22 Oct
2004
22 Oct
'04
10:10 p.m.
At 11:12 PM 10/22/2004, Graham wrote:
I think RT-11 had version numbers (in the style of
VMS), but GUTS
showed only the top-level file, and had a "pop" command which deleted
the most recent file and made the version below it visible.
The source is lost (though we do have a disk pack which *may* contain
the OS, if it is still readable) but a scan of the three-book report
is available online: http://history.dcs.ed.ac.uk/archive/scans/guts/ -
Orange is the users guide; Red - system design; Yellow - selected
source listings.
Another PDP/11 O/S was "MUSS". There's a manual page for it
here:
http://history.dcs.ed.ac.uk/archive/os/emas/users/ercm09/emas-2900/docum_mm…
I think the sources of MUSS along with the FEP's and ERTE are in
that directory somewhere too. DEIMOS, MUSS, ERTE and the FEPs
were written by Brian Gilmore, now head of the Computing Service.
Ian Young wrote an operating system for the PDP-11 called "rats"
as a student project - I believe he has a paper listing which we
might have scanned some day. That was the first implementation
of lightweight threads that I remember seeing.
All the Edinburgh software was written in Imp, except for a few
assembler parts, but we had our own assembler for it as well:
http://history.dcs.ed.ac.uk/archive/os/emas/users/ercm09/emas-2900/asst11j.…
There were two compilers for the system; one written by the ERCC
based on a simpler bootstrapping compiler called "SKIMP" -
Though my wife likes RT11,
I think she would draw the line at a MUSS of Red, Orange and Yellow lmp
rats GUTS.
RT11 file structure didn't have version numbers.
Didn't even keep time of creation, just a single date.
No attributes either, except RO in later versions.
Just 1 directory for entire disk.
There were a few words available in each directory file entry for user
applications.
Big thing: files had to be contiguous.
As files were deleted they made free spaces.
New files could only be as large as the largest free space on a disk.
Had to compress (squeeze) the file structure periodically to consolidate
all the free spaces.
My wife, before we were married, used that to set the hook in me.
She was a Dibol programmer who had graduated from programming on a PDP 8/A
to a PDP 11/34.
I was the geek upstairs building M6800 tape readers and programming them
with the ASR33.
No command language in those days, RT11 V2c was strictly command line.
Dibol compiler had a /S switch to suppress data division summary in source
listing.
PIP /S was used to squeeze the disk.
Dibol would let you use ^C to stop the program and source listing.
That was accepted practice.
PIP would let you use ^C to abort it in the middle of rewriting your disk
directory.
That was definitely NOT good practice.
Girl comes crying into room, "I did PIP/S and not DICOMP/S and ^C'd and
I've lost all my work!!!".
(Don't you just love it when they talk like that!)
Geek boy helps pretty programmer recover data, gets big kiss, etc. etc.
Yup, RT11 was definitely useful despite it's limitations.
I doubt she'd have hung around long enough for us to meet if she'd had to
work on a MUSS of lmp rats GUTS.
:-)
Ed K.