[TUHS] The birth of the Z3

[TUHS] The birth of the Z3

[Noel Chiappa]

    > 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

[TUHS] The birth of the Z3

[Mike Markowski]

On 05/13/2018 05:30 PM, Noel Chiappa wrote:
>      > 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

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

[TUHS] The birth of the Z3

[Dave Horsfall]

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

[TUHS] The birth of the Z3

[Clem cole]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 2160 bytes --]

Yes of course.  I used to program the 8 so I remember.  But I (sloppily) think of them the same way although you are correct they are different in implementation.  But my key point is until conditional instructions that change the path come along we are not to the general purpose computing platform.  

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.   But that’s my opinion and others clearly believe neither are needed.  

Clem

Sent from my PDP-7 Running UNIX V0 expect things to be almost but not quite. 

> On May 13, 2018, at 2:52 AM, Greg 'groggy' Lehey <grog at lemis.com> wrote:
> 
>> On Saturday, 12 May 2018 at 11:04:26 -0400, Clem Cole wrote:
>>> On Fri, May 11, 2018 at 6:21 PM, Dave Horsfall <dave at horsfall.org> wrote:
>>> 
>>> Way back on this day in 1941, Conrad Zuse unveiled the Z3; it was the
>>> first programmable automatic computer as we know it (Colossus 1 was not
>>> general-purpose).  The last news I heard about the Z3 was that she was
>>> destroyed in an air-raid...
>>> 
>>> This pretty much started computing, as we know it.
>> 
>> But .. until we also include a conditional branch the ability to do
>> self modify code we don't really have the machine with think of as
>> the automatic programmable computer.
>> 
>> Check out:
>> http://page.mi.fu-berlin.de/rojas/1993/Who_invented_the_computer.pdf its a
>> fun read.
> 
> That's an interesting document, but it refers to the Z1, not the Z3.
> But Wikipedia confirms that the Z3 also didn't have conditional
> instructions.
> 
> Conditional branch is only one way to do that, of course.  The PDP-8,
> for example, didn't have one, just (like many machines of the day)
> conditional skip instructions.
> 
> Greg
> --
> Sent from my desktop computer.
> Finger grog at lemis.com for PGP public key.
> See complete headers for address and phone numbers.
> This message is digitally signed.  If your Microsoft mail program
> reports problems, please read http://lemis.com/broken-MUA

[TUHS] The birth of the Z3

[Greg 'groggy' Lehey]

On Saturday, 12 May 2018 at 11:04:26 -0400, Clem Cole wrote:
> On Fri, May 11, 2018 at 6:21 PM, Dave Horsfall <dave at horsfall.org> wrote:
>
>> Way back on this day in 1941, Conrad Zuse unveiled the Z3; it was the
>> first programmable automatic computer as we know it (Colossus 1 was not
>> general-purpose).  The last news I heard about the Z3 was that she was
>> destroyed in an air-raid...
>>
>> This pretty much started computing, as we know it.
>
> But .. until we also include a conditional branch the ability to do
> self modify code we don't really have the machine with think of as
> the automatic programmable computer.
>
> Check out:
> http://page.mi.fu-berlin.de/rojas/1993/Who_invented_the_computer.pdf its a
> fun read.

That's an interesting document, but it refers to the Z1, not the Z3.
But Wikipedia confirms that the Z3 also didn't have conditional
instructions.

Conditional branch is only one way to do that, of course.  The PDP-8,
for example, didn't have one, just (like many machines of the day)
conditional skip instructions.

Greg
--
Sent from my desktop computer.
Finger grog at lemis.com for PGP public key.
See complete headers for address and phone numbers.
This message is digitally signed.  If your Microsoft mail program
reports problems, please read http://lemis.com/broken-MUA
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 163 bytes
Desc: not available
URL: <http://minnie.tuhs.org/pipermail/tuhs/attachments/20180513/4fffeb86/attachment.sig>

[TUHS] The birth of the Z3

[Clem Cole]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 2452 bytes --]

On Fri, May 11, 2018 at 6:21 PM, Dave Horsfall <dave at horsfall.org> wrote:

> Way back on this day in 1941, Conrad Zuse unveiled the Z3; it was the
> first programmable automatic computer as we know it (Colossus 1 was not
> general-purpose).  The last news I heard about the Z3 was that she was
> destroyed in an air-raid...
>
> This pretty much started computing, as we know it.


​Again be careful -- we don't want to go down that rat hole.   There has
been always been an argument since it (as well as Atanasoff and Aiken's
machines all) lacks a conditional branch.    Although, I do believe some
one the UK proved the Z3 to be Turing complete; but the argument will
always be there.

What I tell people is that Babbage theorized the computational device and
Lady Ada extended the theorized to general programmability  (to play music
I believe) but it was never built and she and Babbage argued a bit about
it.   The Loom folks demonstrated that the idea programmability was
possible.   Zuse put the two idea together and reduce it practice.

But .. until we also include a conditional branch the ability to do self
modify code we don't really have the machine with think of as the automatic
programmable computer.

Check out:
http://page.mi.fu-berlin.de/rojas/1993/Who_invented_the_computer.pdf its a
fun read.

There is a nice table in it:

Machine             Memory & CPU Separated           Conditional Branching
       Soft or Hard Programming      Support Self Modify    Indirect
Addressing
Babbage                   yes
    yes                                    soft
              proposed                      no
Zuse                          yes
         no                                    soft
                        no                           no
Atanasoff                   yes
       no                                    hard
                     no                          no
Aiken Mark1              no
    no                                    soft
                  no                           no
ENIAC                       no
       partial                              hard
                   no                          no
Manchester               yes
  yes                                    soft
                   yes                        no
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://minnie.tuhs.org/pipermail/tuhs/attachments/20180512/29879436/attachment.html>

[TUHS] The birth of the Z3

[Dave Horsfall]

Way back on this day in 1941, Conrad Zuse unveiled the Z3; it was the 
first programmable automatic computer as we know it (Colossus 1 was not 
general-purpose).  The last news I heard about the Z3 was that she was 
destroyed in an air-raid...

This pretty much started computing, as we know it.

-- Dave