Linux Format forums

Re: Chepstow Junk Shop Find

nelz — Fri Oct 12, 2012 1:44 pm

Author: nelz

Posted: Fri Oct 12, 2012 1:44 pm

Nuke wrote:

More interesting is that a compiler can compile a better compiler than itself.

The first compile of the new one doesn't have to be better, it just has to work enough to compile itself. The gcc build process first builds the new gcc using the system compiler then builds it again using the compiler it just built, so it is truly self-compiled.

Nuke wrote:

However, serious question, how much of GNU is in Linux (sorry, GNU/Linux) today? BASH maybe. GCC is still widely used but does that make it part of it?

GCC is used to compile Linux, so there would not be the current Linux without it. Bash is not necessary, I don't use it, but coreutils is a GNU project. Try uninstalling that and seeing how far you can get

Re: Chepstow Junk Shop Find

Nuke — Fri Oct 12, 2012 1:37 pm

Author: Nuke

Posted: Fri Oct 12, 2012 1:37 pm

Nuke wrote:

How does a compiler compile itself?

nelz wrote:

That's easy. The tricky question is how does a compiler compile itself the first time?

That is what I meant. It is both a practical and philosophical question. I suppose that the first assembler was written in machine code and then a compiler written in assembly. More interesting is that a compiler can compile a better compiler than itself.

It is like lathes in the world of machine tools. You need a lathe to make a lathe, but the first ones must have been made by hand and very crude. But they progressively made better and better versions of themselves.

Nuke wrote:

... we would have been using GNU today, not Linux. He has had a chip on his shoulder about it ever since.

nelz wrote:

Aren't we using GNU/Linux? The chip is about people like you (and me) calling it Linux and ignoring the work done by the GNU devs.

I was not decrying the work of RMS and the GNU movement. They showed what could be done outside a corporate or (strictly speaking) academic environment. If they had not done that I would hardly have thought such a project possible. Some, like Darl McBride, still don't and I have known people who assume that Linux must be a rip-off from WINDOWS!

However, serious question, how much of GNU is in Linux (sorry, GNU/Linux) today? BASH maybe. GCC is still widely used but does that make it part of it? RMS considered Emacs part of it, but how many still use it? (The "Debian GNU/Linux Bible" http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0764576445.html of all books does not even have it in its index and recommends vim). Device drivers? I really do not know.

Re: Chepstow Junk Shop Find

Bazza — Fri Oct 12, 2012 1:35 pm

Author: Bazza

Posted: Fri Oct 12, 2012 1:35 pm

Hi nelz...

>> How does a compiler compile itself?

> That's easy. The tricky question is how does a compiler
> compile itself the first time?

Yup, indeed.

> The answer is it doesn't, a different compiler is user.

Yup, doing it longhand... OUCH!

Compilers are about as much use as a fart in a spacesuit
without an underlying OS, (a HAL being a minimum), that can
support it; and designing an OS is probably the single most
difficult thing of all.

I take my hat off to those who have successfully written an
OS of any level as an interpreter/compiler is, relatively, much
easier...

Re: Chepstow Junk Shop Find

nelz — Fri Oct 12, 2012 11:00 am

Author: nelz

Posted: Fri Oct 12, 2012 11:00 am

Nuke wrote:

The technical part of the manual is written with logical - almost painful - precision. He thinks of everything from first principles. Eg he has to explain what a key is :-

Quote:

"A complete key - where "key" is short for key sequence - is a sequence of keystrokes that are understood by Emacs as a unit, as a single command (possibly undefined). Most single characters constitute complete keys .."

What he is saying is that you can type a key like the letter "a", or you can invoke a control with a combination like "Ctrl-a".

Not exactly. In Emacs every key and key combination has a defined action. It so happens that the defined action for press a is to enter the character a, but this does not have to be so, you can redifine it to enter another character or perform a completely different action. The definition he gives is specific to how keys work in emacs.

Nuke wrote:

How does a compiler compile itself?

That's easy. The tricky question is how does a compiler compile itself the first time? The answer is it doesn't, a different compiler is used. Of course, some compilers may never be used to compile themselves, how about a Forth compiler written in C?

Nuke wrote:

Sad he never did finish that kernel, and never will, which is where the Linux kernel came in. It looks like RMS got embroiled with adding bells and whistles to Emacs when he should have got on with that kernel, and we would have been using GNU today, not Linux. He has had a chip on his shoulder about it ever since.

Aren't we using GNU/Linux? The chip is about people like you (and me) calling it Linux and ignoring the work done by the GNU devs. Of course that ignores that much of the GNU development is driven, and even financed, by Linux... and so the argument goes on.

Re: Chepstow Junk Shop Find

Nuke — Fri Oct 12, 2012 9:52 am

Author: Nuke

Posted: Fri Oct 12, 2012 9:52 am

Rhakios wrote:

And it has a picture of RMS riding a Gnu!!!

Then you should see the back cover too :-

A 1950's style US entrepreneur running away with our money. Unclear though if he is running to the bank with it or running away from the crusading RMS - although RMS is more in the garb of a saracen than a crusader. Note the 5.25" floppies

This was also before the day when Gates became the icon of greedy entrpreneurs :-

Re: Chepstow Junk Shop Find

Rhakios — Fri Oct 12, 2012 6:42 am

Author: Rhakios

Posted: Fri Oct 12, 2012 6:42 am

And it has a picture of RMS riding a Gnu!!!

Really, just spend your time looking at the cover, the contents can't possibly live up to that.

Chepstow Junk Shop Find

Nuke — Thu Oct 11, 2012 9:07 pm

Author: Nuke

Posted: Thu Oct 11, 2012 9:07 pm

When I saw this among the passe Jeffrey Archers and Danielle Steels, my first thought was that I was not interested in Emacs, but then I realised it was interesting both historically and in containing things such as the GNU Manifesto.

The technical part of the manual is written with logical - almost painful - precision. He thinks of everything from first principles. Eg he has to explain what a key is :-

Quote:

What he is saying is that you can type a key like the letter "a", or you can invoke a control with a combination like "Ctrl-a".

And :-

Quote:

"The space character is referred to as SPC, even though strictly speaking it is a graphic character whose graphic happens to be blank"

Priceless stuff! So I've been using a computer all these years and did not really know what the space bar was!

At the end of the book there is a section on mail-ordering Emacs. It is free, but you pay for the media, like $200 for Unix systems on 1600 bpi 9-track tape in Tar format.

In the GNU Manifesto he gives a report on the progress of the GNU Operating System. "So far", he writes, "we have an Emacs editor .. a debugger .. parser generator, a linker, and around 35 utilities. A shell .. is nearly complete. A .. C compiler has compiled itself and may be released this year. An initial kernel exists but many more features need to be added .. "

How does a compiler compile itself?

Sad he never did finish that kernel, and never will, which is where the Linux kernel came in. It looks like RMS got embroiled with adding bells and whistles to Emacs when he should have got on with that kernel, and we would have been using GNU today, not Linux. He has had a chip on his shoulder about it ever since.

I rate RMS as a modern-day genius, but a flawed one.