Re: [TUHS] Upgrading from 11/40 to 11/45 in Unix v6

[jnc@mercury.lcs.mit.edu (Noel Chiappa)]

    > From: Will Senn

    > Thanks for not dismissing the thread as frivolity.

Hey, anyone wanting to do things with V6 I take seriously! :-)

    > I'm sure y'all have seen Mills's winning Best in Show IOCCC entry:
    > https://www.ioccc.org/2018/mills/hint.html

Yes, that was pretty awesome.


    > Fantastic, I'm prolly gonna try it.

OK; if you want to know what it's doing (somehow I figured you probably didn't
just want to simply follow the instructions :-) that is different from the /40
(it's quite different, and somewhat complicated), I just wrote this:

  http://gunkies.org/wiki/Unix_V6_kernel_memory_layout

to explain it a bit. Currently, one has to read the source to 'sysfix', and
also m45.s, to understand how the /45 version works; that new page is a little
crude still, but it hopefully explains the big picture.


    > If the instructions in Setting up are as good for the 45 as they are for
    > the 40, I should be able to bring one up relatively painlessly.

I just took a look at "Setting up UNIX - Sixth Edition", and it doesn't really
say much about the /45; it basically just says 'the /45 is wiered inside' and
'look at sys/run'. It is certainly true that that does cover all one needs to
bring V6 up on the /45, but... The coverage of what to do if your '45' has
hardware floating point is pretty complete, though.

    > What it sounds like is that Unix was transitioning from non-I/D land to
    > I/D land and maintaining a measure of backward compatibility

That's pretty accurate. One main advantage of the /45 is that it could have a
lot more disk buffers, but I'm not sure that makes much difference for
emulation. If you have some application that won't fit well in 64KB, that's
big, but that's a user-land difference, not the OS.


    > Is there a bootable tape of the MIT system extant?

Not yet, sorry. I do have a complete dump, but it i) includes all the users'
personal files, and ii) is not well organized. It's on my to-do list.

	 Noel