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Linux 0.11 on Qemu.jpg
Linux 0.11 booted on Qemu
Type: Time-sharing
Creator: Linus Torvalds
Multitasking: Multitasking with paging/swap
Architecture: Originally 80386 now cross-platform.
Date Released: 1991

Linux is a computer operating system originally developed in the 1990s by a student Linus Torvalds. Today's Linux systems are split into various branches, developed over time by millions of volunteers, Debian, Ubuntu, RedHat, IBM as well as various commercial vendors.

Versions of relevance for hobbyists include ports to the Amiga, early Macs, a partial port to the VAX and a port to System/390 as well as various SGI and Sun Microsystems workstations and servers.

Linux gained in popularity because it was a 'fresh' implementation of UNIX, not incumbered by the AT&T vs BSDI/CSRG legal wars, and was not sidelined because of it. While the BSD world stalled during this lawsuit, Linux was able to thrive, and pick up users.

Minix days

The first public version of Linux (0.01) was originally bootstrapped from within Minix. The first versions required that you have a minix file system, and it booted from floppies ONLY. The only way to determine where the root filesystem was located, was to hex edit the boot floppy. Once Linux started to gain in popularity, it prompted one of the more famous flamewars between Linus Torvalds and Andy Tanenbaum.

The notes file from back then goes into the details.

Early distros

MCC Interim Linux, from Owen Le Blanc of the Manchester Computing Centre, was the first distro to be installable without the need of another operating system to partition, and format the hard disk. With the ease of installing from MCC, it gave rise to more comprehensive distros, namely SLS. MCC started out with Linux 0.12.

SLS, released some time in 1992. You can find some of the old SLS installs here. Qemu is capable of running some of them, keep in mind hard disks need to be small, and of course you'll need to force an ISA bus install (-M isa).

Debian and Slackware quickly superseded SLS, and continue to this day.

Early Versions

  • 0.00 The first "AAAABBBB" Kernel.
  • 0.01 The initial non working public version.
  • 0.02 The first 'working' public version, able to run bash & GCC.
  • 0.03 Linux apparently could build GCC under itself.
  • 0.10 Bug fixes, and greater stability.
  • 0.11 The last version to be cross compiled form Minix. Also first version with a floppy disk driver.
  • 0.12 Added PTY,shared libc/libm & 387 emulation support, along with paging (VM).
  • 0.95 Linux had made rapid progress at this point, and was optimistically approaching the 1.0 milestone.
  • 0.95a
  • 0.96a Added SCSI support
  • 0.96b
  • 0.96c Introduced UNIX domain sockets (still no TCP/IP) & the ext filesystem
  • 0.97 Adds MS-DOS filesystem.
  • 0.98 Introduction of TCP/IP mainly from Ross Biro
  • 0.99pl9 This was the basis for the Amiga m68k port.

Linux History

Linux History Note: The following text was written by Linus on July 31 1992. It is a collection of various artifacts from the period in which Linux first began to take shape.

This is just a sentimental journey into some of the first posts concerning linux, so you can happily press Control-D now if you actually thought you'd get anything technical.

From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) 
Newsgroups: comp.os.minix 
Subject: Gcc-1.40 and a posix-question 
Message-ID: <1991Jul3.100050.9886@klaava.Helsinki.FI> 
Date: 3 Jul 91 10:00:50 GMT 
Hello netlanders, 
Due to a project I'm working on (in minix), I'm interested in the posix 
standard definition. Could somebody please point me to a (preferably) 
machine-readable format of the latest posix rules? Ftp-sites would be 

The project was obviously linux, so by July 3rd I had started to think about actual user-level things: some of the device drivers were ready, and the harddisk actually worked. Not too much else.

As an aside for all using gcc on minix - [ deleted ]

Just a success-report on porting gcc-1.40 to minix using the 1.37 version made by Alan W Black & co.

Linus Torvalds 
PS. Could someone please try to finger me from overseas, as I've 
installed a "changing .plan" (made by your's truly), and I'm not certain 
it works from outside? It should report a new .plan every time. 

So I was clueless - had just learned about named pipes. Sue me. This part of the post got a lot more response than the actual POSIX query, but the query did lure out arl from the woodwork, and we mailed around for a bit, resulting in the Linux subdirectory on

Then, almost two months later, I actually had something working: I made sources for version 0.01 available on nic sometimes around this time. 0.01 sources weren't actually runnable: they were just a token gesture to arl who had probably started to despair about ever getting anything. This next post must have been from just a couple of weeks before that release.

From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) 
Newsgroups: comp.os.minix 
Subject: What would you like to see most in minix? 
Summary: small poll for my new operating system 
Message-ID: <1991Aug25.205708.9541@klaava.Helsinki.FI> 
Date: 25 Aug 91 20:57:08 GMT 
Organization: University of Helsinki 

Hello everybody out there using minix - 
I'm doing a (free) operating system (just a hobby, won't be big and 
professional like gnu) for 386(486) AT clones. This has been brewing 
since april, and is starting to get ready. I'd like any feedback on 
things people like/dislike in minix, as my OS resembles it somewhat 
(same physical layout of the file-system (due to practical reasons) 
among other things). 
I've currently ported bash(1.08) and gcc(1.40), and things seem to work. 
This implies that I'll get something practical within a few months, and 
I'd like to know what features most people would want. Any suggestions 
are welcome, but I won't promise I'll implement them :-) 
Linus ( 
PS. Yes - it's free of any minix code, and it has a multi-threaded fs. 
It is NOT protable (uses 386 task switching etc), and it probably never 
will support anything other than AT-harddisks, as that's all I have :-(. 

Judging from the post, 0.01 wasn't actually out yet, but it's close. I'd guess the first version went out in the middle of September -91. I got some responses to this (most by mail, which I haven't saved), and I even got a few mails asking to be beta-testers for linux. After that just a few general answers to quesions on the net:

From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) 
Newsgroups: comp.os.minix 
Subject: Re: What would you like to see most in minix? 
Summary: yes - it's nonportable 
Message-ID: <1991Aug26.110602.19446@klaava.Helsinki.FI> 
Date: 26 Aug 91 11:06:02 GMT 
Organization: University of Helsinki 
In article <> jkp@cs.HUT.FI 
(Jyrki Kuoppala) writes: 
>> [re: my post about my new OS] 
>Tell us more! Does it need a MMU? 
Yes, it needs a MMU (sorry everybody), and it specifically needs a 
386/486 MMU (see later). 
>>PS. Yes - it's free of any minix code, and it has a multi-threaded fs. 
>>>It is NOT protable (uses 386 task switching etc) 
>How much of it is in C? What difficulties will there be in porting? 
>Nobody will believe you about non-portability ;-), and I for one would 
>like to port it to my Amiga (Mach needs a MMU and Minix is not free). 
Simply, I'd say that porting is impossible. It's mostly in C, but most 
people wouldn't call what I write C. It uses every conceivable feature 
of the 386 I could find, as it was also a project to teach me about the 
386. As already mentioned, it uses a MMU, for both paging (not to disk 
yet) and segmentation. It's the segmentation that makes it REALLY 386 
dependent (every task has a 64Mb segment for code & data - max 64 tasks 
in 4Gb. Anybody who needs more than 64Mb/task - tough cookies). 
It also uses every feature of gcc I could find, specifically the __asm__ 
directive, so that I wouldn't need so much assembly language objects. 
Some of my "C"-files (specifically mm.c) are almost as much assembler as 
C. It would be "interesting" even to port it to another compiler (though 
why anybody would want to use anything other than gcc is a mystery). 

Note: linux has in fact gotten more portable with newer versions: there was a lot more assembly in the early versions. It has in fact been ported to other architectures by now.

Unlike minix, I also happen to LIKE interrupts, so interrupts are 
handled without trying to hide the reason behind them (I especially like 
my hard-disk-driver. Anybody else make interrupts drive a state- 
machine?). All in all it's a porters nightmare. 
>As for the features; well, pseudo ttys, BSD sockets, user-mode 
>filesystems (so I can say cat /dev/tcp/, 
>window size in the tty structure, system calls capable of supporting 
>POSIX.1. Oh, and bsd-style long file names. 
Most of these seem possible (the tty structure already has stubs for 
window size), except maybe for the user-mode filesystems. As to POSIX, 
I'd be delighted to have it, but posix wants money for their papers, so 
that's not currently an option. In any case these are things that won't 
be supported for some time yet (first I'll make it a simple minix- 
lookalike, keyword SIMPLE). 
Linus ( 
PS. To make things really clear - yes I can run gcc on it, and bash, and 
most of the gnu [bin/file]utilities, but it's not very debugged, and the 
library is really minimal. It doesn't even support floppy-disks yet. It 
won't be ready for distribution for a couple of months. Even then it 
probably won't be able to do much more than minix, and much less in some 
respects. It will be free though (probably under gnu-license or similar). 

Well, obviously something worked on my machine: I doubt I had yet gotten gcc to compile itself under linux (or I would have been too proud of it not to mention it). Still before any release-date.

Then, October 5th, I seem to have released 0.02. As I already mentioned, 0.01 didn't actually come with any binaries: it was just source code for people interested in what linux looked like. Note the lack of announcement for 0.01: I wasn't too proud of it, so I think I only sent a note to everybody who had shown interest.

From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) 
Newsgroups: comp.os.minix 
Subject: Free minix-like kernel sources for 386-AT 
Message-ID: <1991Oct5.054106.4647@klaava.Helsinki.FI> 
Date: 5 Oct 91 05:41:06 GMT 
Organization: University of Helsinki 
Do you pine for the nice days of minix-1.1, when men were men and wrote 
their own device drivers? Are you without a nice project and just dying 
to cut your teeth on a OS you can try to modify for your needs? Are you 
finding it frustrating when everything works on minix? No more all- 
nighters to get a nifty program working? Then this post might be just 
for you :-) 
As I mentioned a month(?) ago, I'm working on a free version of a 
minix-lookalike for AT-386 computers. It has finally reached the stage 
where it's even usable (though may not be depending on what you want), 
and I am willing to put out the sources for wider distribution. It is 
just version 0.02 (+1 (very small) patch already), but I've successfully 
run bash/gcc/gnu-make/gnu-sed/compress etc under it. 
Sources for this pet project of mine can be found at 
( in the directory /pub/OS/Linux. The directory also 
contains some README-file and a couple of binaries to work under linux 
(bash, update and gcc, what more can you ask for :-). Full kernel 
source is provided, as no minix code has been used. Library sources are 
only partially free, so that cannot be distributed currently. The 
system is able to compile "as-is" and has been known to work. Heh. 
Sources to the binaries (bash and gcc) can be found at the same place in 
ALERT! WARNING! NOTE! These sources still need minix-386 to be compiled 
(and gcc-1.40, possibly 1.37.1, haven't tested), and you need minix to 
set it up if you want to run it, so it is not yet a standalone system 
for those of you without minix. I'm working on it. You also need to be 
something of a hacker to set it up (?), so for those hoping for an 
alternative to minix-386, please ignore me. It is currently meant for 
hackers interested in operating systems and 386's with access to minix. 
The system needs an AT-compatible harddisk (IDE is fine) and EGA/VGA. If 
you are still interested, please ftp the README/RELNOTES, and/or mail me 
for additional info. 
I can (well, almost) hear you asking yourselves "why?". Hurd will be 
out in a year (or two, or next month, who knows), and I've already got 
minix. This is a program for hackers by a hacker. I've enjouyed doing 
it, and somebody might enjoy looking at it and even modifying it for 
their own needs. It is still small enough to understand, use and 
modify, and I'm looking forward to any comments you might have. 
I'm also interested in hearing from anybody who has written any of the 
utilities/library functions for minix. If your efforts are freely 
distributable (under copyright or even public domain), I'd like to hear 
from you, so I can add them to the system. I'm using Earl Chews estdio 
right now (thanks for a nice and working system Earl), and similar works 
will be very wellcome. Your (C)'s will of course be left intact. Drop me 
a line if you are willing to let me use your code. 
PS. to PHIL NELSON! I'm unable to get through to you, and keep getting 
"forward error - strawberry unknown domain" or something. 

Well, it doesn't sound like much of a system, does it? It did work, and some people even tried it out. There were several bad bugs (and there was no floppy-driver, no VM, no nothing), and 0.02 wasn't really very useable.

0.03 got released shortly thereafter (max 2-3 weeks was the time between releases even back then), and 0.03 was pretty useable. The next version was numbered 0.10, as things actually started to work pretty well. The next post gives some idea of what had happened in two months more...

From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) 
Newsgroups: comp.os.minix 
Subject: Re: Status of LINUX? 
Summary: Still in beta 
Message-ID: <1991Dec19.233545.8114@klaava.Helsinki.FI> 
Date: 19 Dec 91 23:35:45 GMT 
Organization: University of Helsinki 
In article <> (Miquel van 
Smoorenburg) writes: 
>Hello *, 
> I know some people are working on a FREE O/S for the 386/486, 
>under the name Linux. I checked now and then, to see what was 
>happening. However, for the time being I am without FTP access so I don't 
>know what is going on at the moment. Could someone please inform me about it? 
>It's maybe best to follow up to this article, as I think that there are 
>a lot of potential interested people reading this group. Note, that I don't 
>really *have* a >= 386, but I'm sure in time I will. 
Linux is still in beta (although available for brave souls by ftp), and 
has reached the version 0.11. It's still not as comprehensive as 
386-minix, but better in some respects. The "Linux info-sheet" should 
be posted here some day by the person that keeps that up to date. In 
the meantime, I'll give some small pointers. 
First the bad news: 
- Still no SCSI: people are working on that, but no date yet. 
Thus you need a AT-interface disk (I have one report that it 
works on an EISA 486 with a SCSI disk that emulates the 
AT-interface, but that's more of a fluke than anything else: 
ISA+AT-disk is currently the hardware setup) 

As you can see, 0.11 had already a small following. It wasn't much, but it did work.

  • still no init/login: you get into bash as root upon bootup.

That was still standard in the next release.

  • although I have a somewhat working VM (paging to disk), it's not ready yet. Thus linux needs at least 4M to be able to run the GNU binaries (especially gcc). It boots up in 2M, but you cannot compile.

I actually released a 0.11+VM version just before Christmas -91: I didn't need it myself, but people were trying to compile the kernel in 2MB and failing, so I had to implement it. The 0.11+VM version was available only to a small number of people that wanted to test it out: I'm still surprised it worked as well as it did.

  • minix still has a lot more users: better support.
  • it hasn't got years of testing by thousands of people, so there are probably quite a few bugs yet.

Then for the good things..

  • It's free (copyright by me, but freely distributable under a

very lenient copyright)

The early copyright was in fact much more restrictive than the GNU copyleft: I didn't allow any money at all to change hands due to linux. That changed with 0.12.

  • it's fun to hack on.
  • /real/ multithreading filesystem.
  • uses the 386-features. Thus locked into the 386/486 family, but

it makes things clearer when you don't have to cater to other chips.

  • a lot more... read my .plan.

I think it's better than minix, but I'm a bit prejudiced. It will never be the kind of professional OS that Hurd will be (in the next century or so :), but it's a nice learning tool (even more so than minix, IMHO), and it was/is fun working on it.

Linus ( 
---- my .plan -------------------------- 
Free UNIX for the 386 - coming 4QR 91 or 1QR 92. 
The current version of linux is 0.11 - it has most things a unix kernel 
needs, and will probably be released as 1.0 as soon as it gets a little 
more testing, and we can get a init/login going. Currently you get 
dumped into a shell as root upon bootup. 
Linux can be gotten by anonymous ftp from '' ( 
in the directory '/pub/OS/Linux'. The same directory also contains some 
binary files to run under Linux. Currently gcc, bash, update, uemacs, 
tar, make and fileutils. Several people have gotten a running system, 
but it's still a hackers kernel. 
Linux still requires a AT-compatible disk to be useful: people are 
working on a SCSI-driver, but I don't know when it will be ready. 
There are now a couple of other sites containing linux, as people have 
had difficulties with connecting to nic. The sites are: 
Tupac-Amaru.Informatik.RWTH-Aachen.DE ( 
directory /pub/msdos/replace ( 
directory /pub/linux 
There is also a mailing list set up ''. 
To join, mail a request to ''. 
It's no use mailing me: I have no actual contact with the mailing-list 
(other than being on it, naturally). 
Mail me for more info: 
Linus (torvalds@kruuna.Helsinki.FI) 
0.11 has these new things: 
- demand loading 
- code/data sharing between unrelated processes 
- much better floppy drivers (they actually work mostly) 
- bug-corrections 
- support for Hercules/MDA/CGA/EGA/VGA 
- the console also beeps (WoW! Wonder-kernel :-) 
- mkfs/fsck/fdisk 
- US/German/French/Finnish keyboards 
- settable line-speeds for com1/2 

As you can see: 0.11 was actually stand-alone: I wrote the first mkfs/fsck/fdisk programs for it, so that you didn't need minix any more to set it up. Also, serial lines had been hard-coded to 2400bps, as that was all I had.

Still lacking:

  • init/login
  • rename system call
  • named pipes
  • symbolic links

Well, they are all there now: init/login didn't quite make it to 0.12, and rename() was implemented as a patch somewhere between 0.12 and 0.95. Symlinks were in 0.95, but named pipes didn't make it until 0.96.

Note: The version number went directly from 0.12 to 0.95, as the follow-on to 0.12 was getting feature-full enough to deserve a number in the 0.90's

0.12 will probably be out in January (15th or so), and will have:

  • POSIX job control (by tytso)
  • VM (paging to disk)
  • Minor corrections

Actually, 0.12 was out January 5th, and contained major corrections. It was in fact a very stable kernel: it worked on a lot of new hardware, and there was no need for patches for a long time. 0.12 was also the kernel that "made it": that's when linux started to spread a lot faster. Earlier kernel releases were very much only for hackers: 0.12 actually worked quite well.

Note: The following document is a reply by Linus Torvalds, creator of Linux, in which he talks about his experiences in the early stages of Linux development

From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) 
Subject: Re: Writing an OS - questions !! 
Date: 5 May 92 07:58:17 GMT 
In article <> (V. Narayanan) writes: 

Hi folks, 
For quite some time this "novice" has been wondering as to how one goes about 
the task of writing an OS from "scratch". So here are some questions, and I 
would appreciate if you could take time to answer 'em. Well, I see someone 
else already answered, but I thought I'd take on the linux-specific parts. 
Just my personal experiences, and I don't know how normal those are. 

1) How would you typically debug the kernel during the development phase? 
Depends on both the machine and how far you have gotten on the kernel: 
on more simple systems it's generally easier to set up. Here's what I had 
to do on a 386 in protected mode. The worst part is starting off: after 
you have even a minimal system you can use printf etc, but moving to 
protected mode on a 386 isn't fun, especially if you at first don't know 
the architecture very well. It's distressingly easy to reboot the system 
at this stage: if the 386 notices something is wrong, it shuts down and 
reboots - you don't even get a chance to see what's wrong. Printf() isn't 
very useful - a reboot also clears the screen, and anyway, you have to 
have access to video-mem, which might fail if your segments are incorrect 
etc. Don't even think about debuggers: no debugger I know of can follow 
a 386 into protected mode. A 386 emulator might do the job, or some heavy 
hardware, but that isn't usually feasible. What I used was a simple 
killing-loop: I put in statements like 

jmp die 

at strategic places. If it locked up, you were ok, if it rebooted, you 
knew at least it happened before the die-loop. Alternatively, you might 
use the sound io ports for some sound-clues, but as I had no experience 
with PC hardware, I didn't even use that. I'm not saying this is the 
only way: I didn't start off to write a kernel, I just wanted to explore 
the 386 task-switching primitives etc, and that's how I started off 
(in about April-91). After you have a minimal system up and can use 
the screen for output, it gets a bit easier, but that's when you have to 
enable interrupts. Bang, instant reboot, and back to the old way. All 
in all, it took about 2 months for me to get all the 386 things pretty 
well sorted out so that I no longer had to count on avoiding rebooting 
at once, and having the basic things set up (paging, timer-interrupt 
and a simple task-switcher to test out the segments etc). 

2) Can you test the kernel functionality by running it as a process on a 
different OS? Wouldn't the OS(the development environment) generate 
exceptions in cases when the kernel (of the new OS) tries to modify 
'priviledged' registers? Yes, it's generally possible for some things, 
but eg device drivers usually have to be tested out on the bare machine. 
I used minix to develop linux, so I had no access to IO registers, 
interrupts etc. Under DOS it would have been possible to get access to 
all these, but then you don't have 32-bit mode. Intel isn't that 
great - it would probably have been much easier on a 68040 or similar. 
So after getting a simple task-switcher (it switched between two 
processes that printed AAAA... and BBBB... respectively by using the 
timer-interrupt - Gods I was proud over that), I still had to 
continue debugging basically by using printf. The first thing written 
was the keyboard driver: that's the reason it's still written completely 
in assembler (I didn't dare move to C yet - I was still debugging at 
about instruction-level). After that I wrote the serial drivers, and 
voila, I had a simple terminal program running (well, not that simple 
actually). It was still the same two processes (AAA..), but now they 
read and wrote to the console/serial lines instead. I had to reboot 
to get out of it all, but it was a simple kernel. After that is was plain 
sailing: hairy coding still, but I had some devices, and debugging was 
easier. I started using C at this stage, and it certainly speeds up 
developement. This is also when I start to get serious about my 
megalomaniac ideas to make "a better minix that minix". I was hoping 
I'd be able to recompile gcc under linux some day... The harddisk 
driver was more of the same: this time the problems with bad documentation 
started to crop up. The PC may be the most used architecture in the 
world right now, but that doesn't mean the docs are any better: in 
fact I haven't seen /any/ book even mentioning the weird 386-387 
coupling in an AT etc (Thanks Bruce). After that, a small 
filesystem, and voila, you have a minimal unix. Two months for basic 
setups, but then only slightly longer until I had a disk-driver 
(seriously buggy, but it happened to work on my machine) and a small 
filesystem. That was about when I made 0.01 available (late august-91? 
Something like that): it wasn't pretty, it had no floppy driver, and 
it couldn't do much anything. I don't think anybody ever compiled 
that version. But by then I was hooked, and didn't want to stop 
until I could chuck out minix. 3) Would new linkers and loaders 
have to be written before you get a basic 
kernel running? All versions up to about 0.11 were crosscompiled under 
minix386 - as were the user programs. I got bash and gcc eventually 
working under 0.02, and while a race-condition in the buffer-cache 
code prevented me from recompiling gcc with itself, I was able to 
tackle smaller compiles. 0.03 (October?) was able to recompile gcc 
under itself, and I think that's the first version that anybody 
else actually used. Still no floppies, but most of the basic things 
worked. Afetr 0.03 I decided that the next version was actually 
useable (it was, kind of, but boy is X under 0.96 more impressive), 
and I called the next version 0.10 (November?). It still had a 
rather serious bug in the buffer-cache handling code, but after patching 
that, it was pretty ok. 0.11 (December) had the first floppy driver, 
and was the point where I started doing linux developement under itself. 
Quite as well, as I trashed my minix386 partition by mistake when 
trying to autodial /dev/hd2. By that time others were actually using 
linux, and running out of memory. Especially sad was the fact that 
gcc wouldn't work on a 2MB machine, and although c386 was ported, it 
didn't do everything gcc did, and couldn't recompile the kernel. So I 
had to implement disk-paging: 0.12 came out in January (?) and had paging 
by me as well as job control by tytso (and other patches: pmacdona had 
started on VC's etc). It was the first release that started to 
have "non-essential" features, and being partly written by others. 
It was also the first release that actually did many things better 
than minix, and by now people started to really get interested. 
Then it was 0.95 in March, bugfixes in April, and soon 0.96. 
It's certainly been fun (and I trust will continue to be so) - reactions 
have been mostly very positive, and you do learn a lot doing this type 
of thing (on the other hand, your studies suffer in other respects :) 


See also

External links