[HN Gopher] UNIX Fourth Edition
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       UNIX Fourth Edition
        
       Author : dcminter
       Score  : 105 points
       Date   : 2025-12-23 10:28 UTC (7 days ago)
        
 (HTM) web link (squoze.net)
 (TXT) w3m dump (squoze.net)
        
       | dcminter wrote:
       | This is the result of the tape from 1973 found at the University
       | of Utah being sent over to the Computer History Museum for
       | retrieval by bitsavers.org
       | 
       | Prior discussion: https://news.ycombinator.com/item?id=45840321
        
       | zatkin wrote:
       | Has anyone managed to extract out the C source files and upload
       | them into some browsable UI, e.g. GitHub or GitLab?
        
         | Someone wrote:
         | I think they're in the Unix history repo. Browsing there, it
         | may be https://github.com/dspinellis/unix-history-
         | repo/commits/Rese...
        
       | userbinator wrote:
       | It still amazes me that even with all this functionality, it runs
       | on a system with only 64k of RAM.
        
       | lproven wrote:
       | Just for what it's worth, I tried to explain the context and the
       | historical importance when I wrote about the original discovery
       | of the tape, and about the recovery:
       | 
       | https://www.theregister.com/2025/11/07/unix_fourth_edition_t...
       | 
       | https://www.theregister.com/2025/12/23/unix_v4_tape_successf...
        
       | aap_ wrote:
       | Hi, this is me. I'm still hacking on it but ran into some hard to
       | understand kernel bugs. once i mount more than the root
       | filesystem (say /usr/man) there are issues with inode
       | allocation/freeing. mixing and matching v4 and v5 stuff in
       | various ways can also lead to other interesting bugs but often an
       | allocated inode ends up on the freelist, and things break.
       | 
       | Otoh it's so much fun to hack and fiddle with the unix kernel :)
       | very zen
        
         | yjftsjthsd-h wrote:
         | > but ran into some hard to understand kernel bugs
         | 
         | Are the bugs in the original, or somehow artifacts of how we
         | got it? (Or, phrased differently: Were these bugs present at
         | the University of Utah in 1974, or are they "new"?)
        
           | aap_ wrote:
           | That's the puzzling thing. i find it hard to believe they
           | sent out an operating system that can't deal with multiple
           | file systems. yet i can't get them to work correctly. The
           | pre-v4 nsys kernel is another piece in the puzzle. it doesn't
           | have pipes implemented yet but aside from that (i put them
           | in) it also shows these "busy i" bugs, but even when running
           | on a single disk. Maybe there's more i'm doing wrong there
           | since it's running on the fs from the v4 tape. But that i'm
           | getting such similar bugs in different situations suggests
           | there is something wrong that i'm not seeing yet. gotta debug
           | more.
           | 
           | If it turns out to be a timing-related bug it may be that the
           | bug was much less obvious on real hardware.
        
             | is_taken wrote:
             | a) Do these inode issues also happen with the supplied (v4)
             | kernel? b) Do these inode issues also happen with a
             | rebuilded kernel which uses the original lib1 and lib2?
             | 
             | I once had strange effects on V6 if lib1 and/or lib2 were
             | rebuild by me.
             | 
             | Should be not hard to test.
        
       | 1vuio0pswjnm7 wrote:
       | "There's a video of the recovery here. It's only slightly over
       | five minutes long, but then, UNIX V4 wasn't very big yet: for
       | instance, the kernel was some 27 kB of code."
       | 
       | "It's very small: it contains around 55,000 lines of code, of
       | which about 25,000 lines are in C, with under 1,000 lines of
       | comments."
       | 
       | Yesterday, HN front page:
       | 
       | https://fzakaria.com/2025/12/28/huge-binaries
       | 
       | "Responses to my publication submissions often claimed such
       | problems did not exist; however, I had observed them during my
       | time within industry, such as at Google, but I couldn't cite it!
       | 
       | One problem that is only present at these mega-codebases is
       | massive binaries. What's the largest binary (ELF file) you've
       | ever seen? I had observed binaries beyond 25GiB, including debug
       | symbols."
       | 
       | It's funny that he could not publish about the laughably large
       | binary sizes at Google
       | 
       | Meanwhile employees at the company have often published papers
       | portraying the company's problems as interesting, perhaps as a
       | recruiting technique
        
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       (page generated 2025-12-30 23:01 UTC)