <- 0 S is some var
2. S <- S + 1
3. if S=0 goto L L is some line#
Beyond that everything else is icing on the cake. Kind of like needing
nothing more than a bunch of NAND gates to build a computer,
disregarding practicality...
Mike Markowski
From: Clem
Cole
Their is a open question about the need to
support self modifying code
too. I personally don't think of that as important as the need for
conditional instructions which I do think need to be there before you
can really call it a computer.
Here's one way to look at it: with conditional branching, one can always
write a program to _emulate_ a machine with self-modifying code (if that's
what floats your boat, computing-wise) - because that's exactly what older,
simple microcoded machines (which don't, of course, have self-modifying code
- their programs are in ROM) do.
Noel 
14 May
14 May
3:27 a.m.
New subject: The birth of the Z3
On Sun, 13 May 2018, Mike Markowski wrote:
Beyond that everything else is icing on the cake.
Kind of like needing
nothing more than a bunch of NAND gates to build a computer,
disregarding practicality...
Or a bunch of NOR gates, which are equivalent :-) I'd demonstrate the
proof here, but my TeX skills aren't up to it...
-- Dave
2309
days inactive
2310
days old
2 comments
3 participants
participants (3)
-
Dave Horsfall -
jnc＠mercury.lcs.mit.edu -
Mike Markowski