Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!elroy.jpl.nasa.gov!decwrl!pa.dec.com!nntpd.lkg.dec.com!star.enet.dec.com!parke From: parke@star.enet.dec.com (Bill Parke) Newsgroups: comp.misc Subject: Re: How many different ASCII textfile formats are there? Message-ID: <23015@shlump.lkg.dec.com> Date: 30 May 91 16:10:57 GMT References: <1991May27.162515.665@looking.on.ca> <1991May29.174634.23343@csl.dl.nec.com> Sender: newsdaemon@shlump.lkg.dec.com Reply-To: parke@star.enet.dec.com (Bill Parke) Organization: Digital Equipment Corporation, Nashua NH Lines: 47 In article <1991May29.174634.23343@csl.dl.nec.com>, harrison@csl.dl.nec.com (Mark Harrison) writes: > >The DEC-20 was a 36-bit machine that encoded text files something >like this: If the high bit was set, the other bits were the line >number. Otherwise there were 5 seven-bit characters stuffed in >the word. The DEC-10 and 20 7 bit ASCII was stored form the top (bit 0) of the word to the bottom. This leat the bottom bit unused and by convention it became the "line number" bit. This led to all sorts of amusing incidents such as my progam which worked correctly but was almost the death of a TA in my FORTRAN class. It included the statement "WRITE I=6". Hint, it correctly assigned 6 to I and yealded no compile errors. > >There was also a representation where there were 6 six-bit characters >in one word. This was used in the linker, etc, but it could have >been used for text files. I think that character set was called >SIXBIT. Sixbit was used for may symbol table and file name representations. There was also a form known as RAD50 which represented the symbol name subset of the alphabet and left 4 bits to encode data about the name for the linker. This was the linkers internal form. Sixbit file names could be made amusing with PIP under TOPS-10 by explicitly building the octal. (Teners might recognize #001216120000.#000000 ) D**n, these wimpy machines with a fixed byte size. > >The above is rather vague in my mind, and probably not entirely >accurate. :-) >-- >Mark Harrison | Note: harrison@ssd.dl.nec.com and >harrison@csl.dl.nec.com | necssd!harrison are not operating at >(214)518-5050 | present. Please forward mail through the > | above address. Sorry for the inconvenience. > -- Bill Parke VMS Development decwrl!star.enet.dec.com!parke Digital Equipment Corp parke@star.enet.dec.com 110 Spit Brook Road ZK01-1/F22, Nashua NH 03063 The views expressed are my own.