RL02 version of UNIX6?

Josh Dersch derschjo at gmail.com
Wed Feb 1 15:01:28 CST 2017

On Wed, Feb 1, 2017 at 12:56 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu>

>     > From: William Degnan
>     > 64K.
> That's 64KB, right? DEC used to talk of PDP-11 memory in words, back in the
> day, so it's never quite clear unless the 'B' or 'W' is specified.
> Anyway, 64KB out to be enough to run most things. I have't looked to see
> how
> big a system with just RL and DL drivers, and a minimum number of disk
> buffers
> (that's probably the easiest way to get the size down almost as far as it
> will
> go) is, but it's probably in the region of 30-35KB (20KB text, and 10-15 KB
> data). That leaves plenty for user processes (not max sized, of course).
>     > I'd like to get another M7891, mine is only 1/2 populated.
> Oh, so that must have been 64KW - 128KB. That will give you plenty of room
> for
> a decent-sized kernel, and user processes. Wonder why it won't boot, then?
> Anyway, those are pretty rare. I have a couple of spare M7847's; they're
> only
> 32KB, but they'd help. You've got a couple of spare hex MUD slots now in
> the
> DD11-C, right? Speaking of which, where is the M7891 plugged in? It
> couldn't
> go in the DD11-B, or in the CPU backplane?
>     > typing anything kills the CPU and I have to restart the system..
> Sorry, need exact details: after the '!' prompt, anything you type kills
> the system on the first character? Or only "rlunix<CR>" does? How about
> "foobar<CR>"? I'd have to look at the bootstrap source, but I think
> typing a non-existing file name should take you back to the top-level
> prompt.
>         Noel

I just tried booting this in simh (as an 11/40 with 64k) and the cpu halts
after entering "rlunix<CR>"  (Entering an invalid name just returns you to
the "!" prompt).  Configuring simh as an 11/45 allows it to boot.

Looks like you'll need to rebuild the kernel with support for the 11/40.

- Josh

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