32 sector 8" floppies

From: CLASSICCMP_at_trailing-edge.com <(CLASSICCMP_at_trailing-edge.com)>
Date: Fri Jul 30 10:16:51 1999

>> It would be well to remember that, back when hard-sectoring was common, it
>> was considered more efficient than soft-sectoring. Shugart 801 drives were
>> certainly available with hard-sector support as an option. Hard-sectoring
>> did cost more, hence died off quickly enough.

>Why was hard-sectoring considered more efficient? IIRC, the soft sectored
>disks had more capacity than a comparable hard-sectored disk.

It depends on what you're comparing *with*. 32-sectored hard-sectored
8" floppies have a bit more capacity than IBM 3740 (26-sector) soft-sector
format. But once you start going to double density, longer (and
fewer) sectors, etc., the soft-sector formats start looking better,
but only because the hard-sectored disks weren't evolving anymore at that
point. They could've kept up, if it wasn't for advances in floppy
disk controller technology which made the soft-sectored formats more

In terms of early (early and mid-70's) hardware, hard-sectored floppies
required less "smarts" in the disk controller because they don't have to deal
with sector marks in the read signal. (Remember that early 8" soft-sectored
floppy controllers lacked the smarts to write the address marks, and
they reserved that function for special-purpose formatters. We aren't
talking about a LSI chip, we're talking about a square foot or two
of PCB stuffed densely with SSI TTL.) But
then the FDC-on-a-chip came along (from WD, NEC, and others) and these
had built-in circuitry for dealing with soft-sectored details. Others
(like Wozniak) moved the FDC functions to the CPU and avoided both
the FDC-on-a-chip *and* the square feet of PCB's typical of previous
floppy disk controllers.

 Tim Shoppa                        Email: shoppa_at_trailing-edge.com
 Trailing Edge Technology          WWW:   http://www.trailing-edge.com/
 7328 Bradley Blvd		   Voice: 301-767-5917
 Bethesda, MD, USA 20817           Fax:   301-767-5927
Received on Fri Jul 30 1999 - 10:16:51 BST

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