[sebhc] h17 and h8d disk images
melamy at earthlink.net
Wed Sep 1 19:25:32 CDT 2004
make that three ways because I have had cp/m systems that interleaved the
sector on the disk on the physical media.
The floppy controller could care less when the track is formatted as to
which sector was which on a soft sector disk.
best regards, Steve Thatcher
At 07:45 PM 09/01/2004 -0400, Barry Watzman wrote:
>There are two ways to interleave.
>In the 1st method, used by CP/M, you have an interleave table in the
>operating system itself. The sectors are in physical order on the diskette,
>but are not used in physical sequence. That is, CP/M (on an 8" disk) uses
>sector 1 then 7 then 13, then 19, etc.
>The other way is to have the OS use the sectors sequentially (1,2,3 etc.)
>but to do the interleaving when the disk is formatted. So the OS will ask
>for sector 1, 2, 3 ...., but on the disk the sector after sector 1 is not 2
>but rather something else. There is no requirement that the sectors on the
>disk be in sequential order. In fact, there is no requirement that they be
>contiguous, or that they be "positive" numbers (if one wants to interpret
>them as signed numbers). They are more like labels than actual numbers,
>they can be in any sequence, and there can be gaps (a fact on which may copy
>protection schemes rely).
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