User`s guide

DUMP
• If you are dumping a file, the block numbers you specify are relative to the
beginning of that file. If you are dumping a device, the block numbers are the
absolute (physical) block numbers on that device.
Magtapes
RT–11 handles operations involving magtape differently from operations involving
random-access devices. If you dump an RT–11 file-structured tape and specify only
a device name in the file specification, RT–11 reads only as far as the logical end-
of-tape. Logical end-of-tape is indicated by an end-of-file label (EOF1) followed by
two tape marks. For nonfile-structured tape, logical end-of-tape is indicated by two
consecutive tape marks.
If you dump a cassette and specify only the device name in the file specification, the
results are unpredictable. For magtape dumps, tape-mark messages appear in the
output listing as RT–11 encounters them on the tape.
HOW TO INTERPRET A DUMP LISTING
To understand how DUMP translates binary code, look at the following one-sentence
contents of the file FOX.TXT:
THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG.
The next two example file listings are the first 64 bytes of two different dumps of the
preceding file. The 448 bytes of the two dump listings that are not shown list zeros
in the rest of the 512 bytes of each file to show that they contain no information—the
smallest unit of information RT–11 deals with on a disk is 1 block (512 bytes). When
you create a file with KED/KEX, the editor allocates a minimum of 1 block for your
file, even if it contains only a few bytes of information.
The first listing is the default listing, without options.
• The first line of the listing contains the input-file specification.
• The second line specifies the input-file block number at which the listing starts.
• The left column of numbers with slashes is the octal byte offset from the
beginning of the block. Each row across represents 16 bytes or 8 words of binary
information; the 17th
10
byte is at offset 20, the 33rd byte is at offset 40 and so
forth.
• The eight columns following the byte offsets contain eight words in octal code.
• The ASCII equivalent of the eight words is displayed in the column to the right
of the octal words.
First Listing
FOX.TXT
BLOCK NUMBER 000000
000/ 044124 020105 052521 041511 020113 051102 053517 020116 *THE QUICK BROWN *
020/ 047506 020130 052512 050115 042105 047440 042526 020122 *FOX JUMPED OVER *
040/ 044124 020105 040514 054532 042040 043517 000056 000000 *THE LAZY DOG....*
060/ 000000 000000 000000 000000 000000 000000 000000 000000 *................*
RT–11 Command Descriptions 99