Adding Jim Willing's input to the fray:
1. Host computer type (2 bytes allowing up to 65536 models to be
specified)
2. Hard/soft sector flag
3. Number of tracks
4. Track format (host computer specific)
5. Sector format (single-density, double-density, etc)
5. Sector data format - this will specify what format the archived sector
is in (raw data? logical bytes?)
6. Sectors per track
7. Bytes per sector
8. Bits per byte
I think the measure of usefulness of this standard will be if it can
easily define the format of a standard disk from most any platform as well
as being able to handle different exceptions.
What I mean is, can one take a regularly formatted diskette from any
computer that has T number of tracks and S number of sectors per track and
B number of bytes per sector and describe it with the same header as a
disk with some totally hardware specific formatting?
The Archive Description Header should be able to easily describe standard
disk formats so as to be easily implementable across multiple platforms,
while also being powerful enough to describe exotic platform
specific formats that would allow reconstruction of an original disk back
to the original platform.
The reading and writing of the disks will obviously have to be done with
applications running on the actual hardware, that will be able to analyze
the format of the disk and pass information about any special formatting
to the machine where the archive is to be processed and stored.
We are NOT creating a description for hardware that can read any disk
format ever put out. That is wholly unfeasible. We are creating a
software standard that will allow the contents of a diskette to be
universally defined in a manner that allows complete reconstruction of a
diskette on the original platform.
So for disks that cannot be read by PC hardware (which is what I currently
consider to be "universal") utilities will have to be created on the
original platform to both read and write the diskette. The best example
would be the Apple ][. A utility will have to be written for the Apple ][
that can read the raw disk data, analyze the contents, and return the
sector (or track) data back to the "universal" host over a serial port
along with a description of how that data was formatted on the disk. That
description will then get encoded into the Archive Description Header.
Which leads me to this thought: is preserving the actual format of the
disk even necessary for posterity? Is the goal here to be able to make
exact copies of the disk to be able to run on the hardware well into the
future? Or is the actual data itself more important?
This is getting too complicated, but what I mean is, instead of trying to
archive an oddball format from, say, the Apple ][ that was designed to
thwart copying of the disk and making archiving it a challenge, would it
be better to just take the software contained on that disk and convert it
to a standard format that can be more easily archived?
Is there historical value to preserving the original format? I think so.
Sellam International Man of Intrigue and Danger
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Received on Tue May 30 2000 - 10:31:50 BST