[TUHS] LSX issues and musing

Noel Chiappa jnc at mercury.lcs.mit.edu
Tue Jul 12 09:47:29 AEST 2022

    > From: Paul Ruizendaal

    > Note that LSX only holds one process in core and swaps other processes
    > (NPROC = 3) out to floppy. It reportedly took several hours for the
    > Terak to self-compile LSX from source.

If one is working in a simulator, and not a real hardware PDP-11, there's a
'trick' one can use to make life a lot easier - for MINI-UNIX, at least; I'll
comment on LSX below.

As I report in the MINI-UNIX Computer History Wiki article: "MINI-UNIX uses
the same file system as V6; this allows MINI-UNIX packs to be 'mounted' on V6
systems (either real, or simulated), which is very convenient for working on
them." So just spin up a V6 in the simulator, mount the LSX/MINI-UNIX pack,
and away you go. The V6 toolchain can be used to compile/link kernels; to
link user commands one will need to import the LSX/MINI-UNIX loader (which,
since V6 is source compatible with LSX/MINI-UNIX, is trivial).

LSX is potentially more complex, as it supports _two different_ file system
formats: the standard V6 one, and a 'contiguous' one which is very similar
to the V6 one (rdwri.c has no conditionals on CONTIG; not so alloc.c,
though), but is not fully compatible. So non-contiguous LSX file systems
can be mounted under V6, but not contiguous ones.


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