21 Sep
2023
21 Sep
'23
5:34 a.m.
On 9/20/23 20:33, Dennis Boone via cctalk wrote:
Looks like there might be some grist for my mill. I'll have to take
some time staring at hex dumps, but maybe I'm very close.
1600 bpi tape. What's interesting is that all of the tape blocks are
what one would consider to be odd sizes: 87 bytes, 4101 bytes, etc.
The distance between the CMS header and the CMSN header appears to be
much larger than 800 bytes--the first, for example is about 4K . The
next CMS file name header follows about 80 bytes later.
I don't see any indication of file or record lengths in the header,
which is troubling. The first block has the following (ASCII version)
Ive got a tape
here from what I believe to be a VM system. The
structure is unknown to me, although I can possibly take a stab at
it. Lots of data between tapemarks that seems to consist of a number
of records that start out something like this (translated from
EBCIDC):
I think this might be the older VMFPLC (not VMFPLC2) format, used by IBM
for software distribution and other things. The format seems fairly
simple: Five character block header (x'02' 'CMS' 'N' or
'0'), 800 bytes
of contents. First block is the FST for the file.
https://www.garlic.com/~lynn/2003b.html#42
Old VMFPLC may be just CMS TAPE DUMP under the covers.
De 00000000 02 43 4d 53 46 44 41 54 41 20 5f 4e 55 4c
4c 5f |.CMSFDATA _NULL_|
00000010 3b 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |; |
00000020 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
*
000000a0 20 20 20 20 20 20 20 20 20 46 49 4c 45 20 20 20 | FILE |
000000b0 20 20 20 50 52 49 4e 54 3b 20 20 20 20 20 20 20 | PRINT; |
000000c0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
*
000000f0 20 20 20 20 20 20 20 20 20 54 49 54 4c 45 20 20 | TITLE |
00000100 20 20 27 3d 3d 3d 3d 3d 3d 3e 20 42 41 44 2c 20 | '======> BAD, |
00000110 4d 49 53 53 49 4e 47 20 4f 52 20 45 58 54 52 41 |MISSING OR EXTRA|
00000120 20 43 41 52 44 20 23 27 27 53 20 3c 3d 3d 3d 3d | CARD #''S
<====|
00000130 3d 3d 27 3b 20 20 20 20 20 20 20 20 20 20 20 20 |=='; |
In any case, I'll dig a bit. This is a lone tape out of a set, so no
comparatives.
All the best,
Chuck
--Chuck