[TUHS] A re-analysis of some DECtapes from dmr

All, I received this detailed e-mail from Yufeng Gao who has done a great job at analysing some of the DECtapes that Dennis made available to the Unix Archive. I'm sure many of you would be interested and, possibly, could provide some feedback on his work. A tarball of his efforts are here: https://mega.nz/file/1cJFTJxT#BgszYuFc_ebSMaQXAIG5b2NtaGInPWMoaxExPM5Lr9Y Cheers, Warren P.S. I have a follow-up e-mail coming ... ----- Forwarded message from Yufeng Gao ----- Subject: UNIX DECtapes from Ritchie Hi Warren, I am writing you this email after seeing the DECtapes from Dennis Ritchie that you put up last year. I found them while playing around with the early C compilers on Ritchie's site. After some research into the tapes, I have written a parser to parse them and convert them into tarballs suitable for preservation. Most importantly, the 'dmr' tape and 's1' tape are currently not decoded properly. The biggest issue with the current decoding of the 's1' tape is, well, there is none. After quickly glancing over the tape, I have concluded that it is in fact not one of the middle tapes of an rkd(1) backup, but a copy of UNIX INIT DECtape from a version of UNIX between V1 and V2. I have extracted its contents: Mode UID GID Size Date Name ---------- --- --- ----- ------------------- ------------ -rw-rw-rw- 0 0 512 1970-01-01 00:00:00 [vcboot] -rw-rw-rw- 0 0 2048 1970-01-01 00:00:00 [bos] -rw-rw-rw- 0 0 12288 1970-01-01 00:00:00 [wunix] -rw-rw-rw- 0 0 12288 1970-01-01 00:00:00 [cunix] -rw-rw-rw- 0 0 3072 1970-01-01 00:00:00 [unassigned] -rwxr-xr-x 1 0 424 1970-01-01 00:00:00 /etc/init -rwxrwxrwx 3 0 446 1970-01-01 00:00:00 /etc/getty -rwxr-xr-x 3 0 82 1970-01-01 00:00:00 /bin/chmod -rwsr-xr-x 0 0 794 1970-01-01 00:00:00 /bin/date -rwsr-xr-x 0 0 1290 1970-01-01 00:00:00 /bin/login -rwsr-xr-x 0 0 232 1970-01-01 00:00:00 /bin/mkdir -rwxr-xr-x 1 0 954 1970-01-01 00:00:00 /bin/sh -rwsr-xr-x 0 0 3678 1970-01-01 00:00:00 /bin/tap -rwxr-xr-x 3 0 2010 1970-01-01 00:00:00 /bin/ls 578 blocks, 98 (16.96%) used, 480 (83.04%) free. B = boot; D = directroy; . = free; X = file data; O = bos; W = wunix; C = cunix; S = rf slack; U = unassigned program; |0123456789ABCDEF --+---------------- 00|BOOOOWWWWWWWWWWW 01|WWWWWWWWWWWWWCCC 02|CCCCCCCCCCCCCCCC 03|CCCCCUUUUUUSSSSS 04|SDXDXDXDXXDXXXDX 05|DXXDXXXXXXXXDXXX 06|XD.............. 07|................ <...> What is significant here is it contains the vcboot and bos programs mentioned in bproc(7), as well as a Warm and a Cold UNIX kernel. This version of UNIX appears to be between V1 and V2, which I believe is the earliest to exist in binary form. The reason why I say it's between V1 and V2 is its bos program accepts the following console switches compared to V1 and V2: | UNIX V1 | s1 | UNIX V2 ----------------------+----------+-------+--------- Warm boot | [1]73700 | ??? | ??? Cold boot | 1 | 1 | 1 Unassigned 3K prog | 2 | 2 | Dump core & halt | 10 | 10 | 10 Boot from RK | | 20 | 20 Dump core & warm boot | | 40 | 40 Boot from paper tape | 0 | 0 | 0 Load DEC loaders | 57500 | 57500 | 77500 ----------------------+----------+-------+--------- UNIX load address | 400 | 400 | 600 ----------------------+----------+-------+--------- The boot-from-unassigned-3K-program option was probably in the process of being depreciated, as the 3K of space is also loaded as a part of the Cold UNIX despite it not being used by the Cold UNIX kernel. The list of files on the 's1' tape also appear to be between V1 and V2: | V1 | s1 | V2 -----------+-----+-----+----- /etc/init | Yes | Yes | Yes /etc/getty | No | Yes | Y/N /bin/chmod | Yes | Yes | Yes /bin/chown | Yes | No | No /bin/date | No | Yes | Yes /bin/login | No | Yes | Yes /bin/cp | Yes | No | No /bin/ln | Yes | No | No /bin/ls | Yes | Yes | Yes /bin/mkdir | Yes | Yes | Yes /bin/mv | Yes | No | No /bin/rm | Yes | No | No /bin/rmdir | Yes | No | No /etc/mount | No | No | Yes /bin/sh | Yes | Yes | Yes /bin/stat | Yes | No | No /bin/tap | Yes | Yes | Yes -----------+-----+-----+----- Given that the files on this tape are identical to the same files on the 's2' tape and that the files on the 's2' tape are also sort of between V1 and V2, and that this tape is named 's1' while the other is named 's2', they are probably from the same version of UNIX. I have tried booting the 's1' tape using SIMH, but unfortunately it did not work and I have not yet attempted to debug it. Next I'm going to talk about the 'dmr' tape. It’s interesting, most of it was written by tap(1) running under UNIX V1-V2, but files in the ./paper directory were written by tap(1) running under UNIX V4. When decoded using the tap(1) program itself, the timestamps and access modes of those files are garbled. My program corrected the timestamps and access modes in the converted tar(1) archive. The same goes for the 'nsys' tape. The tar(1) conversion of 's2' (/Archive/Distributions/Research/1972_stuff/s2-bits.tar.gz) in the TUHS archives is missing some files in the /etc directory - compare it with mine and Ritchie's (Ritchie's has wrong timestamps and access modes, however). Speaking of timestamps and the 's2' tape, the timestamps outputted by tap(1) are inaccurate because 1972 is a leap year and the ctime(3) function hard coded 28 for the number of days in February. I have attached an archive of my tar(1) conversion of each tape, as well as tarballs containing all the slack space data and unused blocks which I dumped for data recovery and forensic analysis purposes. There are some interesting bits and pieces in the unused blocks of various tapes, but I have not had time to look into them in detail. Just a very quick summary: * The 'config' tape has leftover of a dictionary file. * The 'dmr' tape has some assembler manual ?roff leftover. * The 'dmr2' tape has some paper ?roff leftover. * The 'e-pi' tape has a lot of interesting binary stuff, including bits and pieces of a B compiler from what I can tell. * The 'ken' tape has some C source fragments and Thompson’s mail templates and some UNIX manual ?roff leftover. * The 'ken-du' tape has some paper ?roff leftover. * The 'ken-sky' tape has some binary leftover. * The 'nsys' tape has some source code leftover of what seems to be the kernel. * The 's1' tape has some source code leftover of what seems to be userland programs. * The 'scratch' tape has some binary and source listing and ?roff leftover. * The 'unix' tape has some binary leftover. I hope that these newly extracted stuff could be put up in the TUHS archives :). If the attachment in this email somehow doesn't come through, I have also uploaded the archive [1]here. I have a disassembly of vcboot and bos from 's1', they may help with the UNIX V1 reconstruction project - let me know if you need them. If you can get the 's1' kernel to boot, I'd like to also receive an update. Sincerely, Yufeng Gao ----- End forwarded message -----