source code for PDP-7 dsw command

Sorry for the repetition if you've already seen this. The source code for the PDP-7 Unix dsw command was just reposted in alt.sysadmin.recovery. Here's the article: Newsgroups: alt.sysadmin.recovery From: flaps(a)dgp.toronto.edu (Alan J Rosenthal) Subject: Re: Time to train not one, but 15 PFY's. . . Date: 23 Nov 99 22:17:39 GMT SKaranyi+n0(a)localhost.ruhr.de (Wolfgang Schelongowski) writes: ... Fascinating. It appears that although it was claimed to stand for "delete from switches", and this is what it actually did, it was also a pun on the amateur radio abbreviation. The later program described in the previous article seems to be named after the original (and no longer deserves the name "dsw"). And the original "dsw" was *not* interactive. The original "dsw" program uses the console switches to specify the file to be deleted, for file names with funny characters in them. It was astonishingly round-about: you would set the number 'n' on the switches, then run dsw, and it found the name of file #n in the current directory, and then created a core dump which when executed, would delete that file. Sheesh. It's not like there wasn't an unlink() system call; why not just unlink it? Well, I guess the idea is that you would examine the core file and make sure it was deleting the right file. But there are still obvious trivial improvements. And why not take the number in argv[1]? Of course this was well before it was possible to write something like "rm `command`". It is interesting that the 1971(?) man page mentions that really there should be an option to rm, and then goes on to specify "rm -i *" behaviour as appropriate for a serious version of this command. That "BUGS" section sure was a good idea. I still can't believe the sysV people renamed it to "NOTES". dmr posted the man page of the original dsw program to net.general in 1981, and it can thus be found at http://communication.ucsd.edu/A-News/NET.general/81.08.12_research.19_net.g… (there is an earlier posting about dsw, which is a joke) dmr also posted the source code to net.unix-wizards in 1984. This is too late for the "oldnews" archive, so I'll include the article here. I love his comment that he considered posting instead to net.sources. Date: 8 Dec 84 09:45:09 GMT From: dmr(a)research.UUCP Newsgroups: net.unix-wizards Subject: dsw: pdp7 memorabilia I happened to dredge up an old notebook and found a listing of the PDP-7 version of dsw. Because several people have approached me recently about reviving a version of PDP-7 Unix as a sort of paleontological exhibit, and because the subject has been discussed here, I thought people might be interested in seeing the code. I first considered net.sources, but decided not to carry whimsy too far. Dennis Ritchie Notes: 1) The assembler has Knuth-style temporary labels but no literals. 2) The name of the current directory was evidently ".." 3) Formatting is faithfully reproduced. 4) "sys save" makes a core image. ------ " dsw lac djmp dac .-1 oas cla cma tad d1 dac t1 sys open; dd; 0 1: lac d2 sys read; dir; 8 sna sys exit lac dir sna jmp 1b isz t1 jmp 1b wr: lac d1 sys write; dir+1; 4 lac d1 sys write; o12; 1 sys save do: sys unlink; dir+1 sys exit d1: 1 d2: 2 o12: 012 t1: 0 djmp: jmp do dd: 056056; 040040; 040040; 040040 dir: .=.+8 Received: (from major@localhost) by minnie.cs.adfa.edu.au (8.9.3/8.9.3) id LAA06682 for pups-liszt; Wed, 24 Nov 1999 11:13:19 +1100 (EST)