Linux-Development-Sys Digest #107, Volume #7 Wed, 25 Aug 99 18:14:10 EDT
Contents:
Re: Bypass Login ("Michael Halbig")
Re: is there a package for linux(rh6.0) to allow viewing of powerpoint(.ppt)
documents ? (David T. Blake)
Re: Cingle User - Kiosk Mode (Chris F Clark)
knfsd compile error (Klaus Schneider)
Re: Linux on embedded systems: question on memory footprint (Emile van bergen)
Re: Bypass Login (Eric Hegstrom)
Re: What are difference between Monolithic kernel architecture & Microkernel
architecture (EugeneK)
KERNELD (Fernando Ortega Bellosta)
Linking in arbitrary binary data (Jason Neudorf)
Re: Jesus: the ultimate OS ("Stuart Fox")
Re: Jesus: the ultimate OS (FS)
Re: Bypass Login (Eric Hegstrom)
Re: PROPOSAL: A secure, simple NIS replacement (Jonathan Abbey)
Re: C++ templates: More than Turing Complete? ([EMAIL PROTECTED])
Re: affs freezes kernel 2.2.11 ("BennyBoy")
Re: C++ templates: More than Turing Complete? (Ulrich Weigand)
----------------------------------------------------------------------------
From: "Michael Halbig" <[EMAIL PROTECTED]>
Crossposted-To: comp.os.linux.development.apps,comp.os.linux.misc,de.comp.os.linux
Subject: Re: Bypass Login
Date: Wed, 25 Aug 1999 17:27:32 +0200
Modifiziere die /etc/inittab:
Mach Dir dort Deinen eigenen Runlevel (z.B. 8) und starte in mit diesem
Runlevel Deine Applikation. Du kannst Dann auch genau entscheiden was Du
alles starten willst.(in deinem Fall startest Du in diesem Runlevel keine 6
mingetty `s )
ciao Michael
------------------------------
From: [EMAIL PROTECTED] (David T. Blake)
Subject: Re: is there a package for linux(rh6.0) to allow viewing of powerpoint(.ppt)
documents ?
Date: 25 Aug 1999 14:11:24 GMT
Reply-To: [EMAIL PROTECTED]
dan <[EMAIL PROTECTED]> wrote:
> does linux have a package for viewing powerpoint files (.ppt) i
> would HATE to have to load windows on my system to be able to
> view these files
If you would HATE it so much maybe you should have thought of
that before using M$Office.
Try StarOffice, it has a Powerpoint equivalent. I know it has
decent import filters for M$Word and M$Excel, so it may
do Powerpoint too.
--
Dave Blake
[EMAIL PROTECTED]
------------------------------
From: Chris F Clark <[EMAIL PROTECTED]>
Subject: Re: Cingle User - Kiosk Mode
Date: Wed, 25 Aug 1999 15:47:23 GMT
> You shouldn't use single user mode for a kiosk. You should alter your
> boot scripts to run
>
> su --login kioskuser
>
> instead of login after you've added a special user called 'kioskuser'.
The term "kiosk" is unknown to me in this context, but this posting
sounds like a solution to a problem that I would like fixed.
I would like my home system to be more of a "single user system". In
particular, when it boots I would like the system to automatically log
the console in as me (my account) rather than putting up a welcome
screen and having me select my account and then entering the password.
>From this posting, I gather that one of the boot files (perhaps an
/etc/rc.d file) runs "login" for the console and that if I replace
that with an "su me"--it will log "me" in instead of bringing up the
welcome screen.
Now, I could use some help in some of the details. I am running rh6.
Which boot file contains the magic "login" command that I will
replace?
My account is passworded. Will I have to do something with
/etc/pam/login (or /etc/pam/su) to prevent it from asking for a
password on the console when this process runs at boot time? The
whole point of this is to make it "convenient" for me, so that when I
sit down at the console I never have to "log in". I have the system
(and console) physically secure (i.e. in my locked house) thus I am
willing to trust that console users are never malicious.
Will I open a security hole in doing this? Is there a way to make
this account secure so that I can allow telenets into my machine? (I
connect my home machine via ppp to a corporate lan that is connected
(via a firewall) to the internet, soon I will have a cable modem
connection directly to the internet. I like to access my work
machines from home and home machines from work, but I realize that I
have to protect myself from crackers.)
Is there a way that I can have the system bring up the normal
login/welcome screen if I log out? (Sometimes, I might want to allow
another user (e.g. my wife) to use the console and I want them using
their own account and have their own window manager etc.)
-Chris
*****************************************************************************
Chris Clark Internet : [EMAIL PROTECTED]
Compiler Resources, Inc. CompuServe : 74252,1375
3 Proctor Street voice : (508) 435-5016
Hopkinton, MA 01748 USA fax : (508) 435-4847 (24 hours)
==============================================================================
Web Site in Progress: Web Site : http://world.std.com/~compres
==============================================================================
------------------------------
From: [EMAIL PROTECTED] (Klaus Schneider)
Subject: knfsd compile error
Date: 25 Aug 1999 17:28:55 GMT
Hi,
trying to compile knfsd 1.4.4 I get an error I can�t fix:
Making all in nfs
gcc -g -O2 -D_GNU_SOURCE -I../../support/include -Wall -pipe -c nfsctl.c -o
nfsctl.o
nfsctl.c: In function `nfsctl':
nfsctl.c:23: `__NR_nfsservctl' undeclared (first use in this function)
nfsctl.c:23: (Each undeclared identifier is reported only once
nfsctl.c:23: for each function it appears in.)
make[2]: *** [nfsctl.o] Error 1
make[1]: *** [all] Error 2
make: *** [all] Error 2
I think, __NR_nfsservctl (or __NR_nfsctl) should be defined
somewhere in /usr/include/linux/ but it isn`t (I`ve looked
for it using grep).
What is wrong here? I am using kernel 2.2.11 on an i586 machine.
Thanks for your help,
Klaus
------------------------------
From: Emile van bergen <[EMAIL PROTECTED]>
Crossposted-To: comp.os.linux.development.apps,comp.os.linux.help
Subject: Re: Linux on embedded systems: question on memory footprint
Date: Wed, 25 Aug 1999 17:55:19 +0000
On Wed, 25 Aug 1999, Steve Houseman wrote:
[SNIP]
>Playing around (a dangerous thing) with linking shows that when
>a (shared) library is linked and something is needed , then the whole
>shebang is loaded not just the fn you want , so I *believe* that
>the RSS reported by top is just the data segment of the prog
>with all the lib vars in it (libc is much larger than that) ??
>I could be wrong on this and would welcome comments and urls for this.
The whole shebang is _mmap()'ed_, not allocated in real memory and
loaded from disk. So as soon as you use a function whose page(s) are not
in core, its page(s) are read from disk, but only then. If your memory
gets exhausted, the RO pages are simply discarded (why swap them, if the
source of the information is already on disk?), and the dirty RW pages
are swapped out.
The RSS is the size of the image which is in core. So it may indeed well
be much less than the whole libc. For example, if you'd just call
printf(), it would show only the pages used by printf() code and
data.
>So if you have a small app not linked with other code
>and which only used a small seg of lib c , then could
>extract the bits from the libc source and compile them,
>and link them as above .
Why? Remember, Linux is a virtual memory system. It won't help you all
that much, except the overhead in case the used code is only 10 bytes,
then you'd waste 4096-10 bytes of physical memory.
[SNIP]
>Just experimented with an extended sleep , and run up a few
>netscapes so am using 20Mb of 100Mb swap partition and left
>running for a while, but the RSS size of zz6 does not come down
>and I dont believe that it is using actively 192 kb ...
>on a real unix <ducks> this would have disappeared ie would
>have been paged out and the RSS value would have gone
>almost to zero ... so linux does not seem to do its
>paging correctly (or at least the same as other unices ... pity).
A real bad 'real' unix that would be, one that pages out an executable
that's ready to run (zz6 contains a busy wait loop, doesn't it?).
--
M.vr.gr. / Best regards,
Emile van Bergen (e-mail address: [EMAIL PROTECTED])
This e-mail message is 100% electronically degradeable and produced
on a GNU/Linux system.
~
~
:wq
------------------------------
From: Eric Hegstrom <[EMAIL PROTECTED]>
Crossposted-To:
comp.os.linux.development.apps,comp.os.linux.misc,de.comp.os.linux,jaring.os.linux
Subject: Re: Bypass Login
Date: Wed, 25 Aug 1999 09:17:21 -0700
or you can use the a command like the following in your boot script
(inittab of the proper rc file):
su --login UserName
where Username is the account you want to start. Make sure to NOT start
mingetty on that tty.
Here is one simple way. (I actual create a new run level myself)
In /etc/inittab do the following:
set the default runlevel to 5
id:5:initdefault:
remove level 5 from the line that starts mingetty on tty1
1:234:respawn:/sbin/mingetty tty1
change the line to run xdm in level 5 to run the su command
x:5:respawn:/su --login UserName
where UserName is the user whose account you want to jump into. You can
then put the startup stuff in the .profile or .bashrc file in the
~UserName directory.
I would like to thank Tristen Wibberley for pointing out the su --login
command to me yesterday. Saved lots of work.
Cheers,
Eric
==========
Bartosz Klimek wrote:
>
> stan168 wrote:
> > Is there anyway to bypass the login session and straight away run my
> > application after linux started? Also is there anyway to start my app
> > without starting the window manager after the X Windows started?
> >
> > My situation is just to start only my application for the user to use and
> > prevent the user to mess around with others after booting the system.
>
> It's all possible. This is what we like about Linux :)
>
> Have a look at /etc/inittab. You can modify it so that it runs your
> script after system starts up. In my system the last line of the file
> is:
>
> x:5:respawn:/etc/X11/prefdm -nodaemon
>
> You could change it to (e.g.):
>
> x:5:respawn:/etc/X11/my_script
>
> /etc/X11/my_script would start X11 and then your application.
>
> However, I think it would nice to modify the X11 startup scripts so that
> your app is started instead of a window manager.
>
> This is just an idea. Maybe there is some more elegant solution.
>
> Good luck,
>
> --
> Bartosz Klimek
> mailto:[EMAIL PROTECTED]
--
Eric Hegstrom .~.
Senior Software Engineer /V\
Sonoran Scanners, Inc. // \\ L I N U X
[EMAIL PROTECTED] /( )\ >don't fear the penguin<
520-617-0072 x402 ^^-^^
------------------------------
From: [EMAIL PROTECTED] (EugeneK)
Subject: Re: What are difference between Monolithic kernel architecture & Microkernel
architecture
Date: Wed, 25 Aug 1999 16:47:12 GMT
On Wed, 25 Aug 1999 16:33:40 +0800, "Richard Lo" <[EMAIL PROTECTED]>
wrote:
>Hi
>I am interested in the Linux kernel. I knew the Linux kernel use monolithic
>kernel architecture. Anyway, I have no idea about monolithic kernel
>architecture and what differ from microkernel architecture.
>Best regards,
>Richard
>
>
The difference are in what kernel does. Monolitic kernel always sits
in the memory with its different parts providing different services
(memory management, file system, etc.). Its disadvantage - modern
OSes are quite complex, so the kernel itself becomes a very complex
peice of software (it took a lot of people around the world to develop
Linux). As a result, it might be argued it is impossible to create
using "Cathedral" development form.
Microkernel is a very small piece of code that does only one thing: it
knows when and where to find and load the module whose services
are needed at the moment. All services are done by the modules.
Its disadvantage - it is slower then monolitic kernel (I am going to
get flamed here, this is one of the subjects for "holy war''). Another
thing - I suspect it is a nightmare to check all possible interaction
between the modules - witness Hurd - it is still not usable at this
point.
Hope it answers your question.
Eugene.
------------------------------
From: Fernando Ortega Bellosta <[EMAIL PROTECTED]>
Subject: KERNELD
Date: Tue, 24 Aug 1999 17:57:19 +0200
HOw can I do to get one of my modules started at boot time.
Where do I have to insert , somethig like "request_module(my_module);"
Thanks a lot, Fernando Ortega
------------------------------
From: [EMAIL PROTECTED] (Jason Neudorf)
Subject: Linking in arbitrary binary data
Date: 25 Aug 1999 15:01:20 -0400
A while back, I asked about including arbitrary binary data in a file, ie
putting a ".jpg" for example inside the object code itself, like a PalmPilot
or Mac resource. This might be useful if we need to push some code into some
dsp or video card, or print the linux penguin at boot time. Rather than
do icky transformations on an octal dump of the file in question, something
simple can be used.
I had one perl script that generated the data automatically, but NASM has
a nice feature that I thought was nicer. You can write something like this:
============================
SECTION .data
global logo:data (logo.end - foo)
logo: incbin "/usr/src/linux/Documentation/logo.gif"
.end
============================
Then, you can use "extern char* logo;" in a "c" program, and use "logo" as
a pointer to the data of that ".gif".
It's quite nice I think. Perhaps this will be useful to someone.
Why don't people do things like this more often, at least for default
resources?
------------------------------
From: "Stuart Fox" <[EMAIL PROTECTED]>
Crossposted-To: alt.os.linux,comp.os.linux.advocacy,comp.os.misc,comp.unix.advocacy
Subject: Re: Jesus: the ultimate OS
Date: Thu, 26 Aug 1999 08:05:01 +1200
Christopher R. Thompson <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> Paul E. Lehmann wrote:
> >
> > Hmmm,
> >
> > Ok, Lets see. Jesus was one of many so called "Healers and Messiahs" of
his
> > day"
>
> Have YOU NOT seen miracles and healing? Is that his fault, or your own?
There is plenty of evidence that so called miracles of Jesus were nothing
more than breaking societies norms of the time.
>
> > If you believe that such an individual actually existed then it can be
said
>
> I do. You hear his name every day many times a day. How can it possibly
> be a figment of so many peoples imaginations. I think your mind is
> playing tricks on you!
He almost certainly existed, and there were almost certainly two of him
(Jesus and his brother James)
>
> > been gay, practiced the arts of a magician and had extreme contempt for
non
>
> Not possible and totally inaccurate.
> Christians are not allowed to look to magicians, scientists,
> astrologers, soothsayers, etc, for any kind of direction or indirection
> but to GOD only.
There is also plenty of evidence that the whole religion is based on
Egyptian religion. But you knew that because you've researched this
thoroughly?
Have a look at all the books that didn't make it into the Bible because they
didn't toe the party line.
------------------------------
From: FS <[EMAIL PROTECTED]>
Crossposted-To: alt.os.linux,comp.os.linux.advocacy,comp.os.misc,comp.unix.advocacy
Subject: Re: Jesus: the ultimate OS
Date: Wed, 25 Aug 1999 20:32:01 GMT
There are many more evil people who will choose the OS Gates than will choose
the OS Jesus.
"Christopher R. Thompson" wrote:
> Selious wrote:
> >
> > > I'm going to name my OS "Jesus". It will coded primarily to destroy all
> > > "EVIL" objects os's and computers. Only the objects that "LOVE" Jesus
> > > will survive and communicate with "Jesus".
> >
> > OK, my OS, named Gates, is going to represent the evil in society...
> >
> > Let's see who wins, hehehe
> >
>
> Truly sir: Only those who love Jesus will live to see the Glory.
>
> TfJC.Com: up 67 days, 9:14,
>
> > --
> > pii350.ntdom: up 24 days, 22:55,
> > linux.ntdom: up 118 days, 22:33,
> > nw411.ntdom 112 days, 14:31
> > nwtest.ntdom 123 days, 20:57
> > alpha.ntdom: 1:06am up 59 days,
> > linux4.ntdom: up 105 days, 58
> > freebsd.ntdom: up 19 days, 3:03,
------------------------------
From: Eric Hegstrom <[EMAIL PROTECTED]>
Crossposted-To:
comp.os.linux.development.apps,comp.os.linux.misc,de.comp.os.linux,jaring.os.linux
Subject: Re: Bypass Login
Date: Wed, 25 Aug 1999 11:02:44 -0700
The only problem I am running into with this method is that my X client
claims "Authentication fails" when I try to connect to it when my
account is started using "su --login userName". If I go through the
normal mingetty login everything is OK. Does anyone know how to address
this. Should I be using the .Xauthority file created when I did the
sucessful xinit from the mingetty login. I have looked at the Xsecurity
manpage bu t obviously have not analyzed it in depth.
Any suggestions would be very appreciated.
Cheers,
Eric
Eric Hegstrom wrote:
>
> or you can use the a command like the following in your boot script
> (inittab of the proper rc file):
>
> su --login UserName
>
> where Username is the account you want to start. Make sure to NOT start
> mingetty on that tty.
>
> Here is one simple way. (I actual create a new run level myself)
> In /etc/inittab do the following:
> set the default runlevel to 5
> id:5:initdefault:
>
> remove level 5 from the line that starts mingetty on tty1
> 1:234:respawn:/sbin/mingetty tty1
>
> change the line to run xdm in level 5 to run the su command
> x:5:respawn:/su --login UserName
>
> where UserName is the user whose account you want to jump into. You can
> then put the startup stuff in the .profile or .bashrc file in the
> ~UserName directory.
>
> I would like to thank Tristen Wibberley for pointing out the su --login
> command to me yesterday. Saved lots of work.
>
> Cheers,
> Eric
> ----------
>
> Bartosz Klimek wrote:
> >
> > stan168 wrote:
> > > Is there anyway to bypass the login session and straight away run my
> > > application after linux started? Also is there anyway to start my app
> > > without starting the window manager after the X Windows started?
> > >
> > > My situation is just to start only my application for the user to use and
> > > prevent the user to mess around with others after booting the system.
> >
> > It's all possible. This is what we like about Linux :)
> >
> > Have a look at /etc/inittab. You can modify it so that it runs your
> > script after system starts up. In my system the last line of the file
> > is:
> >
> > x:5:respawn:/etc/X11/prefdm -nodaemon
> >
> > You could change it to (e.g.):
> >
> > x:5:respawn:/etc/X11/my_script
> >
> > /etc/X11/my_script would start X11 and then your application.
> >
> > However, I think it would nice to modify the X11 startup scripts so that
> > your app is started instead of a window manager.
> >
> > This is just an idea. Maybe there is some more elegant solution.
> >
> > Good luck,
> >
> > --
> > Bartosz Klimek
> > mailto:[EMAIL PROTECTED]
>
> --
> Eric Hegstrom .~.
> Senior Software Engineer /V\
> Sonoran Scanners, Inc. // \\ L I N U X
> [EMAIL PROTECTED] /( )\ >don't fear the penguin<
> 520-617-0072 x402 ^^-^^
--
Eric Hegstrom .~.
Senior Software Engineer /V\
Sonoran Scanners, Inc. // \\ L I N U X
[EMAIL PROTECTED] /( )\ >don't fear the penguin<
520-617-0072 x402 ^^-^^
------------------------------
From: [EMAIL PROTECTED] (Jonathan Abbey)
Crossposted-To: comp.security.unix
Subject: Re: PROPOSAL: A secure, simple NIS replacement
Date: 25 Aug 1999 12:52:58 -0500
In article <7q0vdj$sh5$[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> wrote:
|
| [EMAIL PROTECTED] (Jonathan Abbey) wrote:
|
| > There have been several NIS-type ideas implemented... NIS, NIS+,
| > Kerberos/Hesiod, and the netinfo stuff that NeXT used. We still use
| > NIS for almost everything because of the ubiquity of it, but a lot of
| > people are moving to LDAP for this sort of thing.
|
| NIS, NIS+, Kerberos/Hessiod and LDAP all have the same problem. I
| already have a user list on my system in some fashion. Its either in the
| passwd file, or broken out (e.g. shadow passwords), and I don't WANT to
| maintian another database.
NIS can run off of your normal /etc/passwd file if you're not using
shadow passwords.. if you are using shadow passwords, you can have
your NIS build scripts automatically merge the two at update time to
achieve the same effect.
| Don't know about netinfo. My idea was simply this: distribute
| /etc/passwd information on UNIX systems without compromising security
| (the way NIS does). The very complex ideas cited by others miss this
| point. I don't want something that can slice my vegetables, I want a
| distributed /etc/passwd in as small an amount of code as possible.
It sounds like you want something not much more complex than an NIS
over SSL, then.
I think many sites that need to avoid NIS for security reasons wind up
using something like SSH and/or cfengine to set up their own
/etc/passwd replication schemes.
It seems like it would be a bit of a waste to develop a new network
directory service for the sole purpose of avoiding having to maintain
a proper network information database. It sounds like you could
achieve a lot of what you want by simply modifying the server from the
Linux NISkit distribution so that it will consult a list of acceptable
hosts to provide information to. I have done mods to the NIS code
before, it's not that bad..
| -AJS
--
===============================================================================
Jonathan Abbey [EMAIL PROTECTED]
Applied Research Laboratories The University of Texas at Austin
Ganymede, a free NIS/DNS management system http://www.arlut.utexas.edu/gash2
------------------------------
From: [EMAIL PROTECTED]
Crossposted-To: comp.os.linux.development.apps,comp.os.linux.networking
Subject: Re: C++ templates: More than Turing Complete?
Date: Wed, 25 Aug 1999 20:41:34 GMT
In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] wrote:
> In article <7pu50r$[EMAIL PROTECTED]>
> [EMAIL PROTECTED] "Ulrich Weigand" writes:
> > Eh? C++ is of course Turing complete, but so is every assembly
language
> > to which it might be compiled ... I don't know of *any* programming
> > language in real use that is *not* Turing complete, b.t.w.;
>
> How about the C preprocessor?
>
> > there isn't
> > really much that is necessary to achieve Turing completeness (if you
> > have something like elementary arithmetic, assignment, and
conditional jump,
> > that's already enough ...).
^^^^^^ I don't agree with the above. In all
Turing-complete models, e.g. a Turing Machine,
a Unlimited Register Machine, one crucial component
is potential infinity or unboundedness. E.g. a
Turing machine at any given moment in a computation
has a finite # of cells on the tape, but there
is no upper bound to how many we can add to the
tape if necessary. Similarly, with the Unlimited
Register Machine, a particular program only uses
a finite # of registers of the countably infinite
# of machine regs, BUT the contents of each
register is a unbounded natural #!!!! On a "real world"
machine, the contents of a memory cell or a register are
bounded!!! I.e. real machines are finite, i.e. cannot
handle unboundedness. Or to put anyway, we can have overflow.
Hence, I would say real machines are Turing-bounded!!
Regards,
Bill Halchin
Sorry, I saw later post where it said this should be in other
group but I wanted to correct what I see as a misunderstanding
of Turing complete.
> >
>
> --
> Phil [EMAIL PROTECTED]
>
>
Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.
------------------------------
From: "BennyBoy" <[EMAIL PROTECTED]>
Subject: Re: affs freezes kernel 2.2.11
Date: Wed, 25 Aug 1999 22:13:51 +0100
Hi root :)
I too have the same problem with 2.2.11 (well 2.2.11-ac3 to be precise :)
I have a 2.2.5-15 kernel installed also and AFFS insmod'd -f (from the
2.2.11-ac3)
install loads without problems.
However, I cannot for the life of me get an amiga disk to mount.
I'm trying to mount a secondary slave IDE Amiga HD but get the following:
AFFS: Could not determine device size
mount: wrong fs type, bad option, bad superblock on /dev/hdd?
etc...
I've tried hdd1 to 8 :) but still no joy.
Anyone got any ideas?
Benny
root <[EMAIL PROTECTED]> wrote in message
news:9Ptu3.1199$[EMAIL PROTECTED]...
> Has anyone had any luck mounting an Amiga ffs disk with any Linux
> kernel? While I was picking goodies in the 2.2.11 kernel to enable, I
> decided to try adding affs, since I have a couple of Amiga formatted
> zip and syquest disks I'd like to access. Whether I use affs as a
> module or directly compiled in, as soon as I try
> mount -t affs /dev/sdb1 /mnt/azip
> I get something like
> RDSK sd(blur)(blur)(blur)
> with the first blur apparently being letters a through o, and the
> other blurs being digits 0-1 and 0-9. Since my Advansys SCSI
> controller works fine with VFAT, DOS, HFS, and the usual EXT2 disks,
> I can't imagine that this nonsense is. What's expecially vexing is
> that it locks the system up so hard, I have to hit the HW reset.
>
>
------------------------------
From: [EMAIL PROTECTED] (Ulrich Weigand)
Crossposted-To: comp.os.linux.development.apps,comp.os.linux.networking
Subject: Re: C++ templates: More than Turing Complete?
Date: 25 Aug 1999 23:36:06 +0200
[EMAIL PROTECTED] writes:
[ I wrote: ]
>> if you have something like elementary arithmetic, assignment, and
>> conditional jump, that's already enough ...
>I don't agree with the above. In all
>Turing-complete models, e.g. a Turing Machine,
>a Unlimited Register Machine, one crucial component
>is potential infinity or unboundedness.
[snip]
>Similarly, with the Unlimited
>Register Machine, a particular program only uses
>a finite # of registers of the countably infinite
># of machine regs, BUT the contents of each
>register is a unbounded natural #!!!!
Indeed, I should have been more precise: by 'elementary arithmetic'
I meant arithmetic on (arbitrary) natural numbers.
If everything is bounded, you just have a finite state automaton,
which certainly isn't Turing complete ;-)
>On a "real world"
>machine, the contents of a memory cell or a register are
>bounded!!! I.e. real machines are finite, i.e. cannot
>handle unboundedness. Or to put anyway, we can have overflow.
>Hence, I would say real machines are Turing-bounded!!
You do have a floppy drive in your machine, don't you ;-)
As long as you swap floppies (and buy new ones) as required
by the program, that's all the unboundedness you need ...
--
Ulrich Weigand,
IMMD 1, Universitaet Erlangen-Nuernberg,
Martensstr. 3, D-91058 Erlangen, Phone: +49 9131 85-7688
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