Good information, but this thread is about DECtape, not 9-Track magtapes...
The format looks about right for 9-track DOS-11 magtapes; I remember writing code to extract files from them on the -10.
It's not right (or at least, not complete) for the block-addressable DECtapes.
I don't think DOS-11 would have been documented in any of the references cited.
There's now a SIMH repo on github; your utility could go into the tools section.
This communication may not represent my employer's views, if any, on the matters discussed. On 28-Mar-13 14:09, Larry Baker wrote:
On 28 Mar 2013, at 5:24 AM, <[email protected] <mailto:[email protected]>> <[email protected] <mailto:[email protected]>> wrote:Google 'AA-JS16A-TC' for some Files-11 format information; I'd have to think a bit on the DOS-11 format.RSX/VMS Files-11 tapes are ANSI labeled tapes. I know OpenVMS also used HDR3/4 labels for RMS information. There was a MOUNT option to suppress writing those labels.I wrote an RSX/VMS program that will scan an unknown tape and decode it for you. (If anyone wants it, let me know where I should upload it.) The DOS format decoder looks for a 14 byte (physical) record at the start of the file. It is decoded by the following code:C C... DEC DOS labels C Call R50ASC ( 6, buffer( 1), ascbuf( 1) ) Call R50ASC ( 3, buffer(13), ascbuf( 7) ) ascbuf(10) = '.' Call R50ASC ( 3, buffer( 5), ascbuf(11) ) ltemp(1) = buffer(7) ltemp(2) = 0 mem = itemp ltemp(1) = buffer(8) grp = itemp ltemp(1) = buffer(11) ltemp(2) = buffer(12) jday = MOD(itemp,1000) year = itemp/1000 + 70 Call JDCONV ( jday, mon, day, year ) ltemp(1) = buffer( 9) ltemp(2) = buffer(10) Write (STDOUT,619) ifile, grp, mem, ascbuf, day, month(mon), 1 year, itemp 619 Format (//' File ', I4, ':', T34, '"', '[', O3.3, ',', O3.3, ']', 1 13A1, 2X, I2, '-', A, '-', I2.2, ' <', O3.3, '>', '"') The DOS label contents are:Words 1-2 RAD50 characters 1-6 of the file name part (before the implied period)Word 3 RAD50 characters 1-3 of the file type (after the implied period)Word 4 Octal File owner's User Identification Code (group code in high-order byte, member code in low-order byte)Word 5 Binary File creation date ( 1000 * ( year - 1970 ) + Julian day )Word 6 Octal File protection (low-order to high-order RWED bits: read, write, extend, delete; grouped low-order to high-order for system, owner, group, world) Word 7 RAD50 characters 7-9 of the file name part (before the implied period)The references I used to write the program (back in the 1980's) are below. Which reference had the DOS label format I don't remember (if any of them did).6 References [1] American National Standards Institute, 1978, Magnetic Tape Labels and File Structure for Information Interchange (ANSI X3.27-1978). [2] Digital Equipment Corp., 1985, RSX-11M/M-Plus MCR Operations Manual (Order no. AA-FD10A-TC). [3] Digital Equipment Corp., 1985, RSX-11M-Plus Command Language Manual (Order no. AA-FD04A-TC). [4] Digital Equipment Corp., 1985, RSX-11M/M-Plus and Micro/RSX I/O Operations Reference Manual (Order no. AA-FD14A-TC). [5] Digital Equipment Corp., 1985, RSX-11M/M-Plus I/O Drivers Reference Manual (Order no. AA-FD09A-TC). [6] Digital Equipment Corp., 1984, VAX/VMS Command Definition Utility Reference Manual (Order no. AA-Z408A-TE). [7] Digital Equipment Corp., 1986, VAX/VMS DCL Dictionary (Order no. AA-Z200C-TE). [8] Digital Equipment Corp., 1984, VAX/VMS Mount Utility Reference Manual (Order no. AA-Z424C-TE). [9] Digital Equipment Corp., 1986, Guide to VAX/VMS Disk and Magnetic Tape Operations (Order no. AI-Y506B-TE). [10] Digital Equipment Corp., 1986, VAX/VMS I/O User's Reference Manual: Part I (Order no. AA-Z600C-TE). [11] International Business Machines Corp., 1978, OS/VS Tape Labels (Order No. GC26-3795-1). Larry Baker US Geological Survey 650-329-5608 [email protected] <mailto:[email protected]> _______________________________________________ Simh mailing list [email protected] http://mailman.trailing-edge.com/mailman/listinfo/simh
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