Two Stop Bits | It's not a given that a "Unix" on a PDP-10 would have taken off like the PDP-11 ...

larsbrinkhoff 1 day ago | parent

It's not a given that a "Unix" on a PDP-10 would have taken off like the PDP-11 version did. I believe the success of Unix was partially because it ran on an inexpensive and wildly popular mini.

Even as a PDP-10 fan, I have to admit that the PDP-10 was not exactly the wave of the future during the 1970s. It had a decent niche and a steadfast following, but sooner or later it would have disappeared in favor of 8-bit byte addressed computers.

KODust 1 day ago
Real alternative history territory here, but one path possible path is that it still have been attractive enough to port to the VAX, and we'd have ended up in roughly same place. Lots of handwaving and assumptions, of course.
I'm not sure Unix failing to take off would have been bad. It would certainly be a different world.
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- larsbrinkhoff 18 hours ago
  Some random thoughts. Writing a timesharing system for a computer with a 16-bit address space forced the Unix philosophy with many small single-purpose programs passing data between them. A timesharing system on a PDP-10 wouldn't have this constraint, and may well not have developed the Unix philosophy. Maybe that would have removed some of the appeal of "Unix-10".
  Second, the VAX grew from the PDP-11 as a 32-bit addressing extension. So porting from the PDP-11 to the VAX is rather natural and easy. In contrast, the PDP-10 is rather different from both the PDP-11 and VAX. Programs written in assembly language will not port over. If Bell labs would have developed a C language for the PDP-10, I wager it would have looked different and not have become popular in an 8-bit byte world.
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  - bmonkey325 9 hours ago
    Some forget that Unix started out on the pdp-7 which was 18-bit words so in some ways the architecture argument doesn’t really hold up. I think it’s more what machine were they could access.
    https://linfo.org/pdp-7.html#:~:text=The%20PDP-7%20was%20a%2....
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    - KODust 6 hours ago
      Yes, this is the thing -- it's clear that Ken Thompson valued simplicity, one reason being that he and a couple of other people could maintain the entire thing without a large support organization. Whether that would have survived the PDP-10, I'm not sure. But I suspect it would have have been recognizably Unix.
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- bmonkey325 23 hours ago
  Is this the parallel universe where Mac won and Windows faded into obscurity. Amiga took over gaming and PlayStation and XBox never happened ? .
  Also. Steve Jobs lives…..
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  - KODust 6 hours ago
    Dave Cutler stayed at DEC, shipped popular workstations built with PRISM chips, Microsoft and IBM kissed and made up and we're all using Windows derived from OS/2 w/Presentation Manager today.
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    - bmonkey325 57 minutes ago
      Put that way. In the hear and now, I realize we are in the darkest timeline.
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