TUHS

tuhs@tuhs.org

6532 discussions

Spell - was tmac: Move macro diagnostics away from

by Doug McIlroy

`quotes' > rules used ... to create British spelling from an American > English database often leave a lot to be desired. Among the BUGS listed for spell(1) in v7 was "Britsh spelling was done by an American". Nevertheless, at least one British expat thanked me for spell -b. He had been using the original "spell", and ignoring its reports of British "misspellings". But, he said, long exposure to American writing had infected his writing. Spell -b was a blessing, for revealed where his usage wobbled between traditions.

7 years, 7 months

Re: [TUHS] Spell - was tmac: Move macro diagnostics away from `quotes\'

by Doug McIlroy

> I am curious if anyone on the list remembers much > about the development of the first spell checkers in Unix? Yes, intimately. They had no relationship to the PDP 10. The first one was a fantastic tour de force by Bob Morris, called "typo". Aside from the file "eign" of the very most common English words, it had no vocabulary. Instead it evaluated the likelihood that any particular word came from a source with the same letter-trigram frequencies as the document as a whole. The words were then printed in increasing order of likelihood. Typos tended to come early in the list. Typo, introduced in v3, was very popular until Steve Johnson wrote "spell", a remarkably short shell script that (efficiciently) looks up a document's words in the wordlist of Webster's Collegiate Dictionary, which we had on line. The only "real" coding he did was to write a simple affix-stripping program to make it possible to look up plurals, past tenses, etc. If memory serves, Steve's program is described in Kernighan and Pike. It appeared in v5. Steve's program was good, but the dictionary isn't an ideal source for real text, which abounds in proper names and terms of art. It also has a lot of rare words that don't pull their weight in a spell checker, and some attractive nuisances, especially obscure short words from Scots, botany, etc, which are more likely to arise in everyday text as typos than by intent. Given the basic success of Steve's program, I undertook to make a more useful spelling list, along with more vigorous affix stripping (and a stop list to avert associated traps, e.g. "presenation" = pre+senate+ion"). That has been described in Bentley's "Programming Pearls" and in http://www.cs.dartmouth.edu/~doug/spell.pdf. Morris's program and mine labored under space constraints, so have some pretty ingenious coding tricks. In fact Morris has a patent on the way he counted frequencies of the 26^3 trigrams in 26^3 byes, even though the counts could exceed 256. I did some heroic (and probabilistic) encoding to squeeze a 30,000 word dictionary into a 64K data space." Doug

7 years, 7 months

Re: [TUHS] Spell - was tmac: Move macro diagnostics away from

by jnc＠mercury.lcs.mit.edu

> From: Will Senn > I see the man page for it in v6, but no executable. The MIT V6+ system had it. They probably took it out of the distro because it was useless without the dictionary, which they didn't have the rights to distribute. Here's the source: http://ana-3.lcs.mit.edu/~jnc/tech/unix/s2/spell.c http://ana-3.lcs.mit.edu/~jnc/tech/unix/s2/spell1.c http://ana-3.lcs.mit.edu/~jnc/tech/unix/s2/spell2.c http://ana-3.lcs.mit.edu/~jnc/tech/unix/s2/spell3.c Noel

7 years, 7 months

TROFF made trivial

by Leah Neukirchen

Hi, I found this paper by bwk referenced in the Unix manpages, in v4 as: TROFF Made Trivial (unpublished), in v5 as: TROFF Made Trivial (internal memorandom), also in the v6 "Unix Reading List", but not anymore in v7. Anyone have a copy or a scan? -- Leah Neukirchen <leah(a)vuxu.org> http://leah.zone

7 years, 7 months

Re: [TUHS] UNIX on S/370

by jnc＠mercury.lcs.mit.edu

> From: Larry McVoy > So tape I can see being more weird, but isn't raw disk just "don't put > it in buffer cache"? One machines/controllers which are capable of it, with raw devices DMA happens directly into the buffers in the process (which obviously has to be resident while the I/O is happening). Noel

7 years, 7 months

DEC Born 60 years ago

by Clem Cole

Cute article from a few days ago in the Telegram about DEC with some since pics that I thought I would pass on to this group. http://www.telegram.com/news/20171118/digital-equipment-born-60-years-ago-i…

7 years, 7 months

Re: [TUHS] Determining what was on a tape back in the day

by jnc＠mercury.lcs.mit.edu

> From: Will Senn > I don't quite no how to investigate this other than to pore through the > pdp11/40 instruction manual. One of these: https://www.ebay.com/itm/Digital-pdp-Programming-Card-8-Pages/142565890514 is useful; it has a list of all the opcodes in numerical order; something none of the CPU manuals have, to my recollection. Usually there are a flock of these "pdp11 Programming Cards" on eBait, but I only see this one at the moment. If you do any amount of work with PDP-11 binary, you'll soon find yourself recognizing the common instructions. E.g. MOV is 01msmr (octal), where 'm' is a mode specifier, and s and r are source and destination register numbers. (That's why PDP-11 people are big on octal; the instructions are easy to read in octal.) More here: http://gunkies.org/wiki/PDP-11_architecture#Operands So 0127xx is a move of an immediate operand. >> You don't need to mount it on DECTape drive - it's just blocks. Mount >> it as an RK05 image, or a magtape, or whatever. > I thought disk (RK05) and tape (magtape) blocks were different... Well, you need to differentiate between DECtape and magtape - very different beasts. DECtape on a PDP-11 _only_ supports 256 word (i.e. 512 byte) blocks, the same as most disks. (Floppies are an exception when it comes to disks - sort of. The hardware supports 128/256 byte sectors, but the usual driver - not in V6 or V7 - invisibly makes them look like 512-byte blocks.) Magtapes are complicated, and I don't remember all the details of how Unix handles them, but the _hardware_ is prepared to write very long 'blocks', and there are also separate 'file marks' which the hardware can write, and notice. But a magtape written in 512-byte blocks, with no file marks, can be treated like a disk; that's what the V6 distribution tapes look like: http://gunkies.org/wiki/Installing_UNIX_Sixth_Edition#Installation_tape_con… and IIRC 'tp' format magtape tapes are written the same way, hardware-wise (so they look just like DECtapes). Noel

7 years, 7 months

Re: [TUHS] Some resources for V6/PDP/SIMH newbs like me

by jnc＠mercury.lcs.mit.edu

> From: Will Senn > (e) UNIX assembler uses the characters $ and "*" where the DEC > assemblers use "#" and "@" respectively. Amusing: the "UNIX Assembler Reference Manual" says: The syntax of the address forms is identical to that in DEC assemblers, except that "*" has been substituted for "@" and "$" for "#"; the UNIX typing conventions make "@" and "#" rather inconvenient. What's amusing is that in almost 40 years, it had never dawned on me that _that_ was why they'd made the @->*, etc change! "Duhhhh" indeed! Interesting side note: the UNIX erase/kill characters are described as being the same as Multics', but since Bell pulled out of the Multics project fairly early, I wonder if they'd used it long enough to get '@' and '#' hardwired into their fingers. So I recently has the thought 'Multics was a follow-on to CTSS, maybe CTSS used the same characters, and that's how they got burned in'. So I looked in the "CTSS Programmer's Guide" (2nd edition), and no, according to it (pg. AC.2.02), the erase and kill characters on CTSS were '"' and '?'. So, so much for that theory! > (l) The names "_edata" and "_end" are loader pseudo variables which > define the size of the data segment, and the data segment plus the bss > segment respectively. That one threw me, too, when I first started looking at the kernel! I don't recall if I found documentation about it, or just worked it out: it is in the UPM, although not in ld(1) like one might expect (at least, not in the V6 UPM; although in V7: http://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/man/man1/ld.1 it is there), but in end(3): http://minnie.tuhs.org/cgi-bin/utree.pl?file=V6/usr/man/man3/end.3 Noel

7 years, 7 months

redirection wildness in v7

by Will Senn

Why does the first of these incantations not present text, but the second does (word is a file)? Neither errors out. $ <word | sed 20q $ <word sed 20q Thanks, Will -- GPG Fingerprint: 68F4 B3BD 1730 555A 4462 7D45 3EAA 5B6D A982 BAAF

7 years, 7 months

Re: [TUHS] UNIX on S/370

by jnc＠mercury.lcs.mit.edu

> From: Clem Cole <clemc(a)ccc.com> > IIRC Tom Lyons started a 370 port at Princeton and finished it at > Amdahl. But I think that was using VM Maybe this is my lack of knowledge of VM showing, but how did having VM help you over running on the bare hardware? Noel

7 years, 7 months

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TUHS