Here's the next iteration of our standard in progress. I've decided to
split the header into two separate ones--a Disk Descriptor Header and a
Track Descriptor Header--as the discussion has been moving us towards.
Desk Descriptor Header
1. Host computer type (2 bytes allowing up to 65536 models to be specified)
2. Hard/soft sector flag (1 byte)
3. Number of tracks (1 byte)
4. Encoding type (1 byte)
5. Disk drive RPM (2 bytes: 1 for whole number, 1 for fraction) [1]
Optional:
6. Archiver Name (24 bytes)
7. Archiver E-mail Address (48 bytes)
8. Archive Description (256-512 bytes)
9. Archive Date (4 bytes: 2 bytes = year, 1 byte = month, 1 byte = day)
A. Archive Time (3 bytes: hour, minute, second)
Maximum size: 598 bytes
[1] If applicable
A Track Descriptor Header will precede each track and give an overall
description of the track:
Track Descriptor Header
1. Track number (2 bytes: 1 for whole number, 1 for fraction) [1]
1. Track format (logical or raw; host computer specific) (1 byte) [2]
2. Track size in bytes (2 bytes) [3]
3. Sector format (single-density, double-density, etc) (1 byte)
4. Sectors in this track (1 byte)
5. Bytes per sector (2 bytes)
6. Bits per byte (1 byte)
7. Offset to next Track Descriptor Header (2 bytes)
Size: 12 bytes
[1] Fraction allows for specifying half- or quarter-track.
[2] If the track is in "raw" format then fields 3-7 are ignored.
[3] The total size in bytes of the raw track image.
As we can see, so far the addition of the headers adds no significant
size to the archive.
Comments?
Sellam International Man of Intrigue and Danger
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Received on Thu Jun 01 2000 - 00:30:49 BST