Ah, yes, I recall seeing these before. Damned frustrating, those.
The filename that looked like a header made me think it was a case of
headers they weren't needed, since I've gotten BRU tapes output to CD with
extra headers appended before. I had to use a script to fix 'em. But, won't
help with these...
-----Original Message-----
From: Johnny Billquist
Sent: Monday, April 27, 2015 6:51 PM
To: hecnet at Update.UU.SE
Subject: Re: [HECnet] installing LPs on RSX
On 2015-04-28 01:41, Lee Gleason wrote:
> It doesn't take much of a program/script to strip off headers and
> trailers, or add them if required. I've had to do it when service
> bureaus didn't follow my instructions when I've had them read old tapes
> onto files.
>
> What does a dump of the first block look like?
Lee, the tapes are corrupted in a much more sophisticated way.
All tape blocks are there. However, occasionally, they have been reordered.
Assume you have all tape blocks numbered consecutively, including tape
marks, which looks like zero length blocks.
In a corrupted tape, you might then see the blocks in the following order:
1,2,4,5,6,3,7,8,9,...
When a reordering happens, the number of blocks later the "correct"
block appears seems to be anywhere from 1 to 4 blocks ahead. I have not
been able to spot any patterns to when a block reordering have happened,
and I have not been able to spot any pattern to how many blocks later
the reordered block appears.
My only guess is that when Tim Shoppa did the original dumps he used a
program that read multiple blocks in one operation. When a read error
occurred, the program noted, and went back and re-read the bad block.
However, the original read read multiple blocks and the ones following
the read error still got read, and put in the buffer, causing the
reorder to happen. But that is just my guess.
Johnny
>
>
>
> --
> Lee K. Gleason N5ZMR
> Control-G Consultants
> lee.gleason at comcast.net
>
> -----Original Message----- From: Dave McGuire
> Sent: Monday, April 27, 2015 5:22 PM
> To: hecnet at Update.UU.SE
> Subject: Re: [HECnet] installing LPs on RSX
>
> On 04/27/2015 06:04 PM, Johnny Billquist wrote:
>>> Uh-oh...That "HDR1" business looks like part of an ANSI tape label,
>>> not a filename. What do you think?
>>
>> Definitely a corrupted tape.
>
> Yup...After testing several other images from the trailing-edge
> archive, I'm finding the same sort of mess. I knew the BP2 v2.7 image
> was trashed, but it looks like quite a few others are as well. The
> f77_v5_4.tpc one is corrupt too.
>
> What a mess.
>
> Thanks for your help in diagnosing this.
>
> At least some earlier releases are intact, but do you know if any of
> those newer ones have been archived intact anywhere? Do you have them?
>
> -Dave
>
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol