K
Ken Smith
Guest
In article <etdu1s$8qk_001@s986.apx1.sbo.ma.dialup.rcn.com>,
<jmfbahciv@aol.com> wrote:
your story. It doesn't really matter because even with your new story,
the checksum could have been correct.
[....]
believe at any given instant. You have claimed things in direct
contradiction.
If there was, it could have been changed. Not that it matters because if
we believe your current story, the TAPE.DIR was not created from the
actual tape. Since the TAPE.DIR was created before the tape was written,
there is no need to do an edit write.
BTW: There need not have been an IRG on the tape. A huge number of tapes
have been written without IRGs. Whole companies stayed in business on
reading tapes in one format and converting to another. A big part of
their business was turning unblocked tapes into blocked ones.
--
--
kensmith@rahul.net forging knowledge
<jmfbahciv@aol.com> wrote:
This was based on your claim about what you did. Now you have changedIn article <1173976773.203668.217240@l75g2000hse.googlegroups.com>,
"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote:
On Mar 14, 11:50 am, jmfbah...@aol.com wrote:
In article <1173870480.508596.143...@n76g2000hsh.googlegroups.com>,
"Martin Brown" <|||newspam...@nezumi.demon.co.uk> wrote:
On Mar 13, 10:34 am, jmfbah...@aol.com wrote:
This is the point. It will never be "correct" because the file
contains a checksummed listing of itself.
snip
Do the exercise. Then you will see what I'm talking about.
You really are determined to parade your ignorance. File checksums are
trivial to make internally consistent.
At the simplest conceptual level you could define all files to have
checksum=0 and add some fluff to the end of each one to make it so. In
this case you only need to adjust theTAPE.DIRand since you know the
effect of changing the bytes in the checksum representation on the
checksum it is relatively easy to program a self consistent solution.
then self consistent solutions can be found by SMOP.
It isn't a goal to have the checksum ofTAPE.DIRcorrect. It was
a mandatory goal to have a directory of the tape on the tape. The
tradeoff to accomplish this goal was to have the checksum of
the fileTAPE.DIRnot match the checksum ofTAPE.DIRreported
inTAPE.DIR.
You could so easily have done both if you had just an ounce of
understanding.
It was not possible to edit the tape as Ken would like to have
everyone believe. He has assumed that each file we put on the
tape was tape file; they were not.
your story. It doesn't really matter because even with your new story,
the checksum could have been correct.
[....]
No, the only confusion I've had is which of your stories is the one toNow, I have tried to explain this to him but he doesn't seem to
understand how tapes physically looked.
believe at any given instant. You have claimed things in direct
contradiction.
I have never ever eever said anything that at all implies this.He also seems to
assume that tapes were directory media but the are not; they
are unit record media.
Was there an IRG?He keeps assuming that the TAPE.DIR
was one, and only one, record. It was not. It was also not
separated from the other files put on the tape by the
magtape equivalent of an EOF.
If there was, it could have been changed. Not that it matters because if
we believe your current story, the TAPE.DIR was not created from the
actual tape. Since the TAPE.DIR was created before the tape was written,
there is no need to do an edit write.
BTW: There need not have been an IRG on the tape. A huge number of tapes
have been written without IRGs. Whole companies stayed in business on
reading tapes in one format and converting to another. A big part of
their business was turning unblocked tapes into blocked ones.
--
--
kensmith@rahul.net forging knowledge