Some PDP-7 source code | Hacker News Reader

Some PDP-7 source code

minnie.tuhs.org

83 pointsrswier8 comments

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Warren Toomey from The Unix Heritage Society (TUHS) posts:

http://minnie.tuhs.org/pipermail/tuhs/2016-February/006622.h...

With the link:

http://www.tuhs.org/Archive/PDP-11/Distributions/research/Mc...

From the Readme:

  The structure of the kernel source code is very similar to that of the 1st Edition Unix scan at

  http://www.tuhs.org/Archive/PDP-11/Distributions/research/Dennis_v1/PreliminaryUnixImplementationDocument_Jun72.pdf

  Here is what I can glean from the files:

  01-s1.pdf     contains the kernel source divided into sections S1 to S9
  02-hw.pdf     has hardware details of the PDP-7
  03-scope.pdf  has information about the PDP-7 scope
  04-cas.pdf    seems to be a user-mode program that uses the PDP-7 scope
  05-1-4.pdf    user-mode programs: adm, ald, apr, as
  06-5-12.pdf   user-mode programs: bl, bc, bi, cat, check, chown, chmod, cp, chrm
  07-13-19.pdf  user-mode programs: db, dmabs, ds, dsksav, dskres, dskio, dsw, init
  08-rest.pdf   user-mode programs: ed. Also at the beginning some B code (?)

Looking at big pages of uncommented assembly like this really makes you understand why flowcharts and waterfall design were a thing.

The code appears to be some of the most ancient Unix Kernel Source Code yet found. This is previous to the PDP-11 1st Edition. Still, many of the familiar bits are there (ed, cat, etc..) A pretty historically significant chunk of code!

It's not untrue, but it's worth remembering that programming computers in assembly language was quite popular at that time, especially for systems software. Assembly has idioms that can be many lines long, and you tend to recognize them after you've programmed a system for long enough. 10 pages of uncommented, but idiomatic assembly code are more or less the equivalent of 2-3 pages of uncommented (but often idiomatic) C code, which can be fairly manageable.

Will this make its way to archive.org? I can't think of a better place for it.

I agree with you.

Unfortunately, I'm not sure archive.org has a clearly delineating way to make it easy to find source code. Many web pages embody some source code as well, but this isn't easy to find and decode.

And of course, there isn't really anything like git to manage the code.

I love seeing the handwritten notes...

in 01-s1.pdf: jms halt " will not happen

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