[TUHS] A Unix Code Walkthrough by Ken Thompson

[TUHS] A Unix Code Walkthrough by Ken Thompson

[Warren Toomey via TUHS]

Hi all, I've just received a set of MP3 recordings from Bob Kridle. He says:

    These are recordings of Ken Thompson doing a read through of one of
    an early UNIX kernel code listing with a group of grad students at
    UC Berkeley while he was a visiting prof. there.

The date is roughly 1975. I've put the recordings here along with his
e-mails about the recordings:

https://www.tuhs.org/Archive/Recordings/1975_Unix_Code_Walkthru/

I've only just listened to the first few minutes of each. The quality
is fine, but I might spend some time reducing the noise, bringing up
the quiet parts and removing a few clicks and pops.

If anybody else has more details of these recording, please let us know!

Cheers, Warren

[TUHS] Re: A Unix Code Walkthrough by Ken Thompson

[Warren Toomey via TUHS]

On Sun, Dec 29, 2024 at 07:40:15AM +1000, Warren Toomey via TUHS wrote:
> Hi all, I've just received a set of MP3 recordings from Bob Kridle. He says:
> 
>     These are recordings of Ken Thompson doing a read through of one of
>     an early UNIX kernel code listing with a group of grad students at
>     UC Berkeley while he was a visiting prof. there.
> 
> The date is roughly 1975. I've put the recordings here along with his
> e-mails about the recordings:
> 
> https://www.tuhs.org/Archive/Recordings/1975_Unix_Code_Walkthru/

Eric Allman has kindly supplied a scan of the source code that ken
provided for the walkthrough. I've added it to the above location.
It's interesting in that there are comments at the start of each
function - the existing 5th Edition code that we have does not
have these comments.

Cheers & thanks Eric!
	Warren

[TUHS] Re: A Unix Code Walkthrough by Ken Thompson

[Jonathan Gray]

On Mon, Jan 13, 2025 at 03:11:21PM +1000, Warren Toomey via TUHS wrote:
> On Sun, Dec 29, 2024 at 07:40:15AM +1000, Warren Toomey via TUHS wrote:
> > Hi all, I've just received a set of MP3 recordings from Bob Kridle. He says:
> > 
> >     These are recordings of Ken Thompson doing a read through of one of
> >     an early UNIX kernel code listing with a group of grad students at
> >     UC Berkeley while he was a visiting prof. there.
> > 
> > The date is roughly 1975. I've put the recordings here along with his
> > e-mails about the recordings:
> > 
> > https://www.tuhs.org/Archive/Recordings/1975_Unix_Code_Walkthru/
> 
> Eric Allman has kindly supplied a scan of the source code that ken
> provided for the walkthrough. I've added it to the above location.
> It's interesting in that there are comments at the start of each
> function - the existing 5th Edition code that we have does not
> have these comments.

With alloc.c the comments are there in v6 and the copyright line
removal matches the changes between v5 and v6.

The code appears to be somewhere between v6 and the "50 changes" tape
described by Mike O'Brien in:
Applications/Spencer_Tapes/unsw3.tar.gz
usr/sys/v6unix/changenotes

Some of the pages are dated 1976, and sysent[] on p 87 has post v6
system calls: access(), alarm(), pause().

Thanks to all involved for making this available.

[TUHS] Re: A Unix Code Walkthrough by Ken Thompson

[Jonathan Gray]

On Mon, Jan 13, 2025 at 05:23:11PM +1100, Jonathan Gray wrote:
> On Mon, Jan 13, 2025 at 03:11:21PM +1000, Warren Toomey via TUHS wrote:
> > On Sun, Dec 29, 2024 at 07:40:15AM +1000, Warren Toomey via TUHS wrote:
> > > Hi all, I've just received a set of MP3 recordings from Bob Kridle. He says:
> > > 
> > >     These are recordings of Ken Thompson doing a read through of one of
> > >     an early UNIX kernel code listing with a group of grad students at
> > >     UC Berkeley while he was a visiting prof. there.
> > > 
> > > The date is roughly 1975. I've put the recordings here along with his
> > > e-mails about the recordings:
> > > 
> > > https://www.tuhs.org/Archive/Recordings/1975_Unix_Code_Walkthru/
> > 
> > Eric Allman has kindly supplied a scan of the source code that ken
> > provided for the walkthrough. I've added it to the above location.
> > It's interesting in that there are comments at the start of each
> > function - the existing 5th Edition code that we have does not
> > have these comments.
> 
> With alloc.c the comments are there in v6 and the copyright line
> removal matches the changes between v5 and v6.
> 
> The code appears to be somewhere between v6 and the "50 changes" tape
> described by Mike O'Brien in:
> Applications/Spencer_Tapes/unsw3.tar.gz
> usr/sys/v6unix/changenotes

I've retyped the source code to make it easier to compare:
https://github.com/jonathangray/v6-allman

Some of the changes are in other v6-derived trees.  Some such as the
bootstrap and parity changes I couldn't find elsewhere.

[TUHS] Re: A Unix Code Walkthrough by Ken Thompson

[Jonathan Gray]

On Sun, Mar 16, 2025 at 05:26:19PM +1100, Jonathan Gray wrote:
> On Mon, Jan 13, 2025 at 05:23:11PM +1100, Jonathan Gray wrote:
> > On Mon, Jan 13, 2025 at 03:11:21PM +1000, Warren Toomey via TUHS wrote:
> > > On Sun, Dec 29, 2024 at 07:40:15AM +1000, Warren Toomey via TUHS wrote:
> > > > Hi all, I've just received a set of MP3 recordings from Bob Kridle. He says:
> > > > 
> > > >     These are recordings of Ken Thompson doing a read through of one of
> > > >     an early UNIX kernel code listing with a group of grad students at
> > > >     UC Berkeley while he was a visiting prof. there.
> > > > 
> > > > The date is roughly 1975. I've put the recordings here along with his
> > > > e-mails about the recordings:
> > > > 
> > > > https://www.tuhs.org/Archive/Recordings/1975_Unix_Code_Walkthru/
> > > 
> > > Eric Allman has kindly supplied a scan of the source code that ken
> > > provided for the walkthrough. I've added it to the above location.
> > > It's interesting in that there are comments at the start of each
> > > function - the existing 5th Edition code that we have does not
> > > have these comments.
> > 
> > With alloc.c the comments are there in v6 and the copyright line
> > removal matches the changes between v5 and v6.
> > 
> > The code appears to be somewhere between v6 and the "50 changes" tape
> > described by Mike O'Brien in:
> > Applications/Spencer_Tapes/unsw3.tar.gz
> > usr/sys/v6unix/changenotes
> 
> I've retyped the source code to make it easier to compare:
> https://github.com/jonathangray/v6-allman
> 
> Some of the changes are in other v6-derived trees.  Some such as the
> bootstrap and parity changes I couldn't find elsewhere.

A scheduler change from the Naval Postgraduate School, described by Ken as
"this is a fix from Monterey, and I think it's wrong".
Tape 1 (Cleaner) ~ 43:17

Mentioned in the November 1976 UNIX News
https://archive.org/details/unix_news_november-1976/page/n1/mode/2up
tuhs Documentation/Usenix/Early_Newsletters/197611-unix-news-n11.pdf

"Also available by separate request only is a new scheduler, which scans
the process table twice; the first pass throws out a process only if
that process alone will make room for the new process.  NPS claims 25%
improvement on a 48K machine, Ken Thompson thinks otherwise.  You will
have to judge for yourself."

And in February 1976, though the text in the scan is hard to read
https://archive.org/details/unix_news_feb-10-1976/page/n7/mode/2up
tuhs Documentation/Usenix/Early_Newsletters/19760210-unix-news-n3.pdf