[sebhc] Re-creating actual floppies from archive

Dwight Elvey dwight.elvey at amd.com
Tue Mar 14 20:23:49 CST 2006

>From: "Barry Watzman" <Watzman at neo.rr.com>
>Interleave matters only when formatting a disk; it does not matter when
>reading or writing.  The sector number is indeed recorded on the disk of a
>soft-sector disk, but it's in a "header", not the data (so if the format is
>9 sectors of 256 bytes per sector, you really have a full 9*256 of data).
>[Also, for what it's worth, the software only looks for a match between the
>sector # in the header and the requested sector.  You can have gaps, or odd
>sector numbers (sector 237 appearing in a 9-sector track) and that's fine as
>long as everything is understood by everyone using the diskette].
>Note that while early disk controllers could benefit from this, even with a
>2MHz 8080, an 8" controller using a 1771 chip (the very first Western
>Digital Chip, single density only) could read at full speed with zero

 Even if the chip can read at full speed, the application software
might be asking for only a sector at a time. This was true of
the BASIC that was on the H89. I had a friend with an accounting
program. It was real slow until I interleaved his sectors for him.
It ran about 7 or 8 times faster.


Delivered by the SEBHC Mailing List

More information about the Sebhc mailing list