On Fri, 26 May 2000, John Foust wrote:
> Below is the section from the manual that describes their
> file format.
>
<...>
>
> Each sector written to the file is optionally preceded by an
> 8-byte header record of the following form:
>
>
> +------+------+------+------+------+------+----------+
> | ACYL | ASID | LCYL | LSID | LSEC | LLEN | COUNT |
> +------+------+------+------+------+------+----------+
>
> ACYL Actual cylinder, 1 byte
> ASID Actual side, 1 byte
> LCYL Logical cylinder; cylinder as read, 1 byte
> LSID Logical side; or side as read, 1 byte
> LSEC Sector number as read, 1 byte
> LLEN Length code as read, 1 byte
> COUNT Byte count of data to follow, 2 bytes. If zero,
> no data is contained in this sector.
>
> All sectors occurring on a side will be grouped together;
> however, they will appear in the same order as they occurred on
> the diskette. Therefore, if an 8 sector-per-track diskette were
> scanned which had a physical interleave of 2:1, the sectors might
> appear in the order 1,5,2,6,3,7,4,8 in the DOS dump file.
>
> After the last specified cylinder has been written to the DOS
> file, AnaDisk returns to the Main Menu.
This is a good start. The header should include a byte that contains a
flag indicating the status of the sector (good, bad, etc).
What about odd formats? I take my experience from the Apple ][. You had
stuff like half-tracks and quarter-tracks (the head was stepped half-way
or half of half-way between tracks to store data), odd disk formats
(custom sector sizes, custom sector layouts, etc.), synchronization
between tracks (one copy protection scheme was to write a two tracks so
that if a seek was done from one track to the other, a specific sector
would be expected under the head as soon as it got to the next track).
Many of these methods were also used on the C64, and I believe on the
Atari 8-bits.
Software has been written on the Apple ][ to read the raw track data and
dump it into a file that could then be compressed and sent over a modem
line. Copy protected disks could only be archived in this manner, or else
they would need to be cracked.
I have a ton of original software for the Apple ][, and a ton of cracked
software. I'd like to archive both, as the cracked copies often included
the "credits" that the cracker placed on the software for having cracked
it, and this is part of the culture (in fact it's a fairly interesting
part of the culture that I'd like to document some day).
The AnaDisk software doesn't seem to accomodate copy protected or
custom-format disks. The standard will have to address these disks as
well.
Sellam International Man of Intrigue and Danger
-------------------------------------------------------------------------------
Looking for a six in a pile of nines...
Coming soon: VCF 4.0!
VCF East: Planning in Progress
See
http://www.vintage.org for details!
Received on Fri May 26 2000 - 20:44:37 BST